Lincoln Electric Soldering Gun DC 655 User Manual

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SVM142-A  
September, 2002  
IDEALARC DC-655  
For use with machine code number 10501 thru 10510  
Safety Depends on You  
Lincoln arc welding and cutting  
equipment is designed and built  
with safety in mind. However,  
your overall safety can be  
increased by proper installation  
. . . and thoughtful operation on  
your part. DO NOT INSTALL,  
OPERATE OR REPAIR THIS  
EQUIPMENT WITHOUT READ-  
ING THIS MANUAL AND THE  
SAFETY PRECAUTIONS CON-  
TAINED THROUGHOUT. And,  
most importantly, think before  
you act and be careful.  
SERVICE MANUAL  
Copyright © 2002 Lincoln Global Inc.  
• World's Leader in Welding and Cutting Products •  
• Sales and Service through Subsidiaries and Distributors Worldwide •  
Cleveland, Ohio 44117-1199 U.S.A. TEL: 216.481.8100 FAX: 216.486.1751 WEB SITE: www.lincolnelectric.com  
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ii  
ii  
SAFETY  
ARC RAYS can burn.  
ELECTRIC SHOCK can kill.  
3.a. The electrode and work (or ground) circuits  
are electrically “hot” when the welder is on.  
Do not touch these “hot” parts with your bare  
skin or wet clothing. Wear dry, hole-free  
gloves to insulate hands.  
4.a. Use a shield with the proper filter and cover  
plates to protect your eyes from sparks and  
the rays of the arc when welding or observing  
open arc welding. Headshield and filter lens  
should conform to ANSI Z87. I standards.  
4.b. Use suitable clothing made from durable flame-resistant  
material to protect your skin and that of your helpers from  
the arc rays.  
3.b. Insulate yourself from work and ground using dry insulation.  
Make certain the insulation is large enough to cover your full  
area of physical contact with work and ground.  
4.c. Protect other nearby personnel with suitable, non-flammable  
screening and/or warn them not to watch the arc nor expose  
themselves to the arc rays or to hot spatter or metal.  
In addition to the normal safety precautions, if welding  
must be performed under electrically hazardous  
conditions (in damp locations or while wearing wet  
clothing; on metal structures such as floors, gratings or  
scaffolds; when in cramped positions such as sitting,  
kneeling or lying, if there is a high risk of unavoidable or  
accidental contact with the workpiece or ground) use  
the following equipment:  
FUMES AND GASES  
can be dangerous.  
5.a. Welding may produce fumes and gases  
hazardous to health. Avoid breathing these  
• Semiautomatic DC Constant Voltage (Wire) Welder.  
• DC Manual (Stick) Welder.  
• AC Welder with Reduced Voltage Control.  
fumes and gases.When welding, keep  
your head out of the fume. Use enough  
ventilation and/or exhaust at the arc to keep  
3.c. In semiautomatic or automatic wire welding, the electrode,  
electrode reel, welding head, nozzle or semiautomatic  
welding gun are also electrically “hot”.  
fumes and gases away from the breathing zone. When  
welding with electrodes which require special  
ventilation such as stainless or hard facing (see  
instructions on container or MSDS) or on lead or  
cadmium plated steel and other metals or coatings  
which produce highly toxic fumes, keep exposure as  
low as possible and below Threshold Limit Values (TLV)  
using local exhaust or mechanical ventilation. In  
confined spaces or in some circumstances, outdoors, a  
respirator may be required. Additional precautions are  
also required when welding on galvanized steel.  
3.d. Always be sure the work cable makes a good electrical  
connection with the metal being welded. The connection  
should be as close as possible to the area being welded.  
3.e. Ground the work or metal to be welded to a good electrical  
(earth) ground.  
3.f. Maintain the electrode holder, work clamp, welding cable and  
welding machine in good, safe operating condition. Replace  
damaged insulation.  
5.b. Do not weld in locations near chlorinated hydrocarbon vapors  
coming from degreasing, cleaning or spraying operations.  
The heat and rays of the arc can react with solvent vapors to  
form phosgene, a highly toxic gas, and other irritating  
products.  
3.g. Never dip the electrode in water for cooling.  
3.h. Never simultaneously touch electrically “hot” parts of  
electrode holders connected to two welders because voltage  
between the two can be the total of the open circuit voltage  
of both welders.  
5.c. Shielding gases used for arc welding can displace air and  
cause injury or death. Always use enough ventilation,  
especially in confined areas, to insure breathing air is safe.  
3.i. When working above floor level, use a safety belt to protect  
yourself from a fall should you get a shock.  
5.d. Read and understand the manufacturer’s instructions for this  
equipment and the consumables to be used, including the  
material safety data sheet (MSDS) and follow your  
employer’s safety practices. MSDS forms are available from  
your welding distributor or from the manufacturer.  
3.j. Also see Items 6.c. and 8.  
5.e. Also see item 1.b.  
IDEALARC DC-655  
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iii  
iii  
SAFETY  
WELDING SPARKS can  
cause fire or explosion.  
CYLINDER may explode  
if damaged.  
6.a. Remove fire hazards from the welding area.  
If this is not possible, cover them to prevent  
7.a. Use only compressed gas cylinders  
containing the correct shielding gas for the  
the welding sparks from starting a fire.  
Remember that welding sparks and hot  
materials from welding can easily go through small cracks  
and openings to adjacent areas. Avoid welding near  
hydraulic lines. Have a fire extinguisher readily available.  
process used and properly operating  
regulators designed for the gas and  
pressure used. All hoses, fittings, etc. should be suitable for  
the application and maintained in good condition.  
7.b. Always keep cylinders in an upright position securely  
chained to an undercarriage or fixed support.  
6.b. Where compressed gases are to be used at the job site,  
special precautions should be used to prevent hazardous  
situations. Refer to “Safety in Welding and Cutting” (ANSI  
Standard Z49.1) and the operating information for the  
equipment being used.  
7.c. Cylinders should be located:  
Away from areas where they may be struck or subjected to  
physical damage.  
6.c. When not welding, make certain no part of the electrode  
circuit is touching the work or ground. Accidental contact can  
cause overheating and create a fire hazard.  
•A safe distance from arc welding or cutting operations and  
any other source of heat, sparks, or flame.  
7.d. Never allow the electrode, electrode holder or any other  
electrically “hot” parts to touch a cylinder.  
6.d. Do not heat, cut or weld tanks, drums or containers until the  
proper steps have been taken to insure that such procedures  
will not cause flammable or toxic vapors from substances  
inside. They can cause an explosion even though they have  
been “cleaned”. For information, purchase “Recommended  
Safe Practices for the Preparation for Welding and Cutting of  
Containers and Piping That Have Held Hazardous  
Substances”, AWS F4.1 from the American Welding Society  
(see address above).  
7.e. Keep your head and face away from the cylinder valve outlet  
when opening the cylinder valve.  
7.f. Valve protection caps should always be in place and hand  
tight except when the cylinder is in use or connected for  
use.  
7.g. Read and follow the instructions on compressed gas  
cylinders, associated equipment, and CGA publication P-l,  
“Precautions for Safe Handling of Compressed Gases in  
Cylinders,” available from the Compressed Gas Association  
1235 Jefferson Davis Highway, Arlington, VA 22202.  
6.e. Vent hollow castings or containers before heating, cutting or  
welding. They may explode.  
6.f. Sparks and spatter are thrown from the welding arc. Wear oil  
free protective garments such as leather gloves, heavy shirt,  
cuffless trousers, high shoes and a cap over your hair. Wear  
ear plugs when welding out of position or in confined places.  
Always wear safety glasses with side shields when in a  
welding area.  
FOR ELECTRICALLY  
powered equipment.  
6.g. Connect the work cable to the work as close to the welding  
area as practical. Work cables connected to the building  
framework or other locations away from the welding area  
increase the possibility of the welding current passing  
through lifting chains, crane cables or other alternate circuits.  
This can create fire hazards or overheat lifting chains or  
cables until they fail.  
8.a. Turn off input power using the disconnect  
switch at the fuse box before working on  
the equipment.  
8.b. Install equipment in accordance with the U.S. National  
Electrical Code, all local codes and the manufacturer’s  
recommendations.  
6.h. Also see item 1.c.  
8.c. Ground the equipment in accordance with the U.S. National  
Electrical Code and the manufacturer’s recommendations.  
IDEALARC DC-655  
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iv  
iv  
SAFETY  
7. Quand on ne soude pas, poser la pince à une endroit isolé  
PRÉCAUTIONS DE SÛRETÉ  
de la masse. Un court-circuit accidental peut provoquer un  
échauffement et un risque d’incendie.  
Pour votre propre protection lire et observer toutes les instructions  
et les précautions de sûreté specifiques qui parraissent dans ce  
manuel aussi bien que les précautions de sûreté générales suiv-  
antes:  
8. S’assurer que la masse est connectée le plus prés possible  
de la zone de travail qu’il est pratique de la faire. Si on place  
la masse sur la charpente de la construction ou d’autres  
endroits éloignés de la zone de travail, on augmente le  
risque de voir passer le courant de soudage par les chaines  
de levage, câbles de grue, ou atres circuits. Cela peut  
provoquer des risques d’incendie ou d’echauffement des  
chaines et des câbles jusqu’à ce qu’ils se rompent.  
Sûreté Pour Soudage A L’Arc  
1. Protegez-vous contre la secousse électrique:  
a. Les circuits à l’électrode et à la piéce sont sous tension  
quand la machine à souder est en marche. Eviter tou-  
jours tout contact entre les parties sous tension et la  
peau nue ou les vétements mouillés. Porter des gants  
secs et sans trous pour isoler les mains.  
9. Assurer une ventilation suffisante dans la zone de soudage.  
Ceci est particuliérement important pour le soudage de tôles  
galvanisées plombées, ou cadmiées ou tout autre métal qui  
produit des fumées toxiques.  
b. Faire trés attention de bien s’isoler de la masse quand  
on soude dans des endroits humides, ou sur un planch-  
er metallique ou des grilles metalliques, principalement  
dans les positions assis ou couché pour lesquelles une  
grande partie du corps peut être en contact avec la  
masse.  
10. Ne pas souder en présence de vapeurs de chlore provenant  
d’opéerations de dégraissage, nettoyage ou pistolage. La  
chaleur ou les rayons de l’arc peuvent réagir avec les  
vapeurs du solvant pour produire du phosgéne (gas forte-  
ment roxique) ou autres produits irritants.  
c. Maintenir le porte-électrode, la pince de masse, le câble  
de soudage et la machine à souder en bon et sûr état  
defonctionnement.  
PRÉCAUTIONS DE SÛRETÉ POUR LES  
MACHINES À SOUDER À TRANSFOR-  
MATEUR ET À REDRESSEUR  
1. Relier à la terre le chassis du poste conformement au code  
de l’électricité et aux recommendations du fabricant. Le dis-  
positif de montage ou la piece à souder doit être branché à  
une bonne mise à la terre.  
d. Ne jamais plonger le porte-électrode dans l’eau pour le  
refroidir.  
e. Ne jamais toucher simultanément les parties sous ten-  
sion des porte-électrodes connectés à deux machines à  
souder parce que la tension entre les deux pinces peut  
être le total de la tension à vide des deux machines.  
2. Dans le cas de travail au dessus du niveau du sol, se protéger  
contre les chutes dans le cas ou on recoit un choc. Ne jamais  
enroule le câble-électrode autour de n’importe quelle partie  
du corps.  
2. Autant que possible, l’installation et l’entretien du poste  
seront effectués par un électricien qualifié.  
3. Avant de faires des travaux à l’interieur de poste, la  
debrancher à l’interrupteur à la boite de fusibles.  
3. Un coup d’arc peut être plus sévère qu’un coup de soliel,  
donc:  
4. Garder tous les couvercles et dispostifis de sûreté à leur  
place.  
a. Utiliser un bon masque avec un verre filtrant approprié  
ainsi qu’un verre blanc afin de se protéger les yeux du  
rayonnement de l’arc et des projections quand on soude  
ou quand on regarde l’arc.  
b. Porter des vêtements convenables afin de protéger la  
peau de soudeur et des aides contre le rayonnementde  
l’arc.  
c. Protéger l’autre personnel travaillant à proximité au  
soudage à l’aide d’écrans appropriés et non-inflamma-  
bles.  
4. Des gouttes de laiter en fusion sont émises de l’arc de  
soudage. Se protéger avec es vêtements de protection libres  
de l’huile, tels que les gants en cuir, chemise épaisse, pan-  
talons sans revers, et chaussures montantes.  
5. Toujours porter des lunettes de sécurité dans la zone de  
soudage. Utiliser des lunettes avec écrans lateraux dans les  
zones où l’on pique le laitier.  
6. Eloigner les matériaux inflammables ou les recouvrir afin de  
prévenir ttout risque d’incendie dû étincelles.  
IDEALARC DC-655  
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v
v
MASTER TABLE OF CONTENTS FOR ALL SECTIONS  
RETURN TO MAIN INDEX  
Page  
Safety.................................................................................................................................................i-iv  
Installation.............................................................................................................................Section A  
Technical Specifications .............................................................................................................A-2  
Safety Precautions......................................................................................................................A-4  
Select Suitable Location (Stacking, Tilting, Lifting) ....................................................................A-4  
Electrical Input Connections.......................................................................................................A-4  
Reconnect Procedure.................................................................................................................A-5  
Output Connections....................................................................................................................A-6  
Operation...............................................................................................................................Section B  
Safety Precautions......................................................................................................................B-2  
General Description....................................................................................................................B-3  
Controls and Settings.................................................................................................................B-4  
Case Back Connections.............................................................................................................B-6  
Auxiliary Power...........................................................................................................................B-6  
Machine Protection.....................................................................................................................B-6  
Welding Performance .................................................................................................................B-8  
Accessories...........................................................................................................................Section C  
Maintenance .........................................................................................................................Section D  
Safety Precautions......................................................................................................................D-2  
General Maintenance..................................................................................................................D-2  
General Component Locations...................................................................................................D-3  
Theory of Operation .............................................................................................................Section E  
Troubleshooting and Repair.................................................................................................Section F  
How to Use Troubleshooting Guide............................................................................................F-2  
PC Board Troubleshooting Procedures ......................................................................................F-3  
Troubleshooting Guide................................................................................................................F-4  
Test Procedures ........................................................................................................................F-13  
Oscilloscope Waveforms ..........................................................................................................F-43  
Replacement Procedures..........................................................................................................F-49  
Retest After Repair....................................................................................................................F-57  
Electrical Diagrams............................................................................................................. Section G  
Parts Manual............................................................................................................................... P-317  
IDEALARC DC-655  
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Section A-1  
Section A-1  
TABLE OF CONTENTS  
- INSTALLATION SECTION -  
Installation.............................................................................................................................Section E  
Technical Specifications - Idealarc DC-655 ...............................................................................A-2  
Graphic Symbols that Appear on Rating Plate ..........................................................................A-3  
Safety Precautions......................................................................................................................A-4  
Select Suitable Location.............................................................................................................A-4  
Stacking................................................................................................................................A-4  
Tilting....................................................................................................................................A-4  
Electrical Input Connections.......................................................................................................A-4  
Fuse and Wire Sizes.............................................................................................................A-4  
Ground Connection..............................................................................................................A-4  
Input Power Supply Connections ........................................................................................A-5  
Reconnect Procedure.................................................................................................................A-5  
Output Connections ...................................................................................................................A-6  
Electrode and Work Cables..................................................................................................A-6  
Auxiliary Power and Control Connections ...........................................................................A-7  
Auxiliary Power Table.....................................................................................................A-7  
115VAC Duplex Receptacle...........................................................................................A-7  
230V Receptacle............................................................................................................A-7  
14 Pin MS Type Receptacle...........................................................................................A-7  
Terminal Strips ...............................................................................................................A-8  
IDEALARC DC-655  
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A-2  
A-2  
INSTALLATION  
TECHNICAL SPECIFICATIONS – DC-655  
INPUT - THREE PHASE ONLY  
Input Current at Rated Output  
100% Duty Cycle 60% Duty Cycle  
Standard  
Voltage  
Code  
Number  
122/61  
150/75  
230/460/60  
230/460/575/60  
208/416/60  
460/60  
10501  
10502  
10503  
10504  
10505  
10506  
10507  
10508  
10509  
10510  
122/61/49  
135/67.5  
61  
150/75/60  
166/83  
75  
49  
60  
575/60  
122/70  
74/56  
64  
140/70  
68  
150/86  
90/69  
78  
172/86  
83  
230/400/50/60*  
380/500/50/60*  
440/50/60  
200/400/50/60  
415/50/60  
RATED OUTPUT  
Duty Cycle  
100% Duty Cycle  
NEMA Class I (100)*  
60% Duty Cycle  
Amps  
650  
Volts at Rated Amperes  
44  
815  
44  
OUTPUT  
Voltage Range  
Current Range  
Maximum Open Circuit Voltage  
46 CV Mode  
Auxiliary Power  
See the OPERATION section for  
Auxiliary Power  
13-44 DC  
50-815  
68 CC Mode  
information by model  
RECOMMENDED INPUT WIRE AND FUSE SIZES  
TYPE 80°C  
COPPER WIRE GROUND WIRE  
Copper  
INPUT  
VOLTAGE /  
FREQUENCY  
HERTZ  
INPUT AMPERE  
RATING ON  
NAMEPLATE  
(SUPER LAG)  
OR BREAKER  
SIZE (AMPS)1  
IN CONDUIT  
IN CONDUIT  
AWG(IEC-MM2) SIZES AWG(IEC-MM2) SIZES  
40°C (104°F) Ambient  
208  
230  
416  
460  
575  
200  
230  
380  
400  
415  
440  
500  
60  
60  
60  
60  
60  
50/60  
50/60  
50/60  
50/60  
50/60  
50/60  
50/60  
135  
122  
67.5  
61  
1 (43)  
1 (43)  
6 (14)  
6 (14)  
8 (8.4)  
1/0 (54)  
1 (43)  
4 (21)  
4 (21)  
6 (14)  
6 (14)  
6 (14)  
4 (21)  
4 (21)  
6 (14)  
6 (14)  
8 (8.4)  
4 (21)  
4 (21)  
6 (14)  
6 (14)  
6 (14)  
6 (14)  
6 (14)  
250 Amp  
225 Amp  
125 Amp  
110 Amp  
90 Amp  
250 Amp  
225 Amp  
125 Amp  
125 Amp  
110 Amp  
110 Amp  
110 Amp  
49  
140  
122  
74  
70  
68  
64  
56  
PHYSICAL DIMENSIONS  
HEIGHT  
27.5 in  
699 mm  
WIDTH  
22.2 in  
564 mm  
DEPTH  
38.0 in  
965 mm  
WEIGHT  
720 lbs.  
326 kg.  
* European models meet IEC974-1 standards.  
1
Also called “inverse time” or “thermal/magnetic” circuit breakers; circuit breakers which have a delay in tripping action that decreases as the magnitude of the current increases.  
IDEALARC DC-655  
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A-3  
A-3  
INSTALLATION  
GRAPHIC SYMBOLS THAT APPEAR ON  
RATING PLATE (LOCATED ON CASE BACK)  
Constant Voltage Output  
3 Phase transformer with  
rectified DC output  
Characteristics  
INPUT POWER  
THREE PHASE  
GMAW  
FCAW  
Designates welder complies with  
National Electrical Manufacturers  
Association requirements EW 1  
Class I with 100% duty cycle at  
650Amps output. (Domestic,  
Canadian, and Export models)  
Designates welder can be used  
in environments with increased  
hazard of electric shock.  
(European models)  
S
NEMA EW 1 (100%)  
Designates welder complies with  
low voltage directive and with  
EMC directive. (European  
models)  
CE  
Designates welder complies with  
International  
Electrotechnical  
IEC 974-1  
Commission requirements 974-1.  
(European Models)  
Designates welder complies with  
both Underwriters Laboratories  
(UL) standards and Canadian  
Standards Association (CSA)  
standards. (Canadian Model)  
R
Designates the degree of envi-  
ronmental protection provided by  
the power sources enclosure.  
NRTL/C  
IP-23  
Designates welder complies with  
Underwriters Laboratories (UL)  
standards. (Domestic Models)  
R
Constant Current Output  
Characteristics  
NRTL  
SMAW  
SAW  
U
o
Open Circuit Output Voltage  
Input Voltage Rating(s)  
Input Current Rating(s)  
U
1
I
1
X
Output Duty Cycle Rating(s)  
Output Voltage Rating(s)  
U
2
I
Output Current Rating(s)  
2
IDEALARC DC-655  
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A-4  
A-4  
INSTALLATION  
Read this entire installation section  
before you start installation.  
INPUT  
CONTACTOR (CR1)  
INPUT POWER SUPPLY  
CABLE WITH BUSHING  
OR BOX CONNECTOR  
SAFETY PRECAUTIONS  
WARNING  
RECONNECT  
PANEL ASSEMBLY  
ELECTRIC SHOCK can kill.  
• Only qualified personnel should  
perform this installation.  
Turn the input power OFF at the  
disconnect switch or fuse box  
before working on this equipment.  
Turn the Power Switch on the DC-655 “OFF” before  
connecting or disconnecting output cables, wire  
feeder or remote connections, or other equipment.  
FIGURE A.1 - ELECTRICAL INPUT CONNECTIONS  
• Do not touch electrically hot parts.  
Use input wire sizes that meet local electrical codes or  
see the Technical Specifications page in this manual.  
• Always connect the Idealarc DC-655 grounding ter-  
minal (located on the welder near the reconnect  
panel) to a good electrical earth ground.  
Input power supply entry is through the hole in the  
Case Back Assembly. See Figure A.1 for the location  
of the machine’s input cable entry opening, Input  
Contactor (CR1), and reconnect panel.  
SELECT SUITABLE LOCATION  
FUSE AND WIRE SIZES  
Place the welder where clean cooling air can freely cir-  
culate in through the front louvers and out through the  
rear louvers. Dirt, dust or any foreign material that can  
be drawn into the welder should be kept at a mini-  
mum. Failure to observe these precautions can result  
in excessive operating temperatures and nuisance  
shut-downs.  
Protect the input circuit with the super lag fuses or  
delay type circuit breakers listed on the Technical  
Specifications page of this manual for the machine  
being used. They are also called inverse time or ther-  
mal/magnetic circuit breakers.  
DO NOT use fuses or circuit breakers with a lower amp  
rating than recommended. This can result in “nui-  
sance” tripping caused by inrush current even when  
machine is not being used for welding at high output  
currents.  
STACKING  
The DC-655 may be stacked three-high provided the  
bottom machine is on a stable, hard, level surface. Be  
sure that the two pins in the roof fit into the slots in the  
base of the DC-655 above it.  
GROUND CONNECTION  
Ground the frame of the machine.  
terminal marked with the symbol is located inside  
A ground  
TILTING  
Do not place the machine on a surface that is inclined  
enough to create a risk of the machine falling over.  
the case back of the machine near the input contactor.  
Access to the input box assembly is at the upper rear  
of the machine. See your local and national electrical  
codes for proper grounding methods. Use grounding  
wire sizes that meet local electrical codes or see the  
Technical Specifications page in this manual.  
ELECTRICAL  
INPUT CONNECTIONS  
Before installing the machine check that the input sup-  
ply voltage, phase, and frequency are the same as the  
voltage, phase, and frequency as specified on the  
welder nameplate.  
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A-5  
A-5  
INSTALLATION  
INPUT POWER SUPPLY CONNECTIONS  
RECONNECT PROCEDURE  
A qualified electrician should connect the input power  
supply leads.  
WARNING  
Electric Shock Can Kill  
1. Follow all national and local electrical codes.  
2. Use a three-phase line.  
• Disconnect input power before per-  
forming this procedure.  
3. Remove the input access door at upper rear of the  
machine.  
4. Follow input supply connection diagram located  
on the inside of the door.  
Multiple voltage machines are shipped connected to  
the highest input voltage listed on the machine’s rating  
plate. Before installing the machine, check that the  
reconnect panel in the input box assembly is connect-  
ed for the proper voltage.  
5. Connect the three-phase AC power supply leads  
L1, L2, and L3 to the input contactor  
terminals in the input box assembly. See Figure  
A.1.  
CAUTION  
Failure to follow these instructions can cause immedi-  
ate failure of components within the machine.  
To reconnect a multiple voltage machine to a different  
voltage, remove input power and follow the input con-  
nection diagram located on the inside of case back  
input access door.  
1. For dual voltage sample machine reconnect  
instructions, see Figure A.2.  
DUAL VOLTAGE MACHINE  
Do not operate with covers  
removed  
Do not touch electrically live parts  
INPUT SUPPLY CONNECTION DIAGRAM  
IMPORTANT: CHANGE LINK POSITIONS AND CONTROL TRANSFORMER CONNECTIONS.  
NOTE: MACHINES ARE SHIPPED FROM FACTORY CONNECTED FOR OVER 300 VOLTS  
Disconnect input power before  
Only qualified persons should install,  
use or service this equipment  
servicing  
CONNECTION FOR HIGHEST RATING PLATE VOLTAGE  
1. TURN OFF THE INPUT POWER USING THE DISCONNECT SWITCH AT THE FUSE BOX.  
2. DISCONNECT AND INSULATE THE H2 LEAD TERMINAL WITH TAPE TO PROVIDE AT  
LEAST 600 VOLT INSULATION.  
CR1  
W
L3  
3. CONNECT L1, L2  
&
L3 INPUT SUPPLY LINES AND H1  
&
H3 CONTROL TRANSFORMER  
INPUT  
LINES  
V
L2  
LEADS TO THE INPUT SIDE OF CR1 CONTACTOR AS SHOWN.  
CONTACTOR  
U
4. CONNECT TERMINAL MARKED  
CODES.  
TO GROUND PER LOCAL AND NATIONAL ELECTRIC  
L1  
H1  
GND  
5. MOUNT THE LINKS IN THE POSITIONS SHOWN; DOUBLE OR TRIPLE STACK THE LINKS  
IN THREE POSITIONS. LOOP THE FLEX LEAD IN THE POSITION SHOWN; POSITIONING  
THE LUGS TO MAINTAIN MAXIMUM CLEARANCE TO THE LINKS. INSTALL AND TIGHTEN  
ALL OF THE HEX NUTS.  
H2  
H3  
CONTROL  
TRANSF.  
LINKS  
CONNECTION FOR LOWEST RATING PLATE VOLTAGE  
1. TURN OFF THE INPUT POWER USING THE DISCONNECT SWITCH AT THE FUSE BOX.  
2. DISCONNECT AND INSULATE THE H3 LEAD TERMINAL WITH TAPE TO PROVIDE AT  
LEAST 600 VOLT INSULATION.  
CR1  
W
V
L3  
L2  
L1  
INPUT  
LINES  
3. CONNECT L1, L2  
&
L3 INPUT SUPPLY LINES AND H1  
&
H2 CONTROL TRANSFORMER  
LEADS TO THE INPUT SIDE OF CR1 CONTACTOR AS SHOWN.  
CONTACTOR  
U
4. CONNECT TERMINAL MARKED  
CODES.  
TO GROUND PER LOCAL AND NATIONAL ELECTRIC  
H1  
GND  
5. MOUNT THE LINKS IN THE POSITIONS SHOWN. CONNECT THE FLEX LEAD AS SHOWN;  
POSITIONING THE LUGS TO MAINTAIN MAXIMUM CLEARANCE TO THE LINKS.  
INSTALL AND TIGHTEN ALL OF THE HEX NUTS.  
H3  
H2  
CONTROL  
TRANSF.  
D-UF  
LINKS  
THE LINCOLN ELECTRIC CO., CLEVELAND OHIO U.S.A.  
M18225  
FIGURE A.2 - DUAL VOLTAGE MACHINE RECONNECTION PROCEDURE  
IDEALARC DC-655  
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A-6  
A-6  
INSTALLATION  
2. Connect the electrode cable to the positive terminal  
marked “+”.  
OUTPUT CONNECTIONS  
ELECTRODE AND WORK CABLES  
Use the shortest possible cable lengths. See Table A.1  
for recommended cable sizes based on length.  
3. Remove the terminal strip access cover panel on  
the lower case front. Refer to Figure A.3 for the  
location.  
4. Work Sense lead #21 from the 14 Pin MS-recepta-  
cle must be connected to “-21”on the terminal strip.  
Note: This is how the DC-655 is shipped from the  
factory.  
TABLE A.1  
Cable Sizes for Combined Lengths of Copper  
Electrode and Work Cable  
Cable Length  
ft. (m)  
Parallel Cables  
Cable Size  
5. Replace the terminal strip access cover panel.  
0 (0)  
to 100 (30.4)  
2
2
2
2/0 ( 70mm2)  
3/0 ( 95mm2)  
4/0 (120mm2)  
100 (30.4) to 200 (60.8)  
200 (60.8) to 250 (76.2)  
For Negative Polarity:  
The output terminals are located at the lower front of  
the welder behind a hinged door. Refer to Figure A.3.  
Route the welding cables through the slotted strain  
reliefs of the base to the welding terminals.  
1. Connect the electrode cable to the appropriate high  
inductance (-) terminal (marked "  
or to the low inductance (-) terminal (marked  
") if using NR203Ni 1% electrode.  
")  
"
LOW INDUCTANCE TERMINAL  
2. Connect the work cable to the positive terminal  
marked “+”.  
On the DC-655, the inside right Negative (-) output ter-  
minal is lower choke inductance. This terminal is  
presently only recommended for CV mode welding  
with NR203Ni 1% negative polarity procedures.. All  
other processes are to be welded using the outside  
right Negative (-) output terminal with higher choke  
inductance. CC mode processes must use high  
inductance.  
3. Remove the terminal strip access cover panel on the  
lower case front. Refer to Figure A.3 for the location.  
4. Work Sense lead #21 from the 14 Pin MS-recepta-  
cle must be connected to “+21”on the terminal  
strip.  
5. Replace the terminal strip access cover panel.  
For Positive Polarity:  
1. Connect the work cable to the high inductance (-)  
terminal (marked "  
").  
14 PIN MS RECEPTACLE  
POSITIVE  
OUTPUT  
TERMINAL  
LOW INDUCTANCE  
HIGH INDUCTANCE  
NEGATIVE OUTPUT  
NEGATIVE OUTPUT  
TERMINAL  
TERMINAL  
TERMINAL STRIP  
COVER PANEL  
FIGURE A.3 - OUTPUT CONNECTIONS  
IDEALARC DC-655  
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A-7  
A-7  
INSTALLATION  
14-PIN MS TYPE RECEPTACLE  
AUXILIARY POWER AND  
CONTROL CONNECTIONS  
(For MS3106A-20-27PX Plug. L.E.C. Part #S12020-32)  
Located at the lower front of the welder behind a  
hinged door is a 115 VAC duplex receptacle for auxil-  
iary power (Domestic and Canadian Models only) and  
a 14-pin MS type receptacle for connection of auxiliary  
equipment such as wire feeders. Also, terminal strips  
with 115 VAC and connections for auxiliary equipment  
are located behind the access panel on the lower case  
of the welder. A 220 VAC receptacle for a water cooler  
(European and Export Models only) is located on the  
case back.  
Refer to the Figure A.4 for the available circuits in the  
14-pin receptacle.  
42 VAC is available at receptacle pins I and K. A 10  
amp circuit breaker protects this circuit.  
115 VAC is available at receptacle pins A and J  
(Domestic, Canadian and Export Models). This circuit  
is protected by a circuit breaker (see Auxiliary Power  
Table). Note that the 42 VAC and 115 VAC circuits are  
electrically isolated from each other. However, on the  
European model one line of the 115 VAC is connected  
to chassis ground.  
AUXILIARY POWER TABLE  
Voltage and Circuit Breaker Ratings at Auxiliary Power  
Connections for Various Models  
FIGURE A.4 - FRONT VIEW OF 14-PIN  
CONNECTOR RECEPTACLE  
Auxiliary  
Power  
Connections  
Domestic  
Models  
(60Hz)  
Canadian  
Model  
European  
Models  
Export  
Models  
(230/460/575V/60 Hz) (50/60 Hz) (50/60 Hz)  
K=42  
At Duplex  
Receptacle  
115V 20A  
115V 20A  
115V 20A  
42V 10A  
115V 15A  
115V 15A  
115V 15A  
42V 10A  
No Duplex No Duplex  
J=31  
I=41  
A=32  
B=GND  
Terminal strip  
terminals 31 & 32  
115V 15A  
115V 15A  
L
N
MS-Receptacle  
pins A & J  
Open Circuit 115V 15A  
C=2  
D=4  
E=77  
H=21  
MS-Receptacle  
pins I & K  
42V 10A  
220V 2A  
42V 10A  
220V 2A  
G=75  
F=76  
At 220V  
Receptacle  
No Receptacle  
No Receptacle  
M
PIN  
LEAD NO.  
FUNCTION  
A
B
C
D
E
F
32  
GND  
2
115 VAC  
115 VAC DUPLEX RECEPTACLE (DOMESTIC AND  
CANADIAN MODELS ONLY)  
Chassis Connection  
Trigger Circuit  
Trigger Circuit  
Output Control  
Output Control  
Output Control  
The 115 VAC duplex receptacle is protected by a cir-  
cuit breaker located below the receptacle (see  
Auxiliary Power Table). Receptacle is a NEMA 5-20R  
(protected by a 20 amp breaker) on Domestic Models  
and a NEMA 5-15R (protected by a 15 amp breaker) on  
Canadian Models.  
4
77  
76  
75  
G
H
I
21  
41  
Work Sense Connection2  
42 VAC  
J
K
L
M
N
31  
42  
---  
---  
---  
115 VAC1.  
42 VAC  
---  
---  
---  
230 VAC RECEPTACLE (EUROPEAN AND EXPORT  
MODELS ONLY)  
A Continental European receptacle is located on the  
rear panel for supplying 220 VAC to a water cooler. The  
receptacle has a protective cover to prevent acciden-  
tal contact and is a Schuko type. The circuit is pro-  
tected by a 2 amp circuit breaker also located on the  
rear panel. This circuit is electrically isolated from all  
other circuits, but on the European Models one line is  
connected to chassis ground.  
1.  
2.  
115VAC circuit is not present in the 14-pin connector on IEC 974-  
1 European models.  
As shipped from the factory Lead #21 from the 14-pin connector is  
connected to “-21” on the terminal strip. This is the configuration for  
positive welding. If welding negative polarity, connect lead #21 to  
the “+21” connection point on the terminal strip.  
IDEALARC DC-655  
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A-8  
A-8  
INSTALLATION  
TERMINAL STRIPS  
Terminal strips are available behind the cover panel on  
the lower case front to connect wire feeder control  
cables that do not have a 14-Pin MS-type connector.  
Refer to Figure A.3 for the location of this cover panel.  
These terminals supply the connections as shown in  
the following Terminal Strip charts. See Auxiliary  
Power Table for rating of circuit breaker in 115 VAC cir-  
cuit. Remove a plug button from the terminal strip  
cover and install an appropriate strain relief clamp for  
the cable being used. NOTE: There are two work  
sense lead connection points on the terminal strip.  
Connect both the work sense lead #21 from the 14-pin  
connector and #21 lead of the control cable to “-21”  
when welding positive polarity or to “+21” when weld-  
ing negative polarity.  
TERMINAL STRIP 1 (T.S.1)  
Lead No.  
Function  
75  
76  
77  
Output Control  
Output Control  
Output Control  
TERMINAL STRIP 2 (T.S.2)  
Lead No.  
Function  
+21  
-21  
41  
4
2 (42 VAC)  
31  
32  
Work Connection  
Work Connection2  
42 VAC  
Trigger Circuit  
Trigger Circuit (42 VAC)  
115 VAC1  
115 VAC1  
1
115 VAC circuit is also present on IEC 974-1 European models.  
2 If connecting a feeder cable directly to the terminal strip, Lead #21  
from the cable is connected to “-21” on the terminal strip for positive  
welding. If welding negative polarity, connect lead #21 to the “+21”  
connection point on the terminal strip.  
IDEALARC DC-655  
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Section B-1  
Section B-1  
TABLE OF CONTENTS  
- OPERATION SECTION -  
Operation...............................................................................................................................Section B  
Safety Precautions......................................................................................................................B-2  
General Description....................................................................................................................B-3  
Recommended Processes and Equipment .........................................................................B-3  
Design Features and Advantages........................................................................................B-3  
Welding Capability................................................................................................................B-3  
Controls and Settings.................................................................................................................B-4  
Case Back Connections.............................................................................................................B-6  
220 VAC Auxiliary Receptacle..............................................................................................B-6  
220 VAC 2 Amp Circuit Breaker...........................................................................................B-6  
Auxiliary Power ...........................................................................................................................B-6  
Machine Protection.....................................................................................................................B-6  
Thermal Fan Control.............................................................................................................B-6  
Fan Motor Fuse....................................................................................................................B-6  
Machine Shutdown ..............................................................................................................B-6  
Thermal Shutdown...............................................................................................................B-7  
Over Current Protection Shutdown......................................................................................B-7  
Remote Control Leads Fault Protection Shutdown.............................................................B-7  
Shorted Rectifier Fault Protection........................................................................................B-7  
Idle Shutdown Timer ............................................................................................................B-7  
Welding Performance .................................................................................................................B-8  
Low Inductance Terminal .....................................................................................................B-8  
CV Mode Current Limiting....................................................................................................B-8  
CC Mode Arc Force .............................................................................................................B-8  
CC Mode Hot Start ..............................................................................................................B-8  
CC Mode Arc Gouging.........................................................................................................B-8  
IDEALARC DC-655  
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B-2  
B-2  
OPERATION  
OPERATING INSTRUCTIONS  
Read and understand this entire section of operating  
instructions before operating the machine.  
SAFETY PRECAUTIONS  
WARNING  
ELECTRIC SHOCK can kill.  
• Do not touch electrically live parts or  
electrodes with your skin or wet cloth-  
ing.  
• Insulate yourself from the work and ground.  
• Always wear dry, insulating gloves.  
FUMES AND GASES can be  
dangerous.  
• Keep your head out of fumes.  
• Use ventilation or exhaust to remove fumes from  
breathing zone.  
CUTTING SPARKS can cause  
fire or explosion.  
• Keep flammable material away.  
• Do not cut containers that have held combustibles.  
ARC RAYS  
can burn.  
• Wear eye, ear, and body protection.  
Observe additional Safety Guidelines detailed in  
the beginning of this manual.  
IDEALARC DC-655  
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B-3  
B-3  
OPERATION  
• Power on/off switch with pilot light and thermostat  
tripped indicator light.  
GENERAL DESCRIPTION  
The DC-655 is an energy efficient constant voltage DC  
power source that produces outstanding arc charac-  
teristics for multiple CV or CC welding processes.  
• Full range output voltage (CV mode) and current (CC  
mode) control for easy operation.  
• Panel switches behind a latched front panel for  
remote or local output control, output on or remote  
selection, and CC, CV Sub-arc or CV MIG mode  
selection.  
Four models are available:  
Domestic - all 60 Hertz models except  
230/460/575v.  
NEMA Class 1 rated  
• Panel knob settable CC arc force control with built-  
in adjustable “Hot Start”.  
Canadian - 230/460/575v 60 Hertz  
NEMA Class 1 rated  
• High efficiency output, and selectable “sleep mode”  
idle mode timer which shuts down input power if not  
used for extra energy conservation.  
European - 50/60 Hertz models “CE” qualified  
and rated for IEC 974-1  
Export - 50/60 Hertz models NEMA Class 1 rated  
• Fan as needed (F.A.N.). Solid state thermally con-  
trolled fan operates cooling fan only when required.  
Minimizes power consumption, operating noise and  
dust intake.  
RECOMMENDED PROCESSES AND  
EQUIPMENT  
The DC-655 is designed for CV or CC processes.  
• Hinged cover to protect output terminals and auxil-  
iary connections.  
• Electronic and thermostatic protection for current  
overload and excessive temperatures.  
CV processes include: GMAW (MIG) and FCAW (flux-  
cored) welding, plus the capability of CV submerged  
arc welding and air carbon arc gouging. It produces  
outstanding welding performance with a single range  
full output control knob.  
• 42 VAC, 10 amp auxiliary power available for the wire  
feeder; circuit breaker protected.  
• 115 VAC, auxiliary power available for the wire feed-  
er; circuit breaker protected. 20 amp breaker on  
Domestic model and 15 amp breaker on Canadian,  
European, and Export Models.  
CC processes include stick welding, CC submerged  
arc and superior air carbon arc gouging with up to 3/8”  
(10 mm) diameter carbons. The same single range full  
output control knob is used and paralleling capability  
is provided.  
• 115 VAC duplex plug receptacle available on  
Domestic and Canadian Models. 20 amp breaker on  
Domestic Models and 15 amp breaker on Canadian  
Model.  
The DC-655 is recommended for use with Lincoln’s  
DH-10 or LN-10 as well as the LN-7*, LN-7 GMA*, LN-  
742, LN-8*, LN-9*, LN-9 GMA*, LN-23P and LN-25  
semiautomatic wire feeders. It is also recommended  
for use with the NA-3, NA-5 and NA-5R automatic  
feeders. “Cold starting” for sub-arc or across arc  
“touch-sensing” can be used.  
• 220 VAC receptacle on European and Export models  
for connecting to a water cooler. Protected by 2 amp  
breaker.  
• Single MS-type (14-pin) connection for wire feeder.  
* The 14-pin MS receptacle on the European models  
does not provide 115 VAC for these feeders; 115  
VAC must be obtained from terminal strip.  
• Optional Field Installed Digital or Analog Voltmeter/  
Ammeter kits are available.  
• Optional dual feeder kit for like polarity connection of  
two wire feeders. Easy panel installation.  
Two DC-655’s may be paralleled in a “master” and  
“slave” interconnection using the K1611-1 Paralleling  
kit.  
• Optional Dual Process Switch for two processes  
with polarity change and electrical isolation.  
DESIGN FEATURES AND  
ADVANTAGES  
• Separate output terminals for selecting high or low  
inductance as recommended for the welding  
process.  
WELDING CAPABILITY  
The DC-655 has the following Output and Duty Cycle  
based on operation for a 10 minute period:  
650 Amps, 44 Volts at 100%  
815 Amps, 44 Volts at 60%  
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B-4  
B-4  
OPERATION  
CONTROLS AND SETTINGS  
All operator controls and adjustments are located on the case front of the DC-655. Refer to Figures B.1, and B.2  
and corresponding explanations.  
8
9
2
3
1
DC-655  
7
6
5
4
FIGURE B.1 CONTROL PANEL CONTROLS  
1. INPUT  
gle switch turns the machine on or off. Putting the  
switch in the ON position energizes the  
POWER ON/OFF SWITCH - This tog-  
remote device such as a wire feeder closes the #2 and  
#4 circuit in the MS-receptacle or terminal strip. When  
this switch is in the ON position the machine’s output  
terminals will be electrically energized all the time.  
machine’s input contactor applying input power to  
the machine. Switching the switch to the OFF  
position de-energizes the input contactor. This  
switch is also used to reset a machine shutdown.  
(See Machine Shutdown section)  
5. LOCAL/REMOTE CONTROL SWITCH - When  
this switch is set to the LOCAL  
position, con-  
trol of the output voltage is via the output control  
on the DC-655’s control panel. When this switch is  
2. PILOT LIGHT - When the power switch is in the  
ON position the machine’s white pilot light will illu-  
minate. If the input contactor de-energizes the  
machine in a shutdown situation, the pilot will still  
illuminate. In this situation it will be necessary to  
reset the machine by switching the power switch to  
the OFF then ON position. (See Machine  
Shutdown section)  
set to the remote  
position, control is through a  
remote source such as a wire feeder via the #75,  
#76, and #77 leads in the MS-receptacle or termi-  
nal strip.  
6. CC STICK/CV SUBARC/CV MIG MODE SWITCH -  
This switch selects the proper welding characteris-  
tics for the process being used:  
CC Stick provides a constant current output  
characteristic through the 50 to 815 amp  
range. The current is adjusted within this  
range by the Output Control dial. The open  
circuit (no load) voltage will be about 68 volts  
in this mode.  
3. OUTPUT  
CONTROL - This control provides  
continuous control of the machine’s output from  
minimum to maximum as it is rotated clockwise.  
The CV mode voltage range of control is 13 to 44V.  
The CC mode current range of control is 50 to  
815A.  
This mode is used for stick welding (SMAW)  
and CC air carbon-arc gouging, and employs  
a “Hot Start” feature and an Arc Force Control.  
4. OUTPUT TERMINALS ON/REMOTE - When this  
switch is in the REMOTE  
position, the DC-655’s  
output terminals will be electrically “cold” until a  
IDEALARC DC-655  
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B-5  
B-5  
OPERATION  
CC mode may also be used for CC submerged arc  
with appropriate arc-sensing CC(VV) wire feeders  
if arc force is set high enough. Refer to Welding  
Performance section.  
7. ARC FORCE CONTROL - This control is only func-  
tional in CC Stick mode. It prevents “stubbing” of  
the electrode by providing the extra weld current  
that linearly increases as the welding voltage  
decreases below a level determined by the setting  
of the constant current control.  
CV MIG provides a constant voltage output char-  
acteristic through the 13 to 44 volt range. The volt-  
age is adjusted within this range by the Output  
Control dial.  
The Arc Force control knob, located behind the  
latched cover, adjusts arc force from “Min” (no cur-  
rent increase) to “Max” (higher short circuit current).  
The “mid” position (#5) is recommended for most  
CC welding. Refer to the Welding Performance  
Section.  
The dynamic characteristics of this mode are ideal  
for open arc processes including, MIG/MAG  
(GMAW), Innershield®, and other cored wire  
(FCAW) processes. Faster travel submerged arc  
processes and CV air carbon-arc gouging may  
also use this mode. Refer to the Welding  
Performance section.  
8. OPTIONAL VOLTMETER & AMMETER - Digital or  
analog meter kits are available as field installed  
options. Refer to the Accessories Section of this  
manual.  
CV Sub-Arc provides the same constant voltage  
output control range as CV MIG, but the dynamic  
characteristics of this mode make possible  
improved CV (constant wire speed) submerged arc  
welding. This improved process is most notice-  
able on high deposition slow travel speed welds.  
Fast travel, narrow bead subarc welds will have  
better performance in CV MIG mode.  
9. THERMAL PROTECTION LIGHT  
- If the  
machine overheats due to lack of proper air flow  
through the machine or due to exceeding the  
machine’s duty cycle, thermostats will disable the  
welding output and this light will illuminate. Input  
power is still applied to the machine and the cool-  
ing fan will continue to run. When the machine  
cools the welding output will resume.  
FIGURE B.2 LOWER CASE FRONT CONTROLS & CONNECTIONS  
1
2
3
4
5
7
6
1. 115 VAC DUPLEX RECEPTACLE (Domestic and  
Canadian Models) This receptacle provides up to  
20 amps of 115 VAC auxiliary power on the  
2. 115 VAC CIRCUIT BREAKER  
- This breaker  
protects the 115 VAC auxiliary circuits located in  
the duplex receptacle, terminal strip and MS-  
receptacle. Breaker is rated 20 amps on Domestic  
Models and 15 amps on all other models.  
Domestic Models  
Canadian Model.  
and up to 15 amps on the  
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B-6  
B-6  
OPERATION  
3. 42 VAC 10 AMP CIRCUIT BREAKER  
- This  
DC-655 machines can also supply 115 volt AC auxil-  
iary power through the wire feeder receptacle. A 20  
amp circuit breaker on the Domestic model, and a 15  
amp on the Canadian and Export models protects the  
115 volt circuit from overloads. 115 VAC is not avail-  
able in the MS-receptacle on the European models.  
breaker protects the 42 VAC auxiliary circuits locat-  
ed in the terminal strip and MS-receptacle.  
4. 14-PIN MS-RECEPTACLE - This connector pro-  
vides easy connection for a wire feeder control  
cable. It provides connections for auxiliary power,  
output switching, remote output control, wire feed-  
er voltmeter sense lead and ground. Refer to 14-  
Pin MS Type Receptacle in the Installation  
Section of this manual for information about the cir-  
cuits made available at this receptacle.  
CAUTION  
Note that some types of equipment, especially pumps  
and large motors, have starting currents which are sig-  
nificantly higher than their running current. These high-  
er starting currents may cause the circuit breaker to  
open. If this situation occurs, the user should refrain  
from using the DC-655 auxiliary power for that equip-  
ment.  
5. TERMINAL STRIP COVER PANEL - Remove this  
panel to gain access to the circuits made available  
at the terminal strip and the 4-pin receptacle for the  
optional paralleling kit. This terminal strip contains  
the same circuits as the 14-pin MS-receptacle.  
The cover also provides for installation of cable  
strain relief clamps.  
MACHINE PROTECTION  
6. POSITIVE OUTPUT TERMINAL - This output ter-  
minal is for connecting a welding cable. To change  
welding polarity and for proper welding cable size  
refer to Electrode and Work Cables in the  
Installation Section of this manual.  
THERMAL FAN CONTROL  
The machine’s cooling fan remains off when the tem-  
perature of the rectifiers and windings inside the  
machine are below that requiring air flow cooling, as  
determined by electronic monitoring of several thermal  
sensors and the welding current of the machine.  
Depending upon the operating temperature of the  
machine, the fan may remain off while welding but  
once the fan is activated, it will remain on for at least 5  
minutes to assure proper cooling. This feature saves  
energy and also minimizes the amount of dirt and  
other air borne particles being drawn into the machine.  
7. NEGATIVE OUTPUT TERMINALS - These output  
terminals are for connecting a welding cable to  
either the High Inductance or Low Inductance  
Terminal for desired arc characteristics. To change  
welding polarity and for proper welding cable size  
refer to Electrode and Work Cables in the  
Installation Section of this manual.  
CASE BACK CONNECTIONS  
FAN MOTOR FUSE  
(European Model)  
220 VAC AUXILIARY RECEPTACLE  
(European and Export Models)  
A 10 amp slow blow fuse protects the fan motor cir-  
cuit. This fuse is located inside the DC-655 mounted  
on the fan motor bracket.  
This receptacle provides up to 2 amps of 220 VAC  
auxiliary power for a water cooler.  
220 VAC 2 AMP CIRCUIT BREAKER  
(European and Export Models)  
MACHINE SHUTDOWN  
This breaker protects the 220 VAC auxiliary circuit  
located in the 220 VAC receptacle.  
The DC-655 provides shutdown modes for thermal  
over-heating, excessive load currents and faults. It  
also provides an idle timer shutdown feature for addi-  
tional operating economy.  
AUXILIARY POWER  
42 volt AC auxiliary power, as required for some wire  
feeders, is available through the wire feeder recepta-  
cle. A 10 amp circuit breaker protects the 42 volt cir-  
cuit from overloads.  
IDEALARC DC-655  
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B-7  
B-7  
OPERATION  
THERMAL SHUTDOWN  
SHORTED RECTIFIER FAULT PROTECTION  
This welder has thermostatic protection from exces-  
sive duty cycles, overloads, loss of cooling, and high  
ambient temperature. When the welder is subjected to  
an overload or loss of cooling, a thermostat will open.  
This condition will be indicated by the illumination of  
the yellow Thermostatic Protection Light on the case  
front (see Figure B.1). The fan will continue to run to  
cool the power source. No welding is possible until the  
machine is allowed to cool and the Thermostatic  
Protection Light goes out.  
If a short occurs across one of the silicon controlled  
rectifiers of the DC-655, a potentially hazardous AC  
voltage could appear across the welding output termi-  
nals, even in idle mode when no output should be pre-  
sent. If such a fault occurs, the DC-655 will shut down  
the input primary voltage to the transformer to prevent  
the fault output. Control PC board LED3, input shut-  
down light, turns on.  
If this input shutdown occurs the input power pilot  
light remains lit, since the power switch is ON and  
control power is still present. Welding output or auxil-  
iary supply output will not be present.  
OVER CURRENT PROTECTION  
SHUTDOWN  
Average Current Shutdown  
To protect the SCR’s , the DC-655 will shut down to  
essentially no output if the output current averages  
over 900 amps for about 5-6 seconds, and in less than  
0.3 seconds if averaging over 1200 amps (shorter time  
for higher current). Control PC board LED4, shutdown  
light, will turn on.  
This input shut down is reset by turning the DC-655  
input power off, then on. If the fault is not corrected  
however, the shutdown will re-occur when turning on  
the input power.  
IDLE SHUTDOWN TIMER  
For additional operating economy, the DC-655 can be  
set up to automatically shut off the primary input  
power to the main transformer after a selectable time  
(1/2 or 2 hr.) has expired without welding. The unex-  
pired timer is reset with each weld.  
This average current shut down can only be reset by  
opening the feeder gun trigger, or switching the DC-  
655 Output/Remote switch out of the “on” position.  
Peak Current Shutdown  
The idle mode timer is activated by setting Switch #1  
(left most) of the DIP Switch located on the lower-cen-  
ter of the DC-655 Control PC board. from the down  
(Off) position to the up (On) position. Setting Switch  
#2 of the DIP switch to up (On) sets the shutdown time  
to 2 hours. Setting Switch #2 of the DIP switch to  
down (Off) sets the shutdown time to 1/2 hour.  
Shutdown is reset by turning the DC-655 input power  
off, then on.  
To protect the SCRs, the DC-655 will shut down imme-  
diately to essentially no output if the peak output cur-  
rent exceeds 2500 amps (about 1800A average).  
Control PC board LED4, shutdown light, will turn on.  
This peak current shut down can be reset by turning  
the DC-655 input power off, then on.  
REMOTE CONTROL LEADS FAULT  
PROTECTION SHUTDOWN  
1
The remote control leads from the 14-pin receptacle or  
terminal strip are protected against high voltage faults  
to the electrode circuit or auxiliary voltage supplies. If  
such a fault occurs, the DC-655 will shut down the  
input primary voltage to the transformer to prevent the  
fault output. Control PC board LED3, input shutdown  
light, turns on.  
Switch #1 Timer On/Off  
(UP=ON, Down=OFF)  
1
2
3
4
DIP Switch  
If this input shutdown occurs the input power pilot  
light remains lit, since the power switch is ON and  
control power is still present. Welding output or auxil-  
iary supply output will not be present.  
Switch #2 Time selection  
(UP=2 hours, Down=1/2 hour)  
This input shut down is reset by turning the DC-655  
input power off, then on. If the fault is not corrected  
however, the shutdown will re-occur when turning on  
the input power.  
Note: See Weld Performance section  
for use of switch #3 and #4.  
1 Note on earlier machines: LED4 will turn on and output will be  
disabled if this fault occurs.  
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B-8  
B-8  
OPERATION  
As a general guideline for CC welding, set Arc Force to  
“Mid” position and increase (typically to no more than  
#7) as necessary to prevent “stubbing” or “pop-outs”  
while welding. This higher arc force is recommended  
especially for low end 6010 stick welding.  
WELDING PERFORMANCE  
LOW INDUCTANCE TERMINAL  
The inside right Negative (-) terminal is lower choke  
inductance and presently is only recommended for  
welding with NR203Ni 1% procedures. All other  
processes are to be welded using the outside right  
Negative (-) terminal with higher choke inductance.  
VOLTS  
OCV  
CV MODE CURRENT-LIMITING  
Hot Start  
CV MIG and CV Sub-Arc modes employ electronic  
current limiting to limit excessive short circuit output  
current which can result in undesirable arc character-  
istics or nuisance over current protection shutdown  
(see Machine Protection section).  
Max. Arc Force  
Min. Arc Force  
Low  
Setting  
Hi  
AMPS  
As shipped, the DC-655 is set for “Hi” current limiting,  
which maintains constant voltage until the welding  
current exceeds a level proportional to the voltage set-  
ting, then falls off linearly at about 10 volts per 100  
amps to a limited short circuit current. “Lo” current  
limiting provides the same short circuit current, but the  
arc voltage begins to linearly fall off at lower current, at  
about 5 volts per 100 amps.  
Setting  
CC OUTPUT  
CC MODE HOT START  
Hot start is built-in for CC mode stick and carbon arc  
starting. Hot Start provides an extra weld current  
“boost” at the arc strike which increases with higher  
current settings. This Hot Start level exponentially  
decays to the weld current setting in a few seconds.  
“Hi” is recommended for all CV processes, especially  
for CV subarc and CV arc gouging, but “Lo” tends to  
“soften” the arc more when welding NR203Ni 1% on  
the Low Inductance (-) terminal. If “Lo” is desired,  
switch #4(right-most) of the DIP switch located on the  
lower-center of the DC-655 Control PC board needs to  
be switched from up (Hi) position to down (Lo) posi-  
tion.  
Adjustment of the Hot Start shouldn’t be necessary,  
but an unsealed trimmer (R81) is provided on the DC-  
655 Control PC Board to adjust hot start. Full counter-  
clockwise adjustment will reduce Hot Start to zero.  
Switch #3 is for test  
VOLTS  
purposes. Keep down.  
(as shown)  
DIP Switch  
1
CC Hot Start  
Trimmer  
2
3
4
High  
Setting  
"HI" Current Limit  
"Lo" Current Limit  
Low  
Setting  
Switch #4 "Hi"CV Current  
Limit (as shown)  
Note: See Machine Shutdown section  
for use of switch #1 and #2.  
AMPS  
DC-655 Control PC Board  
CV OUTPUT  
CC MODE ARC FORCE  
CC MODE ARC GOUGING  
Arc Force provides extra weld current which linearly  
increases as the welding voltage decreases below a  
level determined by the constant current setting. The  
Arc Force control knob, located behind the latched  
cover, adjust Arc Force from “Min” (no current  
increase) to “Max” (about 9A/V increase).  
The DC-655 is rated for air carbon arc gouging with up  
to 3/8” (10mm) diameter carbons. CC mode gouging  
is often preferred over CV mode for cutting control, but  
some Arc Force may be required to avoid carbon stub-  
bing.  
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Section C-1  
Section C-1  
TABLE OF CONTENTS  
- ACCESSORIES -  
Accessories...........................................................................................................................Section C  
Field Installed Options................................................................................................................C-2  
Connection of Lincoln Electric Automatic or Semiautomatic Wire Feeders..............................C-3  
Automatic Wire Feeders.......................................................................................................C-3  
NA-3 or LT-7 (Terminal Strip) .........................................................................................C-3  
NA-5 or NA-5R (Terminal Strip) .....................................................................................C-4  
Semiautomatic Wire Feeders...............................................................................................C-6  
LN-7 (14-Pin MS Receptacle)........................................................................................C-6  
LN-7 (Terminal Strip)......................................................................................................C-7  
LN-8 or LN-9 (Terminal Strip) ........................................................................................C-8  
LN-8 or LN-9 (14-Pin MS Receptacle) ..........................................................................C-9  
DH-10 (14-Pin MS Receptacle) .....................................................................................C-9  
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C-2  
C-2  
ACCESSORIES  
REMOTE OUTPUT CONTROL  
(K775 OR K857 WITH K864 ADAPTER)  
FIELD INSTALLED OPTIONS  
K1482-1 Digital Ammeter/Voltmeter Kit - Installs  
easily to the front control panel and provides digital  
display of actual welding voltage and amperage while  
welding. (Installation instructions are included with the  
kit).  
An optional “remote output control” is available. This is  
the same remote control that is used on other Lincoln  
power sources (K775). The K775 consists of a control  
box with 28 ft (8.5m) of four conductor cable. This  
connects to terminals 75, 76, and 77 on the terminal  
strip and the case grounding screw so marked with the  
K1483-1 Analog Ammeter/Voltmeter Kit - Installs  
easily to the front control panel and provides analog  
display of actual welding voltage and amperage while  
welding. (Installation instructions are included with the  
kit).  
symbol  
on the machine. These terminals are locat-  
ed behind the cover panel on the lower connection  
panel of the DC-655. This control will give the same  
control as the output control on the machine.  
The K857 has a 6-pin MS-style connector. The K857  
requires a K864 adapter cable which connects to the  
14-pin connector on the DC-655.  
K1484-1 Dual Feeder Kit - This kit replaces the 14-  
Pin MS-receptacle panel on the lower case front of the  
DC-655. It provides two 14-Pin MS-receptacles and a  
built in transfer circuit for connecting and operating  
two like-polarity wire feeders. European DC-655 mod-  
els can only use 42V feeders with this kit. (Installation  
instructions are included with the kit).  
REMOTE CONTROL ADAPTER CABLE (K864)  
CABLE RECEPTACLE (6 SOCKET)  
TO: K857 REMOTE CONTROL  
STRAIGHT PLUG (14 PIN)  
TO POWER SOURCE  
K1485-1 Cable Hanger Bracket - Mounts over stan-  
dard lift bale of the DC-655 and provides a cable  
hanger on both sides of the power source, each side  
capable of holding up to 100 ft. of weld cable.  
(Installation instructions are included with the kit).  
CABLE RECEPTACLE (14 SOCKET)  
TO: LN-7 WIRE FEEDERS  
K1486-1 Air Filter Kit - Removable metal filter easily  
slides in and out of a bracket which mounts to the  
front of the DC-655. Filter is designed to trap 80% of  
entering particles which are 5 microns, or larger, in  
size. (Installation instructions are included with the kit).  
Cannot be used with K1528-1 Dual process switch.  
A “V” cable 12” (.30m) long to connect a K857 Remote  
Control (6 pin connector) with a wire-feeder (14-pin  
connector) and the machine (14-pin connector). If a  
remote control is used alone the wire-feeder connec-  
tion is then not used.  
K1528-1 Dual Process Switch - (Cannot be used with  
K1486-1 Air Filter Kit) The Dual-Process Switch  
mounts easily to the front of the machine and is  
designed to provide a selection between left and right  
side output terminals. Each pair of output terminals  
can be switched to either the DC-655, high or low  
inductance terminals as desired. Wire feed unit cables  
and air carbon arc cables can be connected to either  
or both sides of the box and with proper connection  
can provide polarity change with just a switch change.  
Selecting one side only energizes those output studs  
and opens the other side. Installation instructions are  
included with the switch.)  
NOTE: A dirty air filter may cause the thermal protec-  
tion of the DC-655 to prematurely activate. Remove  
and blow out, or wash and dry, the filter every two  
months, or less if in extremely dirty conditions.  
Replace if necessary.  
Undercarriage (K817P, K842) - The DC-655 is  
designed for use with the Lincoln K817P or K842  
Undercarriage. Complete installation instructions are  
included with each undercarriage. When any of the  
undercarriages are installed, the DC-655 lift bail is no  
longer functional. Do not attempt to lift the machine  
with the undercarriage attached. The undercarriage is  
designed for moving the machine by hand only.  
Mechanized towing can lead to injury and /or damage  
to the DC-655.  
K1611-1 Paralleling Kit - Provides interconnection of  
two DC-655 machines in parallel for doubling the cur-  
rent capacity of one machine. This “master” and  
“slave” connection configuration allows the “master”  
to control the balanced output of both machines.  
Individual protection circuits of both machines func-  
tion normally. (Installation instructions are included  
with the switch.)  
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C-3  
C-3  
ACCESSORIES  
The DC-655 can be used to power any of  
the following Lincoln Wire feeders:  
AUTOMATIC WIRE FEEDERS  
CONNECTING THE NA-3 OR LT-7 TO THE  
IDEALARC DC-655 (TERMINAL STRIP)  
SEMI-AUTOMATIC WIRE FEEDERS  
1. Set Idealarc DC-655 POWER toggle switch to the  
OFF (0) position.  
DH-10  
LN-9*  
LN-10  
LN-9 GMA*  
LN-23P  
LN-25  
2. Disconnect main AC input power to the Idealarc  
DC-655.  
LN-7 GMA*  
LN-742  
LN-7*  
3. Connect the wire feeder control cable leads to the  
Idealarc DC-655 terminal strip as shown in Figure  
C.1.  
LN-8*  
4. Connect the wire feeder control cable ground lead  
to the frame terminal marked  
.
AUTOMATIC WIRE FEEDERS*  
NOTE: The Idealarc DC-655 must be properly  
NA-3  
NA-5  
NA-5R  
LT-7 Tractor  
grounded.  
* European DC-655 models only provide 115VAC for these feeders at the ter-  
minal strip (TS2)  
FIGURE C.1 – NA-3 OR LT-7 WIRE FEEDER  
CONNECTION TO THE IDEALARC DC-655  
14-PIN  
RECEPTACLE  
CONNECTION OF LINCOLN ELECTRIC  
AUTOMATIC OR SEMIAUTOMATIC WIRE  
FEEDERS  
POWER SOURCE  
CONTROL CABLE  
FOR CONTROL CABLE  
WITH 14 PIN  
MS-TYPE  
PLUG CONNECTOR  
TO AUTOMATIC  
CONTROL BOX  
21  
OR  
CONTROL CABLE  
WARNING  
FOR CONTROL CABLE  
WITH TERMINAL STRIP  
LEAD CONNECTORS  
ELECTRIC SHOCK can kill.  
+
21  
-
21 41  
75 76  
77  
4
2
31 32  
• Only qualified personnel should per-  
form this installation.  
77  
76  
75  
32  
31  
2
4
Turn the input power OFF at the dis-  
connect switch or fuse box before working on this  
equipment.  
GND  
21  
NEGATIVE  
POSITIVE  
• Do not touch electrically hot parts.  
ELECTRODE CABLE  
TO AUTOMATIC  
EQUIPMENT  
Auxiliary power for wire feeder operation is available at  
both a 14-pin MS receptacle and at terminal strips  
with screw-type connections located on the front of  
the machine. Refer to the Installation section for  
pinouts and lead designations. The two circuits are  
isolated, and each is protected by a circuit breaker.  
TO WORK  
REMOTE VOLTAGE SENSING LEAD  
5. Extend wire feeder control cable lead #21 so it can  
be connected directly to the work piece.  
a. Make a bolted connection using AWG #14 or  
larger insulated wire. Tape the bolted connec-  
tion with insulating tape.  
The following descriptions show how to connect the  
wire feeders using either the 14-pin MS receptacle or  
the terminal strip.  
b. An S-16586- X remote voltage sensing work  
lead is available for this purpose.  
c. Keep the #21 lead electrically separate from  
the work cable circuit and connection.  
d. Tape the #21 lead to work cable for ease of  
use.  
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C-4  
C-4  
ACCESSORIES  
NOTE: The connection diagram shown in Figure C.1  
shows the electrode connected for positive  
polarity. To change polarity:  
FIGURE C.2 – NA-5/-5R WIRE FEEDER  
CONNECTION TO THE IDEALARC DC-655  
14-PIN  
RECEPTACLE  
a. Set the Idealarc DC-655 POWER toggle  
switch to the OFF (0) position.  
POWER SOURCE  
CONTROL CABLE  
FOR CONTROL CABLE  
WITH 14 PIN  
MS-TYPE  
PLUG CONNECTOR  
b. Move the electrode cable to the negative (-)  
output terminal. (High inductance or low  
inductance, as needed).  
21  
TO NA-5/-5R  
INPUT CABLE PLUG  
OR  
FOR CONTROL CABLE  
WITH TERMINAL STRIP  
LEAD CONNECTORS  
CONTROL CABLE  
c. Move the work cable to the positive (+) output  
terminal.  
+
21  
-
21 41  
75 76  
77  
4
2
31 32  
d. If connecting lead #21 to the terminal strip,  
connect it to the +21 terminal (to match work  
polarity). If work polarity changes back to  
negative, lead #21 must be connected to the  
-21 terminal.  
C
B
A
32  
31  
2
4
GND  
NEGATIVE  
POSITIVE  
21  
e. Reverse the leads on the back of the ammeter  
and voltmeter in the automatic control box.  
BOLT TO CABLES FROM NA-5/-5R  
WIRE CONTACT AS'BLY  
f. If the automatic controls include a variable  
voltage board, connect its jumper lead to pin  
“L”. This will permit the inch down button to  
operate. However, the jumper also disables  
the cold starting/autostop feature of the auto-  
matic controls. Only hot starting will be avail-  
able.  
TO WORK  
REMOTE VOLTAGE SENSING LEAD  
4. Connect the wire feeder control cable ground lead  
to the frame terminal marked  
.
6. Set the DC-655 OUTPUT CONTROL switch to the  
“Remote” position and the OUTPUT TERMINALS  
switch in the “Remote” position.  
NOTE: The Idealarc DC-655 must be properly  
grounded.  
5. Extend wire feeder control cable lead #21 so it can  
be connected directly to the work piece.  
CONNECTING THE NA-5/-5R TO THE  
IDEALARC DC-655 (TERMINAL STRIP)  
a. Make a bolted connection using AWG #14 or  
larger insulated wire. Tape the bolted connec-  
tion with insulating tape.  
1. Set the Idealarc DC-655 POWER toggle switch to  
the OFF (0) position.  
b. An S-16586-X remote voltage sensing work  
lead is available for this purpose.  
2. Disconnect main AC input power to the Idealarc  
DC-655.  
c. Keep the #21 lead electrically separate from  
the work cable circuit and connection.  
3. Connect the wire feeder control cable leads to the  
Idealarc DC-655 terminal strip as shown in Figure  
C.2.  
d. Tape the #21 lead to work cable for ease of  
use.  
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C-5  
C-5  
ACCESSORIES  
6. Connect NA-5/-5R wire feeder control jumpers on  
Voltage Control Board. See NA-5/-5R Operator’s  
Manual.  
NOTE: The connection diagram shown in Figure C.2  
shows the electrode connected for positive  
polarity. To change polarity:  
a. Set the Idealarc DC-655 POWER toggle  
switch to the OFF (0) position.  
b. Move the electrode cable to the negative (-)  
output terminal. (High inductance or low  
inductance as needed).  
c. Move the work cable to the positive (+) output  
terminal.  
d. If connecting lead #21 to the terminal strip,  
connect it to the +21 terminal (to match work  
polarity). If work polarity changes back to  
negative, lead #21 must be connected to the -  
21 terminal.  
NOTE: For proper NA-5 operation, the electrode  
cables must be secured under the clamp bar  
on the left side of the NA-5 Control Box.  
7. Set the DC-655 OUTPUT CONTROL switch to the  
“Remote” position and the OUTPUT TERMINALS  
switch to the “Remote” position.  
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C-6  
C-6  
ACCESSORIES  
FIGURE C.3  
IDEALARC DC-655/LN-7 WITH K584 INPUT CABLE ASSEMBLY CONNECTION DIAGRAM  
POWER SOURCE  
LN-7 TO INPUT  
CABLE PLUG  
21  
LN-7 CONTROL  
CABLE  
+
21  
-
21 41  
75 76  
77  
4
2
31 32  
32  
31  
2
4
GND  
NEGATIVE  
POSITIVE  
21  
ELECTRODE CABLE  
TO WIRE FEED UNIT  
TO WORK  
}
REMOTE VOLTAGE SENSING LEAD  
SEMIAUTOMATIC WIRE FEEDERS  
CONNECTING THE LN-7 TO THE IDEALARC  
DC-655 (14-PIN MS RECEPTACLE)  
1. Set the POWER toggle switch to the OFF (0) posi-  
tion.  
4. Connect control cable between the DC-655 and  
the LN-7. See Figure C.3.  
2. Disconnect main AC input power to the Idealarc  
DC-655.  
5. Set the MODE switch to a CV (constant voltage)  
position at the welder.  
3. Connect the electrode cable from the control  
cable to the “+” terminal of the welder and to the  
LN-7 wire feeder. Connect the work cable to the  
“-” terminal of the welder (High inductance or low  
inductance as needed). Reverse this hookup for  
negative polarity.  
6. Adjust wire feed speed at the LN-7 and set the  
welding voltage with the output CONTROL.  
NOTE: If optional remote control is used, place the  
OUTPUT CONTROL and the OUTPUT TERMI-  
NALS switch in the “Remote” position.  
NOTE: Welding cable must be sized for the current  
and duty cycle of the application.  
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C-7  
C-7  
ACCESSORIES  
CONNECTING THE LN-7 TO THE  
IDEALARC DC-655 (TERMINAL STRIP)  
NOTE: If the work cable length is less than 25 feet  
and the connections to the work piece are  
secure, then wire feeder control cable lead  
#21 can be connected directly to the DC-  
655 terminal strip.  
1. Set the Idealarc DC-655 POWER toggle switch to  
the OFF (0) position.  
2. Disconnect main AC input power to the Idealarc  
DC 655.  
b. An S-16586-X remote voltage sensing work  
lead is available for this purpose.  
3. Connect the wire feeder control cable leads to the  
Idealarc DC-655 terminal strip as shown in Figure  
C.3.  
c. Keep the #21 lead electrically separate from  
the work cable circuit and connection.  
d. Tape the #21 lead to work cable for ease of  
use.  
4. Connect the wire feeder control cable ground lead  
to the frame terminal marked  
.
NOTE: The connection diagram shown in Figure  
C.3 shows the electrode connected for  
positive polarity. To change polarity:  
NOTE: The Idealarc DC-655 must be properly  
grounded.  
5. PERFORM THIS STEP ONLY IF THE LN-7 IS  
EQUIPPED WITH A METER KIT.  
a. Set the IDEALARC DC-655 POWER toggle  
switch to the OFF (0) position.  
Extend wire feeder control cable lead #21 so it can  
be connected directly to the work piece.  
b. Move the electrode cable to the negative (-)  
output terminal (High inductance or low induc-  
tance as needed).  
a. Make a bolted connection using AWG #14 or  
larger insulated wire. Tape the bolted connec-  
tion with insulating tape.  
c. Move the work cable to the positive (+) output  
terminal.  
d. Connect control cable lead #21 to “+21” on  
the terminal strip.  
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C-8  
C-8  
ACCESSORIES  
FIGURE C.4 - LN-8 OR LN-9 WIRE FEEDER CONNECTION TO THE IDEALARC DC-655  
POWER SOURCE  
21  
TO LN-8 OR LN-9  
INPUT CABLE PLUG  
CONTROL CABLE  
+
21  
-
21 41  
75 76  
77  
4
2
31 32  
C
B
N.E.  
}
A
32  
31  
2
4
GND  
21  
NEGATIVE  
POSITIVE  
ELECTRODE CABLE  
TO WIRE FEED UNIT  
TO WORK  
}
REMOTE VOLTAGE SENSING LEAD  
CONNECTING THE LN-8 OR LN-9 TO THE  
IDEALARC DC-655 (TERMINAL STRIP)  
6. Connect LN-9 wire feeder control jumpers on  
Voltage Control board. See LN-9 Operator’s  
Manual.  
1. Set the Idealarc DC-655 POWER toggle switch to  
the OFF (0) position.  
NOTE: The connection diagram shown in Figure C.4  
shows the electrode connected for positive  
polarity. To change polarity:  
2. Disconnect main AC input power to the Idealarc  
DC-655.  
a. Set the Idealarc DC-655 POWER toggle  
switch to the OFF (0) position.  
3. Connect the wire feeder control cable leads to the  
Idealarc DC-655 terminal strip as shown in Figure  
C.4.  
b. Move the electrode cable to the negative (-)  
output terminal (High inductance or low  
inductance as needed).  
4. Connect the wire feeder control cable ground lead  
to the frame terminal marked  
.
c. Move the work cable to the positive (+) output  
terminal.  
5. Extend wire feeder control cable lead #21 so it can  
be connected directly to the work piece.  
d. Connect control cable lead #21 to “+21” on  
the terminal strip.  
a. Make a bolted connection using AWG #14 or  
larger insulated wire. Tape the bolted connec-  
tion with insulating tape.  
7. Set the OUTPUT CONTROL switch to the  
“Remote” position and the OUTPUT TERMINALS  
switch to the “Remote” position.  
b. An S-16586- X remote voltage sensing work  
lead is available for this purpose.  
c. Keep the #21 lead electrically separate from  
the work cable circuit and connection.  
d. Tape the #21 lead to work cable for ease of  
use.  
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C-9  
C-9  
ACCESSORIES  
CONNECTING THE LN-8 OR LN-9 TO THE  
IDEALARC DC-655 (14-PIN MS RECEPTACLE)  
CONNECTING THE DH-10 TO THE  
IDEALARC DC-655 (14-PIN MS RECEPTACLE)  
1. Set the POWER toggle switch to the OFF (0) posi-  
tion.  
1. Set the POWER toggle switch to the OFF (0) posi-  
tion.  
2. Disconnect main AC input power to the Idealarc  
DC-655.  
2. Disconnect main AC input power to the Idealarc  
DC-655.  
3. Connect the electrode cable from the LN-8 or  
LN-9 to the “+” terminal of the welder. Connect  
the work cable to the “-” terminal of the welder  
(High inductance or low inductance as needed).  
Reverse this hookup for negative polarity. See  
Figure C.4.  
3. Connect the electrode cable from the DH-10 to the  
“+” terminal of the welder. Connect the work  
cable to the “-” terminal of the welder (High induc-  
tance or low inductance as needed). Reverse this  
hookup for negative polarity.  
NOTE: Welding cable must be sized for the current  
NOTE: Welding cable must be sized for the current  
and duty cycle of the application.  
and duty cycle of the application.  
4. Connect the DH-10 input cable between the 14-  
pin MS receptacle on the DC-655 and the input  
cable plug on the DH-10. See Figure C.5.  
4. Connect the control cable between the 14-pin MS  
receptacle on the DC-655 and the input cable plug  
on the LN-8 or LN-9. See Figure C.4.  
5. Set the MODE switch to a CV (constant voltage)  
position.  
5. Set the MODE switch to a CV (constant voltage)  
position.  
6. Adjust wire feed speed at the DH-10 and set the  
welding voltage with the WIRE FEEDER VOLTAGE  
CONTROL.  
6. Adjust wire feed speed at the LN-8 or LN-9 and  
set the welding voltage with the WIRE FEEDER  
VOLTAGE CONTROL.  
7. Set the DIP switches on the DH-10 for DC-655.  
See the DH-10 Operator’s Manual.  
Place the OUTPUT CONTROL switch in the “Remote”  
position and the OUTPUT TERMINALS switch in the  
“Remote” position.  
Place the OUTPUT CONTROL switch in the “Remote”  
position and the OUTPUT TERMINALS switch in the  
“Remote” position.  
FIGURE C.5 – IDEALARC DC-655 DH-10 CONNECTION  
DH-10  
WIRE  
FEEDER  
LINCOLN CV-655  
POWER SOURCE  
N.E.  
+
-
9 PIN  
AMPHENOL  
14 PIN  
AMPHENOL  
ELECTRODE CABLE  
TO WORK  
DH-10  
INPUT CABLE  
ASSEMBLY  
IDEALARC DC-655  
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Section D-1  
Section D-1  
TABLE OF CONTENTS  
-MAINTENANCE-  
Maintenance .........................................................................................................................Section D  
Safety Precautions......................................................................................................................D-2  
General Maintenance..................................................................................................................D-2  
General Component Locations...................................................................................................D-3  
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D-2  
D-2  
MAINTENANCE  
SAFETY PRECAUTIONS  
WARNING  
ELECTRIC SHOCK can kill.  
• Only qualified personnel should per-  
form this maintenance.  
Turn the input power OFF at the disconnect switch  
or fuse box before working on this equipment.  
• Do not touch electrically hot parts.  
GENERAL MAINTENANCE  
1. The fan motor has sealed bearings which require  
no service.  
2. In extremely dusty locations, dirt may restrict the  
cooling air causing the welder to run hot with pre-  
mature tripping of thermal protection. Blow ou;the  
welder with low pressure air at regular intervals to  
eliminate excessive dirt and dust build-up on inter-  
nal parts.  
3. Periodically check the welding cables. Inspect for  
any slits or punctures. Also make sure that all  
connections are tight.  
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D-3  
D-3  
MAINTENANCE  
FIGURE D.1 - GENERAL COMPONENT LOCATIONS  
1. CASE FRONT  
2. OUTPUT TERMINALS  
3. CASE SIDES  
4. CASE TOP  
5. RECONNECT PANEL (LOCATION)  
6. INPUT CONTACTOR (LOCATION)  
7. CONTROL TRANSFORMER (LOCATION)  
8. CASE BACK  
9. FAN ASSEMBLY  
10. CONTROL PANEL  
11. PC BOARDS (LOCATION)  
12. CHOKE  
13. MAIN TRANSFORMER  
14. BASE  
15. SCR RECTIFIER BRIDGE  
4
3
5
6
7
8
DC-655  
11  
10  
9
DC-655  
2
1
3
15  
12  
14  
13  
IDEALARC DC-655  
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NOTES  
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Section E-1  
Section E-1  
TABLE OF CONTENTS  
-THEORY OF OPERATION SECTION-  
Theory of Operation .............................................................................................................Section E  
General Description ....................................................................................................................E-2  
Input Line Voltage, Contactor, Reconnect,  
Fault Protection, Main and Control Transformers.......................................................................E-2  
Control Board, Firing Board, Snubber/Fan  
Board and Rectification ..............................................................................................................E-3  
Protective Devices and Shutdown Circuits ................................................................................E-4  
Thermal Protection ...............................................................................................................E-4  
Over Current Protection .......................................................................................................E-4  
Peak Current Protection.......................................................................................................E-4  
Remote Control Fault Protection..........................................................................................E-4  
Shorted Output Rectifier Fault Protection............................................................................E-4  
SCR Operation............................................................................................................................E-5  
FIGURE E.1 – DC-655 BLOCK LOGIC DIAGRAM  
CONTROL  
TRANSFORMER  
42VAC  
115VAC  
CONTROL  
BOARD  
TRANSFORMER  
FAULT PROTECTION  
CR2  
OUTPUT  
CONTROL  
ARC FORCE  
CONTROL  
OUTPUT  
CONTROL SIGNAL  
32VAC  
32VAC  
32VAC  
FIRING  
BOARD  
S
I
G
N
A
L
G
A
T
Fan  
Motor  
14-pin  
115VAC  
Amphenol Receptacle  
Fan  
Thermal  
Sensor  
E
CONTROL  
BOARD  
SNUBBER  
FAN  
BOARD  
T
S
E
MODE  
SWITCH  
T
R
115VAC  
R
I
P
M
I
N
A
L
SIGNAL  
GATE  
F
42VAC  
E
E
D
B
A
C
K
MAIN  
TRANSFORMER  
R
E
C
POSITIVE  
TERMINAL  
O
N
N
E
C
T
SHUNT  
F
E
E
D
B
A
C
LATCHING  
RESISTOR  
10VAC  
42VAC 10VAC  
CONTACTOR  
CR1  
SCR BRIDGE  
HIGH  
NEGATIVE  
TERMINAL  
CHOKE  
K
TO OPTIONAL  
METER BOARD  
LOW  
IDEALARC DC-655  
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E-2  
E-2  
THEORY OF OPERATION  
FIGURE E.2 – INPUT LINE VOLTAGE, CONTACTOR, RECONNECT,  
FAULT PROTECTION, MAIN AND CONTROL TRANSFORMERS  
CONTROL  
TRANSFORMER  
42VAC  
115VAC  
CONTROL  
BOARD  
TRANSFORMER  
FAULT PROTECTION  
CR2  
OUTPUT  
CONTROL  
ARC FORCE  
CONTROL  
OUTPUT  
CONTROL SIGNAL  
32VAC  
32VAC  
32VAC  
FIRING  
BOARD  
S
I
G
N
A
L
G
A
T
Fan  
Motor  
14-pin  
115VAC  
Amphenol Receptacle  
Fan  
Thermal  
Sensor  
E
CONTROL  
BOARD  
SNUBBER  
FAN  
BOARD  
T
S
E
MODE  
SWITCH  
T
R
115VAC  
R
I
P
M
I
N
A
L
SIGNAL  
GATE  
F
42VAC  
E
E
D
B
A
C
K
MAIN  
TRANSFORMER  
R
E
C
POSITIVE  
TERMINAL  
O
N
N
E
C
T
SHUNT  
F
E
E
D
B
A
C
K
LATCHING  
RESISTOR  
10VAC  
42VAC 10VAC  
CONTACTOR  
CR1  
SCR BRIDGE  
HIGH  
NEGATIVE  
TERMINAL  
CHOKE  
TO OPTIONAL  
METER BOARD  
LOW  
A reconnect panel allows the user to configure the  
machine for the desired input voltage. This three-  
phase AC input is applied to the primary of the main  
transformer. The transformer changes the high volt-  
age, low current input power to a lower voltage, high-  
er current output. The finishes or “neutrals” of the  
main secondary coils are connected together, and the  
six starts of the secondary windings are connected to  
the rectifier assembly.  
GENERAL DESCRIPTION  
The DC-655 is a three-phase, SCR controlled DC  
power source. It is capable of either constant current  
or constant voltage output. It is rated at 650 amps,  
100% duty cycle with outstanding arc characteristics  
for multiple welding processes.  
In addition, the main transformer also has eight isolat-  
ed secondary windings. There are three 32 VAC wind-  
ings, which provide power and “timing” to the firing  
board. The 115 VAC winding powers the fan motor  
and provides the user with up to 20 amps of 115 VAC  
auxiliary power at the receptacle or 14-pin MS type  
connector. The 42 VAC winding provides up to 10  
amps at the 14-pin MS type connector. Three other  
isolated coils are used to power the optional digital  
meter PC board. One winding is rated at 42 VAC, and  
the other two are each rated at 10 VAC.  
INPUT LINE, CONTACTOR,  
RECONNECT, FAULT PROTECTION  
AND TRANSFORMERS  
The desired three-phase input power is connected to  
the DC-655 through an input contactor located in the  
input box at the rear of the machine. Two phases of  
the input line are also connected to the control trans-  
former. The secondary of the control transformer sup-  
plies 115 VAC power to the control board transformer  
and to the input contactor through the fault protection  
relay. The control board transformer supplies 42 VAC  
to the control board.  
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.  
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E-3  
E-3  
THEORY OF OPERATION  
FIGURE E.3 – CONTROL BOARD, FIRING BOARD, SNUBBER/FAN BOARD AND RECTIFICATION  
CONTROL  
TRANSFORMER  
42VAC  
115VAC  
CONTROL  
BOARD  
TRANSFORMER  
FAULT PROTECTION  
CR2  
OUTPUT  
ARC FORCE  
CONTROL  
OUTPUT  
CONTROL SIGNAL  
32VAC  
32VAC  
32VAC  
CONTROL  
FIRING  
BOARD  
S
I
G
N
A
L
G
A
T
Fan  
Motor  
14-pin  
115VAC  
Amphenol Receptacle  
Fan  
Thermal  
Sensor  
E
CONTROL  
BOARD  
SNUBBER  
FAN  
BOARD  
T
S
E
MODE  
SWITCH  
T
R
115VAC  
R
I
P
M
I
N
A
L
SIGNAL  
GATE  
F
42VAC  
E
E
D
B
A
C
K
MAIN  
TRANSFORMER  
R
E
C
POSITIVE  
TERMINAL  
O
N
N
E
C
T
SHUNT  
F
E
E
D
B
A
C
LATCHING  
RESISTOR  
10VAC  
42VAC 10VAC  
CONTACTOR  
CR1  
SCR BRIDGE  
HIGH  
NEGATIVE  
TERMINAL  
CHOKE  
K
TO OPTIONAL  
METER BOARD  
LOW  
tion from the shunt and voltage feedback information  
from the choke and welding output terminals. This  
feedback information is processed on the control  
board. The control compares the commands of the  
mode switch, the output control potentiometer (or  
remote control device) and the arc force control with  
the feedback information and sends the appropriate  
output control signal to the firing board. In the event  
of a “fault condition,” the control board activates the  
fault relay (CR2). See Protective Devices and Shut  
Down Circuits.  
CONTROL BOARD, FIRING BOARD,  
SNUBBER/FAN, BOARD AND  
RECTIFICATION  
The “neutrals” of the welding secondary windings in  
the main transformer are connected together, and the  
six starts are connected to the six Silicon Controlled  
Rectifier (SCR) assemblies to form a six-phase output.  
This six-phase AC output from the main transformer  
secondary is rectified and controlled through the SCR  
bridge.  
A tapped output choke is connected between the neu-  
tral connection of the main transformer secondaries  
and the two negative output terminals. This large  
inductor stores energy, which provides current filtering  
for the welding output of the DC-655. Two negative  
output terminals are provided. One is connected to  
the tap lead in the choke, thus providing a lower induc-  
tance. The other utilizes the entire choke for higher  
inductance arc characteristics.  
A portion of the firing board is a three-phase circuit.  
Each phase provides two firing pulses, one for each of  
the two SCRs controlled by that phase. When a gate  
firing enable signal is received, the firing circuit sup-  
plies the proper amount of energy to the gates of the  
power SCRs. When this gate firing signal is applied at  
the correct time, through the snubber/fan board, the  
SCR will turn ON. The amount of ON time versus OFF  
time determines the output of the machine. See SCR  
Operation. At this time the latching resistor is brought  
into the machine’s output circuit. The latching resistor  
provides a pre-load for the SCR bridge.  
The snubber/fan board furnishes protection to the  
SCR bridge from the transient voltages. It also moni-  
tors the thermal sensor and activates the fan motor  
when cooling is necessary.  
The control board receives current feedback informa-  
NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.  
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E-4  
E-4  
THEORY OF OPERATION  
PROTECTIVE DEVICES AND  
SHUTDOWN CIRCUITS  
THERMAL PROTECTION  
PEAK CURRENT PROTECTION  
Two thermostats protect the DC-655 from excessive  
operating temperatures. Excessive operating temper-  
atures may be caused by a lack of cooling air or oper-  
ating the machine beyond the duty cycle and output  
rating. If excessive operating temperatures should  
occur, a thermostat will open. This condition will be  
indicated by the illumination of the yellow  
Thermostatic Protection Light located on the case  
front. The fan should continue to run, but the welding  
output will be disabled until the machine cools and the  
Thermostatic Protection Light is out.  
If the peak current exceeds 2500 amps, the welding  
output will be disabled and the control board LED 4  
shutdown light will turn on. The peak current shut-  
down circuit can be reset by turning the DC-655 input  
switch off.  
REMOTE CONTROL FAULT PROTECTION  
The remote control leads from the 14-pin receptacles  
or terminal strip are protected against voltage faults to  
the electrode circuit or auxiliary voltage supplies. If a  
fault should occur, the welding output will be disabled  
and the control board LED 4 shutdown light will turn  
on. This fault protection shutdown circuit can be reset  
by opening the feeder gun trigger or switching the DC-  
655 output terminal switch to the OFF position. On  
later production machines, LED 3 input shutdown light  
will turn on and the input contactor will open.  
OVER CURRENT PROTECTION  
If the average output current exceeds 900 amps for  
five to six seconds, the welding output will be dis-  
abled. The control board LED 4 shutdown light will  
turn on. The higher the current, the quicker the DC-  
655 will shut down. If the average current exceeds  
1200 amps, the shutdown will occur in 0.3 seconds.  
The over current shutdown circuit can be reset by  
opening the feeder gun trigger or switching the DC-  
655 output terminal switch to the OFF position.  
SHORTED OUTPUT RECTIFIER FAULT  
PROTECTION  
If a short should occur across one of the SCRs, a  
potentially hazardous AC voltage could appear across  
the welding output terminals. If such a fault should  
occur, the input contactor will open and remove the  
input power to the primary of the main transformer.  
Also, the control board LED 3 input shutdown light will  
turn on. Welding and auxiliary output will not be pre-  
sent, but the pilot light and control board power will be  
present until the power switch is turned off.  
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E-5  
E-5  
THEORY OF OPERATION  
FIGURE E.4 – SCR OPERATION  
SCR OPERATION  
A silicon controlled rectifier (SCR) is a three-terminal  
device used to control rather large currents to a load.  
An SCR acts very much like a switch. When a gate  
signal is applied to the SCR, it is turned ON and there  
is current flow from anode to cathode. In the ON state  
the SCR acts like a closed switch. When the SCR is  
turned OFF, there is no current flow from anode to  
cathode. Thus the device acts like an open switch.  
As the name suggests, the SCR is a rectifier, so it  
passes current only during positive half cycles of the  
AC supply. The positive half cycle is the portion of the  
sine wave in which the anode of the SCR is more pos-  
itive than the cathode.  
An SCR is fired by a short burst of current into the  
gate. This gate pulse must be more positive than the  
cathode voltage. Since there is a standard PN junc-  
tion between gate and cathode, the voltage between  
these terminals must be slightly greater than 0.6V .  
Once the SCR has fired, it is not necessary to contin-  
ue the flow of gate current. As long as current contin-  
ues to flow from anode to cathode, the SCR will  
remain on. When the anode to cathode current drops  
below a minimum value, called holding current, the  
SCR will shut off. This normally occurs as the AC sup-  
ply voltage passes through zero into the negative por-  
tion of the sine wave. If the SCR is turned on early in  
the positive half cycle, the conduction time is longer,  
resulting in greater SCR output. If the gate firing  
occurs later in the cycle, the conduction time is less,  
resulting in lower SCR output.  
When an AC supply voltage is applied to the SCR, the  
device spends a certain portion of the AC cycle time  
in the ON state and the remainder of the time in the  
OFF state. The amount of time spent in the ON state  
is controlled by the Gate.  
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NOTES  
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Section F-1  
Section F-1  
TABLE OF CONTENTS  
TROUBLESHOOTING & REPAIR SECTION  
Troubleshooting & Repair Section.................................................................................Section F  
How to Use Troubleshooting Guide ......................................................................................F-2  
PC Board Troubleshooting Procedures.................................................................................F-3  
Troubleshooting Guide .................................................................................................F-4–F-12  
Test Procedures  
Internal Trigger Circuit Test ...........................................................................................F-13  
Firing Board Test ...........................................................................................................F-17  
Main Transformer (T1) Voltage Test...............................................................................F-22  
Control Transformer (T2) Voltage Test...........................................................................F-27  
Control Board Transformer (T3) Test.............................................................................F-30  
Input Contactor Test......................................................................................................F-32  
Static SCR Test .............................................................................................................F-35  
Active SCR Test.............................................................................................................F-38  
Thermal Fan/Snubber Board LED Chart.......................................................................F-41  
Control Board LED Chart ..............................................................................................F-42  
Oscilloscope Waveforms  
Normal Open Circuit Voltage Waveform-Constant Current Mode................................F-43  
Normal Open Circuit Voltage Waveform-Constant Voltage MIG Maximum Output.....F-44  
Normal Open Circuit Voltage Waveform-Constant Voltage MIG Minimum Output......F-45  
Typical Output Voltage Waveform-Constant Voltage MIG............................................F-46  
Typical SCR Gate Voltage Waveform-Constant Voltage MIG.......................................F-47  
Abnormal Open Circuit Voltage Waveform-Constant Voltage MIG ..............................F-48  
Replacement Procedures  
Input Contactor (CR1) Cleaning/Replacement .............................................................F-49  
SCR Rectifier Bridge Removal and Replacement ........................................................F-51  
Main Transformer and Choke Removal and Replacement...........................................F-54  
Retest After Repair ..............................................................................................................F-57  
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F-2  
F-2  
TROUBLESHOOTING & REPAIR  
HOW TO USE TROUBLESHOOTING GUIDE  
WARNING  
Service and repair should be performed by only Lincoln Electric Factory Trained Personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician and machine  
operator and will invalidate your factory warranty. For your safety and to avoid Electrical Shock, please  
observe all safety notes and precautions detailed throughout this manual.  
This Troubleshooting Guide is provided to help  
you locate and repair possible machine malfunc-  
tions. Simply follow the three-step procedure  
listed below.  
Step 3. PERFORM COMPONENT TESTS. The  
last column, labeled “Recommended Course of  
Action” lists the most likely components that may  
have failed in your machine. It also specifies the  
appropriate test procedure to verify that the sub-  
ject component is either good or bad. If there are  
a number of possible components, check the  
components in the order listed to eliminate one  
possibility at a time until you locate the cause of  
your problem.  
Step 1. LOCATE PROBLEM (SYMPTOM). Look  
under the column labeled “PROBLEM (SYMP-  
TOMS). This column describes possible symp-  
toms that the machine may exhibit. Find the list-  
ing that best describes the symptom that the  
machine is exhibiting. Symptoms are grouped  
into three main categories: Output Problems,  
Function Problems and Welding Problems.  
All of the referenced test procedures referred to in  
the Troubleshooting Guide are described in detail  
at the end of this chapter. Refer to the  
Troubleshooting and Repair Table of Contents to  
locate each specific Test Procedure. All of the  
referred to test points, components, terminal  
strips, etc., can be found on the referenced elec-  
trical wiring diagrams and schematics. Refer to  
the Electrical Diagrams Section Table of Contents  
to locate the appropriate diagram.  
Step 2. PERFORM EXTERNAL TESTS. The  
second column, labeled “POSSIBLE AREAS OF  
MISADJUSTMENT(S)”, lists the obvious external  
possibilities that may contribute to the machine  
symptom. Perform these tests/checks in the  
order listed. In general, these tests can be con-  
ducted without removing the case wrap-around  
cover.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs  
safely, contact the Lincoln Electric Service Department for electrical troubleshooting assistance before  
you proceed. Call 1-800-833-9353.  
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F-3  
F-3  
TROUBLESHOOTING & REPAIR  
PC BOARD TROUBLESHOOTING PROCEDURES  
- Remove the PC board from the static-shielding bag  
and place it directly into the equipment. Don’t set the  
PC board on or near paper, plastic or cloth which  
could have a static charge. If the PC board can’t be  
installed immediately, put it back in the static-shield-  
ing bag.  
WARNING  
ELECTRIC SHOCK  
can kill.  
Have an electrician install and  
service this equipment. Turn the  
input power OFF at the fuse box  
before working on equipment. Do  
not touch electrically hot parts.  
- If the PC board uses protective shorting jumpers,  
don’t remove them until installation is complete.  
- If you return a PC board to The Lincoln Electric  
Company for credit, it must be in the static-shielding  
bag. This will prevent further damage and allow prop-  
er failure analysis.  
CAUTION  
Sometimes machine failures appear to be due to PC  
board failures. These problems can sometimes be  
traced to poor electrical connections. To avoid prob-  
lems when troubleshooting and replacing PC boards,  
please use the following procedure:  
4. Test the machine to determine if the failure  
symptom has been corrected by the  
replacement PC board.  
NOTE: It is desirable to have a spare (known good)  
PC board available for PC board troubleshooting.  
1. Determine to the best of your technical ability  
that the PC board is the most likely component  
causing the failure symptom.  
NOTE: Allow the machine to heat up so that all  
electrical components can reach their operating  
temperature.  
2. Check for loose connections at the PC board to  
assure that the PC board is properly connected.  
5. Remove the replacement PC board and  
substitute it with the original PC board to  
recreate the original problem.  
3. If the problem persists, replace the suspect PC  
board using standard practices to avoid static  
electrical damage and electrical shock. Read  
the warning inside the static resistant bag and  
perform the following procedures:  
a. If the original problem does not reappear by  
substituting the original board, then the PC  
board was not the problem. Continue to look  
for bad connections in the control wiring  
harness, junction blocks, and terminal strips.  
PC board can be damaged by static electricity.  
b. If the original problem is recreated by the  
substitution of the original board, then the PC  
board was the problem. Reinstall the  
replacement PC board and test the machine.  
- Remove your body’s static  
charge before opening the static-  
shielding bag. Wear an anti-static  
wrist strap. For safety, use a 1  
Meg ohm resistive cord connected  
6. Always indicate that this procedure was  
followed when warranty reports are to be  
submitted.  
to  
a
grounded part of the  
equipment frame.  
ATTENTION  
Static-Sensitive  
Devices  
Handle only at  
Static-Safe  
- If you don’t have a wrist strap,  
touch an un-painted, grounded,  
part of the equipment frame. Keep  
touching the frame to prevent  
static build-up. Be sure not to  
touch any electrically live parts at  
the same time.  
NOTE: Following this procedure and writing on the  
warranty report, “INSTALLED AND SWITCHED PC  
BOARDS TO VERIFY PROBLEM,” will help avoid  
denial of legitimate PC board warranty claims.  
Workstations  
- Tools which come in contact with the PC board must  
be either conductive, anti-static or static-dissipative.  
IDEALARC DC-655  
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F-4  
F-4  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
TROUBLESHOOTING GUIDE  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
OUTPUT PROBLEMS  
Major physical or electrical dam- 1. Contact the Lincoln Electric  
age is evident. Service Dept. 1-800-833-9353.  
The machine is dead - the input 1. The power switch (S1) is in the 1. Check the power switch (S1)  
contactor does not operate. The  
pilot light is not lit.  
ON position.  
and associated leads and con-  
nections.  
See the Wiring  
2. Check for blown or missing  
fuses in the input lines.  
Diagram.  
2. Perform the Control Trans-  
3. Check the three-phase input  
line voltage at the machine.  
The input voltage must match  
the rating plate and reconnect  
panel.  
former Test.  
The input contactor operates, but 1. Check the electrode and work 1. Perform the Internal Trigger  
no welding output. The 115 VAC  
auxiliary supply is present at the  
receptacle.  
cables for loose or faulty con-  
nections.  
Circuit Test.  
2. Perform the Firing Board Test.  
2. If the Thermal Protection Light  
is ON, the machine is overheat-  
ed. Wait for the machine to  
3. Perform the Main Transformer  
Test.  
cool and remedy the cause of 4. Perform the SCR Output  
the overheating problem. See  
the Fan/Snubber Board LED  
Chart.  
Bridge Test.  
5. The control board may be  
faulty. See Control Board LED  
Chart.  
3. Make certain either the output  
terminals switch is in the ON  
position or the external gun  
trigger circuit is functioning  
properly.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
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F-5  
F-5  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
TROUBLESHOOTING GUIDE  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
OUTPUT PROBLEMS  
The input contactor chatters.  
1. Check the three-phase input 1. Check for loose or faulty wiring  
line voltage at the machine.  
The input voltage must match  
the rating plate and reconnect  
panel configuration.  
between the input power  
switch (SW1), the fault protec-  
tion relay (CR2) and the input  
contactor.  
Diagram.  
See the Wiring  
2. The fault protection relay (CR2)  
may have defective contacts.  
Check or replace.  
3. The control board may be  
defective. See the Control  
Board LED Chart.  
4. The input contactor may be  
faulty.  
The machine is dead - the input 1. Check the three-phase input 1. Check the wiring between the  
contactor does not operate. The  
pilot light is lit.  
line voltage at the machine.  
The input voltage must match  
the rating plate and reconnect  
panel configuration.  
fault protection relay (CR2) and  
the input contactor (CR1).  
2. The fault protection relay (CR2)  
may have defective contacts.  
Check or replace.  
2. Turn the machine off and then  
back on to reset the fault pro-  
tection circuit. See the Control  
Board LED Chart.  
3. The input contactor may be  
faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
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F-6  
F-6  
TROUBLESHOOTING & REPAIR  
TROUBLESHOOTING GUIDE  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE AREAS OF  
MISADJUSTMENT(S)  
RECOMMENDED  
COURSE OF ACTION  
OUTPUT PROBLEMS  
The machine has welding output 1. Check the output control switch 1. The output control potentiome-  
but no control.  
(SW3) for proper setting.  
ter, output control switch (SW3)  
or associated wiring may be  
2. If a remote control cable is  
used, make certain the cable  
and connections are good.  
defective.  
Diagram.  
See the Wiring  
2. Perform the Firing Board Test.  
3. Perform the SCR Output  
Bridge Test.  
4. The control board may be  
faulty. See the Control Board  
LED Chart.  
The machine does not have maxi- 1. Check the three-phase input 1. The output control potentiome-  
mum output.  
lines at the DC-655. Make cer-  
tain the input voltages match  
the machine’s rating and recon-  
nect panel configuration.  
ter, output control switch (SW3)  
or associated wiring may be  
defective.  
Diagram.  
See the Wiring  
2. Put the output control switch 2. Perform the Main Transformer  
(SW3) in the “Local” control  
position. If the problem is  
resolved, the remote unit or  
wire feeder may be defective.  
Test.  
3. Perform the Firing Board Test.  
4. Perform the SCR Bridge Test.  
5. The control board may be  
faulty. See the Control Board  
LED Chart.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
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F-7  
F-7  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
TROUBLESHOOTING GUIDE  
detailed in the beginning of this manual.  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
OUTPUT PROBLEMS  
The 115 VAC receptacle is not 1. The circuit breaker may be 1. The circuit breaker may be  
working. The machine’s welding  
output is normal.  
tripped. Reset if necessary.  
defective. Check associated  
wiring. See the Wiring Diagram.  
2. Make sure the 115 VAC plug  
and “load” is in good working 2. Check for 115 VAC at terminals  
condition.  
#31 and #32 on the terminal  
strip. If 115 VAC is present at  
the terminal strip, check the  
wiring between the terminal  
stirp, the circuit breaker and the  
115 VAC receptacle. If 115 VAC  
is NOT present at the terminal  
strip, perform the Main  
Transformer Test.  
3. The 115 VAC receptacle may  
be defective.  
When not welding for a period of 1. This may be a normal condition.  
time, the machine shuts down.  
See the Idle Shut Down Timer.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
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F-8  
F-8  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
TROUBLESHOOTING GUIDE  
detailed in the beginning of this manual.  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
FUNCTION PROBLEMS  
The output control potentiometer 1. The output control switch (SW3) 1. The output control potentiome-  
does not function when the output  
control switch (SW3) is in the  
“Local” position. The DC-655  
operates normally when controlled  
remotely.  
may be defective.  
ter or associated wiring may be  
faulty. See the Wiring Diagram.  
The remote output control unit 1. The remote control unit or con- 1. The output control switch (SW3)  
does not function properly when  
the output control switch (SW3) is  
in the “Remote” position. The DC-  
655 operates normally when con-  
trolled locally from the machine’s  
output control potentiometer.  
necting cable may be defective.  
Check or replace.  
may be defective. Check or  
replace.  
Diagram.  
See the Wiring  
2. Check the remote control leads  
#75, #76 and #77 at plug P15,  
the terminal strip and the 14-pin  
MS type connector. Check for  
loose or faulty connections.  
See the Wiring Diagram.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
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F-9  
F-9  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
TROUBLESHOOTING GUIDE  
detailed in the beginning of this manual.  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
FUNCTION PROBLEMS  
The Thermal Protection Light is on 1. Check for obstructions that 1. The fan motor could be faulty.  
but the fan does not run.  
could prevent the fan from turn-  
ing.  
Check or replace.  
2. The Thermal Fan/Snubber PC  
Board may be defective. See  
the Thermal Fan/Snubber PC  
Board LED Chart.  
The fan runs continuously.  
1. Note: The fan is thermal con- 1. The Thermal Fan Thermistor  
trolled. Under normal condi-  
tions, it does not continuously  
run.  
may be faulty. See the Wiring  
Diagram.  
2. The Thermal Fan/Snubber PC  
Board may be defective. See  
the Thermal Fan/Snubber PC  
Board LED Chart.  
One or both of the optional digital 1. Check for loose plugs P13 and 1. The digital meter board may not  
meters are not lit.  
P12 at the digital meter PC  
board.  
be receiving voltages from the  
T1 transformer windings.  
Perform the Main Transformer  
Test.  
2. Check the wiring between Plug  
J13 and the associated leads at  
the main transformer. See the  
Wiring Diagram.  
3. The digital meter PC board may  
be faulty.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
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F-10  
F-10  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
TROUBLESHOOTING GUIDE  
detailed in the beginning of this manual.  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
FUNCTION PROBLEMS  
The optional digital meter is not 1. Make certain plugs P12 and 1. Check feedback leads #222,  
working properly and/or the dis-  
play is erratic.  
P13 are securely plugged into  
the digital meter PC board.  
Also make sure plug P3 is  
securely plugged into the con-  
trol board.  
#210, #201 and #202 for loose  
or faulty connections. See the  
Wiring Diagram.  
2. The optional digital meter PC  
board may be faulty.  
The analog meters are not reading 1. Make sure plug P3 is securely 1. Check feedback leads #222,  
correctly.  
plugged into the control board  
and plug J14 is securely seated  
in the plug assembly from the  
control board.  
#210, #201 and #202 for loose  
or faulty connections. See the  
Wiring Diagram.  
2. The meter(s) may be defective.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
Download from Www.Somanuals.com. All Manuals Search And Download.  
F-11  
F-11  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
detailed in the beginning of this manual.  
TROUBLESHOOTING GUIDE  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
WELDING PROBLEMS  
Poor arc characteristics in all 1. Check the three-phase input 1. Check the weld mode switch  
processes.  
line voltage at the machine.  
The input voltage must match  
the rating plate and reconnect  
panel.  
(SW2) and associated leads for  
proper operation or loose or  
faulty connections. See the  
Wiring Diagram.  
2. Check the welding cables for 2. Perform the Firing Board Test.  
loose or faulty connections.  
3. Perform the SCR Bridge Test.  
3. Make sure the proper welding  
4. Perform the Main Transformer  
procedures are being used.  
Test.  
(Wire feed speed, arc voltage  
and wire size)  
5. The control board may be  
faulty. See the Control Board  
LED Chart.  
4. Make sure the negative welding  
cable is connected to the cor-  
rect negative output terminal.  
(Low or High inductance)  
Poor arc striking with semiauto- 1. Make sure the proper welding 1. Perform the Firing Board Test.  
matic or automatic wire feeders.  
procedures are being used.  
(Wire feed speed, arc voltage  
and wire size)  
2. Perform the SCR Bridge Test.  
3. The control board may be  
faulty. See the Control Board  
LED Chart.  
2. Check the welding cables for  
loose or faulty connections.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
Download from Www.Somanuals.com. All Manuals Search And Download.  
F-12  
F-12  
TROUBLESHOOTING & REPAIR  
Observe Safety Guidelines  
TROUBLESHOOTING GUIDE  
detailed in the beginning of this manual.  
PROBLEMS  
POSSIBLE AREAS OF  
RECOMMENDED  
(SYMPTOMS)  
MISADJUSTMENT(S)  
COURSE OF ACTION  
WELDING PROBLEMS  
The arc is variable or sluggish.  
1. Check the three-phase input 1. Check the weld mode switch  
line voltage at the machine.  
The input voltage must match  
the rating plate and reconnect  
panel configuration.  
(SW2) and associated leads for  
proper operation or loose or  
faulty connections. See the  
Wiring Diagram.  
2. Make sure the machine’s set- 2. Perform the Firing Board Test.  
tings are correct for the welding  
3. Perform the SCR Bridge Test.  
process.  
4. Perform the Main Transformer  
3. Check the welding cables for  
Test.  
loose or faulty connections.  
Also make sure cables are sized 5. The control board may be  
correctly for the welding cur-  
rent.  
faulty. See the Control Board  
LED Chart.  
4. See CV Mode Current  
Limiting.  
The Arc Force Control (R4) has no 1. The Arc Force Control is active 1. Check the Arc Force Control  
effect on the arc.  
only in the CC Stick mode.  
potentiometer (R4) for the cor-  
rect resistance and proper  
operation. Normal resistance is  
10,000 ohms.  
2. The effect of the Arc Force  
Control will be less noticeable  
at high welding currents. Weld  
at low currents (less than 150 2. Check the continuity of leads  
amps) and check the Arc Force  
control function.  
#321, #322 and #328 from the  
Arc Force Control to the control  
board. See the Wiring Diagram.  
3. The control board may be  
faulty. Replace.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-  
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call  
1-800-833-9353.  
IDEALARC DC-655  
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F-13  
F-13  
TROUBLESHOOTING & REPAIR  
INTERNAL TRIGGER CIRCUIT TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained person-  
nel. Unauthorized repairs performed on this equipment may result in danger to the tech-  
nician or machine operator and will invalidate your factory warranty. For your safety and  
to avoid electrical shock, please observe all safety notes and precautions detailed  
throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353  
(WELD).  
TEST DESCRIPTION  
This test will help determine if the wiring and connections are good from the 14-pin  
receptacle and terminal strip through the P15 and P16 connectors and thermostats to the  
firing board. The technician will also be able to determine if the 42 VAC trigger supply  
voltage is present.  
MATERIALS NEEDED  
Ohmmeter (Multimeter)  
DC-655 Wiring Diagram  
Simplified Trigger Diagram  
IDEALARC DC-655  
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F-14  
F-14  
TROUBLESHOOTING & REPAIR  
INTERNAL TRIGGER CIRCUIT TEST (continued)  
FIGURE F.1 – FIRING BOARD TRIGGER CIRCUIT TEST POINTS AND LEDS  
LED7  
LED8  
LED9  
J5  
8
7
6
5
4
3
2
1
16  
15  
14  
13  
12  
11  
10  
9
LED2  
LED1  
G2699-[ ]  
J6  
LED10  
LED4  
LED6  
LED3  
LED5  
J7  
J4  
FIRING BOARD  
2. If LED 10 does not light when the trigger cir-  
cuit is activated, proceed with the following  
voltage and continuity checks.  
WARNING  
ELECTRIC SHOCK can kill.  
3. Check the 10 Amp circuit breaker. It is the  
one closest to the 115V duplex receptacle.  
Reset if tripped.  
• Do not touch electrically hot  
parts.  
TEST PROCEDURE  
1. With the correct input power applied to the  
DC-655 and the trigger circuit activated,  
LED 10 on the firing board should be lit.  
See Figure F.1. If LED 10 lights when the  
trigger is activated, the wiring and circuitry  
to the firing board is good. Perform the  
Firing Board Test and see the Control  
Board LED Chart. See the Simplified  
Trigger Diagram.  
NOTE: LED 10 should not be lit if the trigger  
circuit is not activated.  
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F-15  
F-15  
TROUBLESHOOTING & REPAIR  
FIGURE F.2 – TERMINAL STRIP AND 14-PIN RECEPTACLE  
K=42  
J=31  
A=32  
14 PIN MS RECEPTACLE  
B=GND  
L
I=41  
N
C=2  
H=21  
G=75  
D=4  
E=77  
F=76  
M
POSITIVE  
OUTPUT  
TERMINAL  
LOW INDUCTANCE  
HIGH INDUCTANCE  
NEGATIVE OUTPUT  
NEGATIVE OUTPUT  
TERMINAL  
TERMINAL STRIP  
COVER PANEL  
TERMINAL  
+21 -21 41  
4
2
31 32  
75 76 77  
TERMINAL STRIP  
4. Check for the presence of 42 VAC at the ter-  
minal strip ( #2 to #41). See the Simplified  
Trigger Diagram.  
8. Check continuity (zero ohms) from pin “D”  
(lead #4) at the 14-pin receptacle to the out-  
put terminal switch and also to plug J5-pin  
9 at the firing board. See the Simplified  
Trigger Diagram and Figures F.1 and F.2. If  
a resistance of any value is indicated, check  
the associated wires and plugs.  
5. If 42 VAC is not present at the terminal strip,  
check the circuit breaker and leads #42A  
and #41 at the P15 connector. See the  
Simplified Trigger Diagram. Also perform  
the Main Transformer Test.  
6. Remove the main input supply power to the  
DC-655 machine.  
7. Check continuity (zero ohms) from lead  
#42A ( plug P15 pin-13) to lead #2 at the 14-  
pin receptacle pin “C”. Also check continu-  
ity to the output terminal switch. See the  
Simplified Trigger Diagram. If a resistance  
of any value is indicated, check the associ-  
ated wires and plugs.  
IDEALARC DC-655  
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F-16  
F-16  
TROUBLESHOOTING & REPAIR  
9. Check continuity (zero ohms) from lead #41  
(plug P15 pin-10) to plug J5-pin 1 at the fir-  
ing board. See the Simplified Trigger  
Diagram and Figure F.1. If a resistance of  
any value is indicated, check the associat-  
ed wires, plugs and thermostats.  
FIGURE F.3 – SIMPLIFIED TRIGGER DIAGRAM  
10AMP  
CIRCUIT  
BREAKER  
TO #42 AT MAIN  
TRANSFORMER  
42A  
FIRING BOARD  
TERMINAL  
STRIP  
P15  
13  
P16  
11J5  
10J5  
#309  
14-PIN  
RECEPTACLE  
TO  
CONTROL  
BOARD  
OUTPUT  
TERMINAL  
SWITCH  
C
2
4
2
5
2
#
5
6
LED10  
#310  
LATCHING  
RESISTOR  
ENABLE  
D
4
9
#4  
#4  
9J5  
1J5  
11  
10  
#41  
41  
#273  
#41  
FIRING  
CIRCUIT  
ENABLE  
N.C.  
CHOKE LEAD  
THERMOSTAT  
N.C.  
SECONDARY  
THERMOSTAT  
TO #41 AT MAIN  
TRANSFORMER  
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F-17  
F-17  
TROUBLESHOOTING & REPAIR  
FIRING BOARD TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained person-  
nel. Unauthorized repairs performed on this equipment may result in danger to the tech-  
nician or machine operator and will invalidate your factory warranty. For your safety and  
to avoid electrical shock, please observe all safety notes and precautions detailed  
throughout this manual.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353  
(WELD).  
TEST DESCRIPTION  
This test will help determine whether or not the firing board is receiving the correct volt-  
ages and signals. The LEDs (Light Emitting Diodes) will help determine if the firing board  
is generating gate signals for the main SCRs.  
MATERIALS NEEDED  
Volt/ohmmeter (Multimeter)  
DC-655 wiring diagram and firing board schematic drawing  
IDEALARC DC-655  
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F-18  
F-18  
TROUBLESHOOTING & REPAIR  
FIRING BOARD TEST (continued)  
FIGURE F.4 – FIRING BOARD TRIGGER CIRCUIT TEST POINTS AND LEDs  
LED7  
LED8  
LED9  
J5  
(205) 8  
16 (204)  
15 (203)  
14  
(206) 7  
(207) 6  
(208) 5  
13 (231)  
12 (215)  
11  
4
3
2
1
LED2  
LED1  
G2699-[ ]  
10  
9
J6  
J7  
LED10  
LED4  
LED6  
LED3  
LED5  
J4  
FIRING BOARD  
TEST PROCEDURE  
1. Disconnect the AC input power to the DC-  
655 machine.  
WARNING  
ELECTRIC SHOCK can kill.  
2. Locate the firing board on the left side of  
the control box.  
• Do not touch electrically hot  
parts.  
3. Perform a visual inspection on the firing  
board to see if there are any loose or faulty  
connections or physical damage.  
4. Connect the correct AC input power to the  
DC-655.  
5. Turn the power switch (SW1) to the ON  
position.  
6. LEDs 7, 8 and 9 should be lit and equally  
bright. See Figure F.4 to locate the LEDs.  
Use Table F.1 to check operation of LEDs 7,  
8, and 9. The three LEDs should be of  
equal intensity.  
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F-19  
F-19  
TROUBLESHOOTING & REPAIR  
FIRING BOARD TEST (continued)  
TABLE F.1 - LED 7, 8, 9 AND 10  
IF  
THEN  
LED 7 is ON  
32 VAC power is being supplied to the  
firing board from leads #203 and  
#204 connected to the phase angle  
winding in the Main Transformer.  
Normal is 32 VAC.  
LED 7 is not lit or is dimmer than  
the other LEDs  
The proper AC voltage may not be  
reaching the firing board. Check for  
loose or faulty connections. Perform  
the Main Transformer Test.  
LED 8 is ON  
32 VAC power is being supplied to the  
firing board from leads #205 and #206  
connected to the phase angle winding in  
the Main Transformer.  
LED 8 is not lit or is dimmer than  
the other LEDs  
The proper AC power may not be  
reaching the firing board. Check for  
loose or faulty connections. Perform  
the Main Transformer Test.  
LED 9 is ON  
32 VAC power is being supplied to  
the firing board from leads #207 and  
#208 connected to the phase angle  
winding in the Main Transformer.  
LED 9 is not lit or is dimmer than  
the other LEDs  
The proper AC power may not be  
reaching the firing board. Check for  
loose or faulty connections. Perform  
the Main Transformer Test.  
LED 10 is ON  
This indicates the trigger circuit is  
activated at the 14-pin receptacle or  
the terminal strip or that the Output  
Terminal Switch (SW5) is closed.  
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F-20  
F-20  
TROUBLESHOOTING & REPAIR  
FIGURE F.5 – 14-PIN RECEPTACLE  
K=42  
J=31  
A=32  
B=GND  
I=41  
L
N
C=2  
H=21  
G=75  
D=4  
E=77  
F=76  
M
7. Connect a jumper wire from pin C (lead #2)  
to pin D (lead #4) at the 14-pin receptacle.  
See Figure F.5. (Or put the Output Terminal  
Switch in the ON position.) This should ini-  
tiate machine output at the welding termi-  
nals. LED 10 on the firing board should  
now be on. See Table F.1. If LED 10 does  
not glow when leads #2 and #4 are con-  
nected together, perform the Internal  
Trigger Test. The firing board may be  
faulty.  
11. Rotate the Output Control Potentiometer  
(R1). As the pot is turned clockwise, LEDs  
1 through 6 should get brighter. As the pot  
is turned counter-clockwise, the LEDs  
should get dimmer.  
If the LEDs glow and change in brightness  
equally as the pot is turned, and the prob-  
lem continues, the SCR bridge may be  
faulty. Perform the SCR Output Bridge  
Test.  
If one or two lights stay bright or dim and  
the others change, this could indicate an  
open or shorted gate lead or faulty snubber  
board. Perform the SCR Output Bridge  
Test. If the Output Bridge and associated  
gate leads are OK, the firing board may be  
faulty.  
8. Locate LEDs 1 to 6 on the firing board. See  
Figure F.4. Each LED should glow with  
equal brightness.  
NOTE: LEDs 1 through 6 indicate that the  
SCR gate firing signals are being generated  
by the firing board.  
9. Set the Output Control Switch (SW3) in the  
“Output Control at DC-655” (local) position.  
If all of LEDs 1 through 6 do not glow or do  
not change in brightness equally as the  
output control is rotated, go to step 12.  
10. Set the Mode Switch (SW2) in a constant  
voltage (CV) position.  
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F-21  
F-21  
TROUBLESHOOTING & REPAIR  
12. Test for 9.5 VDC to 11.0 VDC between  
leads #231 and #215 on the firing board.  
13. Test for approximately 5.5 VDC between  
leads #231 and #215 on the firing board.  
See Figure F.4.  
Make sure the Mode Switch (SW2) is in a  
constant voltage (CV) position.  
Put the Mode Switch (SW2) in the constant  
current (CC) position.  
Locate plug J5 on the firing board. Locate  
leads #231 (pin-13) and #215 (pin-12). See  
Figure F.4.  
Rotate the Output Control (R1) clockwise  
and counter-clockwise. The DC voltage  
between leads #231 and #215 should be  
constant at approximately 5.5 VDC. This  
voltage should not vary when the output  
control is turned.  
Connect a jumper wire from pin C (lead #2)  
to pin D (lead #4) at the 14-pin receptacle.  
(Or put the Output Terminal Switch in the  
ON position.) This should initiate machine  
output at the welding terminals.  
Rotate the Output Control (R1) clockwise  
and counter-clockwise. The DC voltage  
between leads #231 and #215 should vary  
from 9.5 VDC to 11.0 VDC as the control is  
turned from minimum to maximum. If the  
voltage varies and LEDs 1 through 6 do  
NOT vary in brightness, the firing board  
may be faulty.  
If the voltage does NOT vary, the control  
board, control potentiometer or associated  
leads may be faulty. See the Wiring  
Diagram.  
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F-22  
F-22  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER (T1) VOLTAGE TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
This test will determine if the correct voltages are being applied to the primary windings of  
the main transformer. The secondary windings, the auxiliary windings and the phase angle  
windings will also be checked.  
MATERIALS NEEDED  
Volt/ohmmeter (Multimeter)  
DC-655 Wiring Diagram  
IDEALARC DC-655  
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F-23  
F-23  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER (T1) VOLTAGE TEST (continued)  
FIGURE F.6 – INPUT CONTACTOR AND PRIMARY LEADS  
TEST PROCEDURE  
1. Disconnect the main input power from the  
DC-655.  
6. Make sure the input contactor (CR1) ener-  
gizes.  
2. Inspect the input contactor, reconnect  
panel and primary leads to the main trans-  
former for loose or faulty connections. See  
Figure F.6. Remove the case sides.  
7. Test with an AC voltmeter for the proper  
main AC input voltages applied to the line  
side of the input contactor (CR1). See the  
Wiring Diagram. If the correct voltages are  
not present at the line side of the input  
contactor, check the input fuses and leads.  
3. Confirm that the reconnect panel is config-  
ured correctly for the three-phase AC input  
power supplied to the DC-655. See the  
connection diagram located on the inside  
of the input box assembly.  
a. L1 to L2  
b. L2 to L3  
c. L1 to L3  
4. Connect the correct AC three-phase input  
power to the DC-655 machine.  
8. Test with an AC voltmeter for the proper  
AC input voltages at the output side of the  
input contactor (CR1). See the Wiring  
Diagram. If the correct voltages are not  
present, perform the Input Contactor  
Test.  
WARNING  
ELECTRIC SHOCK can kill.  
• Do not touch electrically hot  
parts.  
a. T1 to T2  
b. T2 to T3  
c. T1 to T3  
5. Turn the power switch (SW1) to the ON  
position.  
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F-24  
F-24  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER (T1) VOLTAGE TEST (continued)  
FIGURE F.7 - MAIN TRANSFORMER SECONDARY LEADS TO  
COMMON BUS VOLTAGE CHECK  
COMMON  
BUS  
CHOKE  
SECONDARY  
LEADS (6)  
MAIN  
TRANSFORMER  
9. Test with an AC voltmeter for approximately  
NOTE: The secondary voltages will vary if the  
input line voltages vary. If any one or more of the  
voltage checks are incorrect, check for loose or  
faulty connections. See the Wiring Diagram. If  
the leads and connections are OK, the main  
transformer may be faulty.  
55 VAC from each of the six main trans-  
former secondary leads to the common bus  
connected to the output choke. See Figure  
F.7.  
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F-25  
F-25  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER (T1) VOLTAGE TEST (continued)  
FIGURE F.8 - TERMINAL STRIP  
14 PIN MS RECEPTACLE  
POSITIVE  
OUTPUT  
TERMINAL  
HIGH INDUCTANCE  
NEGATIVE OUTPUT  
TERMINAL  
LOW INDUCTANCE  
NEGATIVE OUTPUT  
TERMINAL  
TERMINAL STRIP  
COVER PANEL  
+21 -21 41  
4
2
31 32  
75 76 77  
TERMINAL STRIP  
10. Test for 115 VAC between leads #31 and  
#32 on the terminal strip. The terminal strip  
can be accessed by removing the small  
panel at the lower portion of the case front.  
See Figure F.8. 115 VAC AC should also be  
present at the 115 VAC receptacle. If the  
correct voltage is not present, make sure  
the 20 amp circuit breaker is not tripped or  
faulty. Also check the wiring between the  
main transformer, the terminal strip, the cir-  
cuit breaker and the receptacle. See the  
Wiring Diagram.  
12. Test for 42 VAC between leads #41 and #2  
on the terminal strip. The terminal strip can  
be accessed by removing the small panel  
at the lower portion of the case front. See  
Figure F.8. If the correct voltage is not pre-  
sent, make sure the 10 amp circuit breaker  
is not tripped or faulty. Also check the  
wiring between the main transformer, the  
terminal strip, and the circuit breaker. See  
the Wiring Diagram.  
13. Remove the AC input power to the DC-  
655. Remove the screws from the control  
box cover and carefully lower the cover.  
11. If 115 VAC is NOT present and the wiring  
and circuit breaker are good, the main  
transformer may be defective.  
14. Locate the firing board on the left side of  
the control box.  
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F-26  
F-26  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER (T1) VOLTAGE TEST (continued)  
FIGURE F.9 - FIRING BOARD PLUG J5 PINS  
LED7  
LED8  
LED9  
J5  
(205) 8  
16 (204)  
15 (203)  
14  
(206) 7  
(207) 6  
(208) 5  
13 (231)  
12 (215)  
11  
4
3
2
1
LED2  
LED1  
G2699-[ ]  
10  
9
J6  
J7  
LED10  
LED4  
LED6  
LED3  
LED5  
J4  
FIRING BOARD  
15. Locate plug J5 on the firing board. See  
Figure F.9.  
17. Locate plug J13 on the optional digital  
meter board. If a digital meter board is not  
in place, plug J13 will not be used but will  
be present in the harness. Check the fol-  
lowing voltages at the appropriate leads  
and pin locations.  
WARNING  
ELECTRIC SHOCK can kill.  
10 VAC Plug J13 pin-1 (lead #331) to pin-2  
(lead #332)  
• Do not touch electrically hot  
parts.  
10 VAC Plug J13 pin-4 (lead #333) to pin-5  
(lead #334)  
42 VAC Plug J13 pin-3 (lead #335) to pin-6  
(lead #336)  
18. If the correct primary voltages are applied  
to the main transformer and any of the sec-  
ondary voltages are missing or not correct,  
the transformer may be faulty.  
16. Turn on the DC-655 and check for approx-  
imately 32 VAC at the following leads and  
pins at plug J5. These are the phase angle  
winding voltages. See Fig. F.9.  
NOTE: Always check the wiring between  
the transformer windings and the test  
points before replacing the transformer.  
Plug J5 pin-15 (lead #203) to pin-16 (lead  
#204)  
Plug J5 pin-8 (lead #205) to pin-7 (lead  
#206)  
Plug J5 pin-6 (lead #207) to pin-5 (lead  
#208)  
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F-27  
F-27  
TROUBLESHOOTING & REPAIR  
CONTROL TRANSFORMER (T2) TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
This procedure will determine if the correct voltage is being applied to the primary of the con-  
trol transformer and also if the correct voltage is being induced upon the secondary winding.  
MATERIALS NEEDED  
Volt/ohmmeter (Multimeter)  
DC-655 Wiring Diagram  
IDEALARC DC-655  
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F-28  
F-28  
TROUBLESHOOTING & REPAIR  
CONTROL TRANSFORMER (T2) TEST (continued)  
FIGURE F.10 – CONTROL TRANSFORMER  
211  
TEST PROCEDURE  
1. Disconnect the main AC input voltage to the  
4. Locate the control transformer primary leads  
(H1, H2, H3, etc.). See the Wiring Diagram.  
DC-655.  
2. Remove the case top and sides.  
NOTE: Unused leads should be insulated and  
taped. Inspect for broken or incorrect connec-  
tions.  
3. Locate the control transformer (T2) on the  
left side of the input box (facing the back of  
the machine). See Figure F.10.  
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F-29  
F-29  
TROUBLESHOOTING & REPAIR  
CONTROL TRANSFORMER (T2) TEST (continued)  
5. Locate the control transformer secondary  
leads. See Figure F.10. Lead X1 is con-  
nected to the coil terminal on the CR1 input  
contactor. Lead X2 is spliced into lead  
#211, which is then connected to the input  
power switch (SW1).  
7. If approximately 115 VAC is present at leads  
X1 to X2, the control transformer is function-  
ing properly.  
8. If approximately 115 VAC is NOT present at  
leads X1 to X2, make certain the correct  
input voltage is being applied to the primary  
winding of the control transformer and that  
the correct primary leads (H1, H2, H3, etc.)  
are being used. See the connection infor-  
mation diagram on the input access door.  
WARNING  
HIGH VOLTAGE is present at  
the input leads.  
9. If the correct voltage is being applied to the  
primary of the control transformer and the  
secondary voltage is incorrect or not pre-  
sent, the control transformer may be defec-  
tive.  
6. Apply the correct three-phase input power  
to the DC-655 and check for 115 VAC at  
leads X1 to X2.  
NOTE: The DC-655 does not have to be ON  
to perform this test. If the main AC input  
supply voltage varies, the control trans-  
former secondary voltage will vary by the  
same percentage.  
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F-30  
F-30  
TROUBLESHOOTING & REPAIR  
CONTROL BOARD TRANSFORMER (T3) TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
This test will determine if the correct voltage is being applied to the primary winding of the  
control board transformer (T3) and also if the correct voltage is being induced upon the sec-  
ondary winding.  
MATERIALS NEEDED  
Volt/ohmmeter (Multimeter)  
DC-655 Wiring Diagram  
IDEALARC DC-655  
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F-31  
F-31  
TROUBLESHOOTING & REPAIR  
CONTROL BOARD TRANSFORMER (T3) TEST (continued)  
FIGURE F.11 – CONTROL BOARD TRANSFORMER (T3) LEADS  
CONTROL BOARD  
TRANSFORMER  
(T3)  
CONTROL  
BOX  
SECONDARY  
LEADS #281  
AND #282  
PRIMARY LEADS  
AND #256  
#255  
TEST PROCEDURE  
1. Disconnect the main AC input power to the  
DC-655 machine.  
5. Apply the correct three-phase input power  
to the DC-655 and turn the power switch  
(SW1) to the ON position.  
2. Remove the case top and sides.  
6. Carefully check for 42 VAC at the secondary  
leads (#281 to #282). If 42 VAC is present,  
the control board transformer (T3) is good. If  
42 VAC is missing or low, proceed to the  
next step.  
3. Locate the control board transformer (T3)  
mounted on the rear of the control box. See  
Figure F.11.  
4. Locate the transformer (T3) primary leads  
(#255 and $256). See Figure F.11 and the  
Wiring Diagram. Also locate the secondary  
leads (#281 and #282).  
7. Carefully check for 115 VAC at the primary  
leads (#255 and #256). If the 115 VAC is  
present but the secondary voltage (42 VAC)  
is missing or low, the T3 transformer may be  
faulty. Replace.  
WARNING  
8. If the 115 VAC is NOT present at the prima-  
ry leads, check the associated switch (SW1)  
and wiring. See the Wiring Diagram.  
ELECTRIC SHOCK can kill.  
• Do not touch electrically hot parts.  
9. Perform the Control Transformer (T2) Test.  
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F-32  
F-32  
TROUBLESHOOTING & REPAIR  
INPUT CONTACTOR TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
This test will help determine if the input contactor is receiving the correct coil voltage and if  
the contacts are functioning correctly.  
MATERIALS NEEDED  
Volt/ohmmeter (Multimeter)  
3/8” Nut driver  
DC-655 Wiring Diagram  
External 120 VAC supply  
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F-33  
F-33  
TROUBLESHOOTING & REPAIR  
INPUT CONTACTOR TEST (continued)  
FIGURE F.12 – INPUT CONTACTOR CONNECTIONS  
X1, #256  
#255A  
TEST PROCEDURE  
1. Disconnect the main input supply power to  
the machine.  
5. Apply the correct three-phase input power  
to the DC-655 and turn the power switch  
(SW1) to the ON position.  
2. With the 3/8” nut driver, remove the case top  
and input access cover.  
6. Check for 120 VAC at the contactor coil  
leads.  
3. Locate the three leads connected to the  
input contactor coil (X1/#256 and #255A).  
See Figure F.12.  
7. If the 120 VAC is NOT present, with the input  
power switch (SW1) on, check the switch  
and associated circuitry. See the Wiring  
Diagram. Also see the Control Board LED  
Chart. Relay CR2 may be faulty. See the  
Wiring Diagram. Perform the Control  
Transformer (T2) Test.  
4. Connect an AC voltmeter to the leads.  
WARNING  
ELECTRIC SHOCK can kill.  
8. If the 120 VAC IS present and the contactor  
does NOT activate, the input contactor is  
faulty. Replace the input contactor.  
• Do not touch electrically hot parts.  
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F-34  
F-34  
TROUBLESHOOTING & REPAIR  
INPUT CONTACTOR TEST (continued)  
FIGURE F.13 – INPUT CONTACTOR TEST CONNECTIONS  
X1, #256  
#256  
#255A  
#255A  
TEST FOR CONTACT CONTINUITY  
1. Disconnect the main input supply power to  
the DC-655 machine.  
4. With the contactor activated, check the  
continuity across the contacts. (Zero ohms  
or very low resistance is normal.) See  
Figure F.13. If the resistance is high, the  
input contactor is faulty. Replace the input  
contactor.  
2. Locate, label and remove the three leads  
connected to the input contactor coil  
(X1/#256 and #255A). See Figure F.13.  
5. When the contactor is NOT activated, the  
resistance should be infinite or very high  
across the contacts. If the resistance is  
low, the input contactor is faulty. Replace  
the input contactor.  
WARNING  
ELECTRIC SHOCK can kill.  
• Do not touch electrically hot  
parts.  
3. Using the external 120 VAC supply, apply  
120 VAC to the terminals of the input con-  
tactor coil. If the contactor does NOT acti-  
vate, the input contactor is faulty.  
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F-35  
F-35  
TROUBLESHOOTING & REPAIR  
STATIC SCR TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
The test is used to quickly determine if an SCR is shorted or “leaky.” See the Oscilloscope  
Waveform Section in this manual for normal and abnormal SCR waveforms.  
MATERIALS NEEDED  
Analog ohmmeter (Multimeter)  
DC-655 Wiring Diagram  
IDEALARC DC-655  
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F-36  
F-36  
TROUBLESHOOTING & REPAIR  
STATIC SCR TEST (continued)  
FIGURE F.14 – THERMAL FAN/SNUBBER BOARD AND FIRING BOARD PLUG LOCATIONS  
THERMAL FAN / SNUBBER L10124-[ ]  
LED2  
LED6  
LED5  
LED1  
LED4  
LED3  
PLUG J9  
LED7  
LED8  
LED9  
J5  
LED2  
LED1  
G2699-[ ]  
J6  
LED10  
LED4  
LED6  
LED3  
LED5  
J7  
J4  
FIRING BOARD  
TEST PROCEDURE  
1. Disconnect the main AC input power to the  
DC-655 machine.  
4. Test for high or infinite resistance from the  
anode to the cathode of SCR1. See Figure  
F.15. Use an analog ohmmeter (multimeter).  
2. Locate and disconnect plug J9 from the  
thermal fan/snubber board and plug J5 from  
the firing board. See Figure F.14.  
5. Test for high or infinite resistance from the  
cathode to the anode of SCR1 by reversing  
the meter leads. See Figure F.15.  
3. Remove the red insulating paint from the  
heat sink test points. See Figure F.15. DO  
NOT DISASSEMBLE THE HEAT SINKS.  
IDEALARC DC-655  
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F-37  
F-37  
TROUBLESHOOTING & REPAIR  
STATIC SCR TEST (continued)  
FIGURE F.15 – HEAT SINK TEST POINTS  
ANODE  
CATHODE  
REMOVE  
INSULATING  
PAINT  
6. If a high or infinite resistance is indicated for  
both steps #4 and #5, SCR1 is not shorted.  
8. Replace plug J9 into the thermal fan/snub-  
ber board and plug J5 into the firing board.  
7. If a low resistance is indicated in either steps  
#4 or #5, there is a shorted SCR in the out-  
put rectifier bridge. Repeat steps #4 and #5  
for each of the six SCRs. It may be neces-  
sary to disconnect the transformer sec-  
ondary leads from the rectifier assembly to  
isolate the defective SCR(s). See the Wiring  
Diagram.  
NOTE: To further check the SCRs’ functions use  
an SCR tester and proceed to the Active SCR  
Test.  
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F-38  
F-38  
TROUBLESHOOTING & REPAIR  
ACTIVE SCR TEST  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
TEST DESCRIPTION  
The Active SCR Test will determine if the device is able to be gated ON and conduct current  
from anode to cathode.  
MATERIALS NEEDED  
An SCR Tester as specified in this procedure  
DC-655 Wiring Diagram  
IDEALARC DC-655  
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F-39  
F-39  
TROUBLESHOOTING & REPAIR  
ACTIVE SCR TEST (continued)  
FIGURE F.16 – THERMAL FAN/SNUBBER BOARD AND FIRING BOARD PLUG LOCATIONS  
THERMAL FAN / SNUBBER L10124-[ ]  
LED2  
LED6  
LED5  
LED1  
LED4  
LED3  
PLUG J20  
PLUG J9  
LED7  
LED8  
LED9  
J5  
LED2  
LED1  
G2699-[ ]  
J6  
LED10  
LED4  
LED6  
LED3  
LED5  
J7  
J4  
FIRING BOARD  
TEST PROCEDURE  
1. Disconnect the main AC input power to the  
machine.  
3. Remove the red insulating paint from the  
heat sink test points. See Figure F.17. DO  
NOT DISASSEMBLE THE HEAT SINKS.  
2. Locate and disconnect plug J9 from the  
thermal fan/snubber board and plug J5 from  
the firing board. See Figure F.16.  
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F-40  
F-40  
TROUBLESHOOTING & REPAIR  
ACTIVE SCR TEST (continued)  
FIGURE F.17 – HEAT SINK TEST POINTS  
ANODE  
CATHODE  
SW1  
R2  
+
R1  
V
SW2  
A
R1 = 4 ohms/10 watts  
R2 = 3 ohms/10 watts  
6 VOLT  
LANTERN  
BATTERY  
G
SCR  
UNDER  
TEST  
C
To test SCRs construct the circuit outlined above. Resistor values are plus or minus  
ten precent. The voltmeter scale should be low, approximately 0-5 or 0-10 volts DC.  
4. Construct the circuit shown in Figure F.17.  
One 6-volt lantern battery can be used. Set  
the voltmeter scale low, at approximately 0-  
5 volts or 0-10 volts.  
b. If the voltage is 3-6 volts only when the  
switch is closed or there is no voltage  
when the switch is closed, the SCR is  
defective.  
a. Test the voltage level of the battery.  
Short leads (A) and (C). Close switch  
SW-1. Battery voltage should be 4.5  
volts or higher. If lower, replace the bat-  
tery.  
NOTE: Be sure the battery is functioning  
properly. A low battery can affect the  
results of the test. Repeat the battery  
test procedure in Step 4 if needed.  
10. Open switch SW-1.  
5. Connect the Tester to SCR 1 as shown in  
Figure F.17.  
11. Reconnect the Tester leads. See Figure  
F.17.  
a. Connect Tester lead (A) to the anode.  
b. Connect Tester lead (C) to the cathode.  
c. Connect Tester lead (G) to the gate.  
a. Connect Tester lead (A) to the cathode.  
b. Connect Tester lead (C) to the anode.  
c. Disconnect Test lead (G) from the gate.  
6. Close switch SW-1.  
12. Close switch SW-1.  
NOTE: Switch SW-2 should be open.  
13. Read the meter for zero voltage.  
a. If the voltage is zero, the SCR is func-  
tioning.  
7. Read the meter for zero voltage.  
a. If the voltage reading is higher than zero,  
the SCR is shorted.  
b. If the voltage is higher than zero, the  
SCR is shorted.  
8. Close or keep closed switch SW-1.  
9. Close switch SW-2 for 2 seconds and  
release and read the meter.  
14. Perform the Active Test Procedure outlined  
in Steps 5-13 for SCRs 2-6.  
a. If the voltage is 3-6 volts while the  
switch is closed and after the switch is  
open, the SCR is functioning.  
15. Replace all SCR assemblies that do not  
pass the above tests.  
16. Plug J9 onto the thermal fan/snubber board  
and plug J5 into the firing board.  
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F-41  
F-41  
TROUBLESHOOTING & REPAIR  
THERMAL FAN/SNUBBER BOARD LED CHART  
LED #  
LED FUNCTIONS AND INDICATIONS  
(Machine is ON)  
1
2
3
Indicates fan should be running.  
Indicates welding current is greater than 200 amps.  
Indicates fan should be running due to heating of main  
SCRs.  
4
Indicates an open thermal fan thermistor or an open con-  
nection between the thermistor and the thermal fan/snub-  
ber board. See the Wiring Diagram (leads #319 and  
#316).  
5
6
Indicates a thermostat (choke or secondary) has opened.  
The thermal protection light should also be illuminated.  
Indicates the fan motor should be running. LED 6 should  
be illuminated and the fan running when any  
of the following LEDs are lit: LED 2, LED 3, LED 4, or  
LED 5.  
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F-42  
F-42  
TROUBLESHOOTING & REPAIR  
CONTROL BOARD LED CHART  
LED #  
LED FUNCTIONS AND INDICATIONS  
(Machine is ON)  
1
Indicates that the mode switch (SW2) is in the CC mode.  
When LED 1 is on, LED 6 should also be  
illuminated.  
2
3
Indicates that feedback voltage is present. This informa-  
tion is used when the machine is in a CV mode. This LED  
should get brighter as the output voltage is increased.  
Indicates an input shutdown. The normally closed relay  
CR2 will activate causing input contactor CR1 to open.  
See Remote Control Leads Fault Protection  
Shutdown, Shorted Rectifier Fault Protection and Idle  
Shutdown Timer in the Operation Section.  
4
Indicates an over current shutdown. See Over Current  
Protection Shutdown in the Operation Section.  
5
6
Indicates output current is present.  
Indicates that the machine is in the CC mode. LED 6  
should be on whenever LED 1 is lit.  
7
8
Indicates that the +16 VDC power supply is functioning.  
This circuitry is located on the control board.  
Indicates the control signal is being generated to control  
the firing of the output SCRs. This signal is sent to the  
firing board. This LED should get dimmer as the output  
voltage is increased. This LED will normally be off when  
the machine is in the constant current mode at open  
circuit.  
9
Indicates that the -10 VDC power supply is functioning.  
This circuitry is located on the control board.  
10  
11  
Indicates that 42 VAC is being supplied to the control  
board from the control board T3 transformer.  
Indicates that feedback voltage is present. This informa-  
tion is used when the machine is in the CC mode. This  
LED should get brighter as the output voltage is  
increased.  
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F-43  
F-43  
TROUBLESHOOTING & REPAIR  
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM  
CONSTANT CURRENT MODE – NO LOAD  
0 volts  
2 ms  
50 volts  
This is the typical DC open circuit  
voltage waveform generated from a  
properly operating machine. Note  
that each vertical division represents  
50 volts and that each horizontal divi-  
sion represents 2 milliseconds in  
time.  
Note: Scope probes connected at  
machine output terminals: (+) probe  
to positive terminal, (-) probe to neg-  
ative high inductance terminal.  
SCOPE SETTINGS  
Volts/Div.....................50V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling ............................DC  
Trigger .........................Internal  
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F-44  
F-44  
TROUBLESHOOTING & REPAIR  
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM  
CONSTANT VOLTAGE MIG  
MAXIMUM OUTPUT SETTING – NO LOAD  
0 volts  
2 ms  
50 volts  
This is the typical DC open circuit  
voltage waveform generated from a  
properly operating machine. Note  
that each vertical division represents  
50 volts and that each horizontal divi-  
sion represents 2 milliseconds in  
time.  
Note: Scope probes connected at  
machine output terminals: (+) probe  
to positive terminal, (-) probe to neg-  
ative high inductance terminal.  
SCOPE SETTINGS  
Volts/Div.....................50V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling ............................DC  
Trigger .........................Internal  
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F-45  
F-45  
TROUBLESHOOTING & REPAIR  
NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM  
CONSTANT VOLTAGE MIG  
MINIMUM OUTPUT SETTING – NO LOAD  
0 volts  
2 ms  
20 volts  
This is the typical DC open circuit  
voltage waveform generated from a  
properly operating machine. Note  
that each vertical division represents  
20 volts and that each horizontal divi-  
sion represents 2 milliseconds in  
time.  
Note: Scope probes connected at  
machine output terminals: (+) probe  
to positive terminal, (-) probe to neg-  
ative high inductance terminal.  
SCOPE SETTINGS  
Volts/Div.....................20V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling ............................DC  
Trigger .........................Internal  
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F-46  
F-46  
TROUBLESHOOTING & REPAIR  
TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED  
CONSTANT VOLTAGE MIG MODE  
0 volts  
20 volts  
2 ms  
This is the typical DC open circuit voltage wave-  
form generated from a properly operating  
machine. Note that each vertical division repre-  
sents 20 volts and that each horizontal division  
represents 2 milliseconds in time. The machine  
was loaded with a resistance grid bank. The  
grid bank meters read 650 amps at 44 VDC.  
Note: Scope probes connected at machine out-  
put terminals: (+) probe to positive terminal, (-)  
probe to negative high inductance terminal.  
SCOPE SETTINGS  
Volts/Div.....................20V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling ............................DC  
Trigger .........................Internal  
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F-47  
F-47  
TROUBLESHOOTING & REPAIR  
TYPICAL SCR GATE VOLTAGE WAVEFORM  
CONSTANT VOLTAGE MIG  
MAXIMUM OUTPUT SETTING – NO LOAD  
0 volts  
2 volts  
5 ms  
This is the typical DC open circuit voltage wave-  
form. The machine was in an open circuit con-  
dition (no load) and operating properly. Note  
that each vertical division represents 2 volts and  
that each horizontal division represents 5 milli-  
seconds in time.  
Note: Scope probes connected at SCR gate  
and cathode: (+) probe to gate, (-) probe to  
cathode.  
SCOPE SETTINGS  
Volts/Div.......................2V/Div.  
Horizontal Sweep.....5 ms/Div.  
Coupling ............................DC  
Trigger .........................Internal  
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F-48  
F-48  
INSTALLATION  
ABNORMAL OPEN CIRCUIT VOLTAGE WAVEFORM  
CONSTANT VOLTAGE MIG  
ONE OUTPUT SCR NOT FUNCTIONING  
0 volts  
20 volts  
2 ms  
This is NOT the typical DC open circuit voltage  
waveform. One output SCR is not functioning.  
Note the “gap” in the waveform. One SCR gate  
is disconnected to simulate an open or non-  
functioning output SCR. Each vertical division  
represents 20 volts and each horizontal division  
represents 2 milliseconds in time.  
Note: Scope probes connected at machine out-  
put terminals: (+) probe to positive terminal, (-)  
probe to negative high inductance terminal.  
SCOPE SETTINGS  
Volts/Div.....................20V/Div.  
Horizontal Sweep.....2 ms/Div.  
Coupling ............................DC  
Trigger .........................Internal  
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F-49  
F-49  
TROUBLESHOOTING & REPAIR  
INPUT CONTACTOR (CR1) CLEANING/REPLACEMENT  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
DESCRIPTION  
The following procedure will aid the technician in inspecting, cleaning, and replacing the input  
contactor.  
MATERIALS NEEDED  
Phillips head screw driver  
5/16” Socket wrench  
Flat head screw driver  
Low pressure air source  
Allen head type wrench  
IDEALARC DC-655  
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F-50  
F-50  
TROUBLESHOOTING & REPAIR  
INPUT CONTACTOR (CR1) CLEANING/REPLACEMENT (continued)  
FIGURE F.18 - INPUT CONTACTOR CLEANING AND REMOVAL  
1. INPUT SUPPLY LINE  
2. INPUT CONTACTOR CR1  
3. RECONNECT PANEL  
CLEANING PROCEDURE  
CONTACTOR REPLACEMENT  
PROCEDURE  
1. Remove the main input supply power to the  
machine.  
1. Disconnect main input supply power to the  
machine.  
2. Locate and get access to the input contac-  
tor (CR1) in the input box. See Figure F.18.  
2. Locate and get access to the input contac-  
tor (CR1) in the input box. See Figure F.18.  
3. Remove the input contactor cover plate  
using a phillips head screwdriver.  
3. Disconnect the main input supply power  
leads L1, L2, and L3 to the input contactor.  
WARNING  
Remove the control transformer primary  
leads H1, H2 or H3 (dependent on input volt-  
age) from the L1 and L3 terminals on the  
input side of the contactor.  
Do not apply input power to  
the machine with the input  
contactor cover plate re-  
moved.  
4. Disconnect the output leads T1, T2, and T3  
from the input contactor.  
5. Identify and label the leads connected to the  
input contactor coil.  
Diagram.  
See the Wiring  
4. Blow out any dirt or dust in or around the  
contacts with a low pressure air stream.  
6. Disconnect the leads from the input contac-  
tor coil (leads X1, #256 and #255A). See the  
Wiring Diagram.  
5. Inspect the contacts for signs of excessive  
wear, pitting, or contacts fused (stuck)  
together.  
7. Remove the three self-tapping mounting  
screws using a 5/16” socket wrench.  
a. If any of these conditions are present,  
replace the input contactor assembly.  
8. Remove the input contactor.  
6. Replace the input contactor cover plate.  
9. Insert the replacement input contactor and  
install it following the procedures in reverse  
order.  
NOTE: Be sure to reconnect all leads cor-  
rectly.  
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F-51  
F-51  
TROUBLESHOOTING & REPAIR  
SCR RECTIFIER BRIDGE REMOVAL AND  
REPLACEMENT PROCEDURE  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
DESCRIPTION  
The following procedure will aid the technician in removing the SCR/Rectifier Bridge for main-  
tenance or replacement.  
MATERIALS NEEDED  
1/2” Socket wrench  
3/8” Wrench  
1/2” Wrench  
9/16” Wrench  
IDEALARC DC-655  
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F-52  
F-52  
TROUBLESHOOTING & REPAIR  
SCR RECTIFIER BRIDGE REMOVAL AND  
REPLACEMENT PROCEDURE (continued)  
FIGURE F.19 - THERMAL FAN/SNUBBER BOARD PLUG LOCATIONS  
THERMAL FAN / SNUBBER L10124-[ ]  
LED2  
LED6  
LED5  
LED1  
LED4  
LED3  
PLUG J20  
PLUG J9  
PROCEDURE  
1. Remove the input power to the DC-655  
machine.  
4. Disconnect lead #222 from the negative high  
inductance output terminal. This lead runs  
from plug J9 to the negative high inductance  
output terminal. Cut any necessary cable  
ties. See the Wiring Diagram.  
2. Using the 3/8” wrench, remove the case top  
and sides.  
3. Locate and remove plugs J9 and J20 from  
the Thermal Fan/Snubber Board. See Figure  
F.19.  
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F-53  
F-53  
TROUBLESHOOTING & REPAIR  
SCR RECTIFIER BRIDGE REMOVAL AND  
REPLACEMENT PROCEDURE (continued)  
FIGURE F.20 – SCR RECTIFIER BRIDGE ASSEMBLY DETAILS  
MAIN TRANSFORMER  
SECONDARY LEADS  
SCR  
RECTIFIER  
BRIDGE  
LEG  
ASSEMBLY  
MOUNTING  
BRACKETS  
5. Using the 1/2” socket wrench, remove the  
six transformer secondary leads from the  
heat sink assembly. The small “A” leads do  
not have to be removed. Note lead place-  
ment for reassembly. See the Wiring  
Diagram and Figure F.20.  
REASSEMBLY  
1. Upon reassembly, apply a thin coating of  
Dow Corning 340 Heat Sink Compound to  
all bolted connections.  
2. With the left side horizontal mounting brack-  
et removed, slide the heat sink assembly  
into the machine.  
6. With the 9/16” wrench, remove the shunt  
from the left side of the heat sink assembly.  
3. Support the heat sink assembly and install  
the left side mounting bracket. Then mount  
the heat sink assembly to the bracket with  
four bolts. Note insulator placement.  
7. With the 3/8” wrench, remove the four  
mounting bolts that hold the heat sink  
assembly to the horizontal mounting brack-  
ets. Be sure to remove the insulators and  
take note of placement for reassembly.  
4. Attach the shunt to the left side of the heat  
sink assembly.  
8. While supporting the heat sink assembly,  
remove the left side horizontal mounting  
bracket from the left side leg assembly. See  
Figure F.20.  
5. Install the six transformer secondary leads  
to the heat sink assembly. See the Wiring  
Diagram.  
9. Carefully slide the rectifier heat sink assem-  
bly from the machine. Clear all leads.  
6. Connect lead #222 to the high inductance  
output terminal.  
7. Install plugs J9 and J20 onto the thermal  
fan/snubber board.  
8. Replace any cable ties cut at disassembly.  
9. Install the case top and sides.  
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F-54  
F-54  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER AND CHOKE REMOVAL  
AND REPLACEMENT PROCEDURE  
WARNING  
Service and repair should be performed by only Lincoln Electric factory trained personnel.  
Unauthorized repairs performed on this equipment may result in danger to the technician or  
machine operator and will invalidate your factory warranty. For your safety and to avoid elec-  
trical shock, please observe all safety notes and precautions detailed throughout this manu-  
al.  
If for any reason you do not understand the test procedures or are unable to perform the  
test/repairs safely, contact the Lincoln Electric Service Department for electrical trou-  
bleshooting assistance before you proceed. Call 216-383-2531 or 1-800-833-9353 (WELD).  
DESCRIPTION  
The following procedure will aid the technician in removing the main transformer and choke  
for maintenance or replacement.  
MATERIALS NEEDED  
3/8” Wrench  
7/16” Wrench  
9/16” Wrench  
Wire cutters  
Soldering iron and solder  
1/2” Socket wrench  
9/16” Socket wrench  
IDEALARC DC-655  
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F-55  
F-55  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER AND CHOKE REMOVAL  
AND REPLACEMENT PROCEDURE (continued)  
FIGURE F.21 – OUTPUT CHOKE/MAIN TRANSFORMER ASSEMBLY DETAILS  
CHOKE THERMOSTAT  
(LEADS #273 AND 41A)  
TOP LEAD (#222A)  
CENTER TAP  
(LOW INDUCTANCE  
OUTPUT LEAD)  
CHOKE / FRAME  
MOUNTING  
BOLTS (4)  
ROPE SLING  
BOTTOM CHOKE  
LEAD (HIGH  
INDUCTANCE  
OUTPUT LEAD)  
IRON/COIL  
MOUNTING  
BOLTS (4)  
TRANSFORMER  
SECONDARY  
LEADS (6)  
6. Using the 9/16” wrench, remove the high  
inductance output lead from the bottom  
choke lead. See Figure F.21.  
PROCEDURE  
1. Remove the input power to the DC-655  
machine.  
7. Support the choke with a crane or hoist.  
2. Remove the case top and sides.  
8. Using the 9/16” wrench, remove the four  
bolts, washers and nuts mounting the choke  
assembly to the transformer frame assem-  
bly.  
OUTPUT CHOKE REMOVAL  
3. Label and remove leads #273 and 41A from  
the choke thermostat.  
9. Carefully lift the choke from the DC-655  
machine.  
4. Using the 9/16” wrench, remove the flexible  
transformer secondary lead and the #222A  
lead from the top lead of the output choke.  
See Figure F.21.  
5. Using the 9/16” wrench, remove the low  
inductance output lead from the center tap  
of the choke. See Figure F.21.  
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F-56  
F-56  
TROUBLESHOOTING & REPAIR  
MAIN TRANSFORMER AND CHOKE REMOVAL  
AND REPLACEMENT PROCEDURE (continued)  
MAIN TRANSFORMER REMOVAL  
REASSEMBLY  
10. With the 1/2” wrench, remove the six trans-  
former secondary leads from the SCR heat  
sink assembly.  
1. Using the rope sling, carefully position the  
iron/coil assembly onto the DC-655. Mount  
it to the frame assembly with four bolts,  
washers and nuts.  
11. Remove the transformer primary leads from  
the reconnect panel. Label for reassembly.  
2. Attach the transformer primary leads to the  
reconnect panel.  
12. Carefully label and unsolder the following  
leads from the transformer windings. Cut  
any necessary cable ties. See the Wiring  
Diagram.  
3. Attach the six transformer secondary leads  
to the SCR heat sink assembly.  
4. Solder the following leads to the transformer  
windings.  
335  
336  
331  
332  
333  
334  
203  
204  
205  
206  
207  
208  
31  
335  
336  
331  
332  
333  
334  
203  
204  
205  
206  
207  
208  
31  
32A  
41  
32A  
41  
42A  
41  
42A  
41  
thermostat  
thermostat  
13. Using a rope sling and hoist, support the  
iron/coil assembly. See Figure F.21.  
5. Using a crane or hoist, carefully place the  
choke onto the main transformer.  
14. With the 9/16” wrench, remove the four  
bolts, washers and nuts holding the iron/coil  
assembly to the frame assembly.  
6. Attach the high inductance output lead to  
the bottom choke lead.  
15. Cut or remove any necessary cable ties.  
7. Attach the low inductance output lead to the  
choke center tap.  
16. Using the hoist, carefully remove the  
iron/coil assembly from the DC-655  
machine. Clear all leads.  
8. Attach the #222A lead and flexible trans-  
former secondary lead to the top choke  
lead.  
9. Attach leads #273 and 41A to the choke  
thermostat.  
10. Replace any cable ties cut at disassembly.  
11. Install the case top and sides.  
IDEALARC DC-655  
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F-57  
F-57  
TROUBLESHOOTING & REPAIR  
RETEST AFTER REPAIR  
Should a machine under test be rejected for any reason requiring the removal of any mechanical part that could  
affect the machine’s electrical characteristics, or if any electrical components are repaired or replaced, the machine  
must be retested.  
INPUT IDLE AMPS AND WATTS  
Input volts/Phase/Hertz  
208/3/60  
Maximum Idle Amps  
Maximum Idle KW  
11.0  
10.0  
6.0  
5.5  
5.0  
1.0  
1.0  
1.0  
1.0  
1.0  
1.0  
1.0  
230/3/60  
380/3/60  
416/3/60  
460/3/60  
550/3/60  
575/3/60  
4.2.  
4.0  
200/3/50  
220/3/50  
230/3/50  
380/3/50  
400/3/50  
415/3/50  
440/3/50  
500/3/50  
550/3/50  
21.0  
19.1  
18.3  
11.0  
10.5  
10.1  
9.6  
1.3  
1.3  
1.3  
1.3  
1.3  
1.3  
1.3  
1.3  
1.3  
8.4  
7.7  
MAXIMUM OPEN CIRCUIT VOLTAGES  
Mode  
Input Hertz  
Open Circuit Volts  
CC Stick  
60  
66/70  
CV MIG  
60  
60  
60  
44/47  
Auxiliary Output (#31-#32)  
Auxiliary Output (#41-#42)  
122/128 VAC  
44/48 VAC  
MINIMUM ACCEPTABLE OUTPUT VOLTAGE - AT MAXIMUM OUTPUT SETTINGS  
Mode  
CC Stick  
Control Settings  
Output Control at Maximum  
Arc Force Control at  
Minimum  
Load  
815 Amps @ 44.0 Volts (Min)  
CV MIG  
Output Control at Maximum  
815 Amps @ 44.0 Volts (Min)  
5 Amps @ 120/126 VAC (Min)  
5 Amps #41/45 VAC (Min)  
Auxiliary Output (#31-#32)  
Auxiliary Output (#41-#42)  
N/A  
N/A  
IDEALARC DC-655  
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SVM ERROR REPORTING FORM  
We need to know if there are errors in our manuals. We also value any suggestions as to  
additional tests or procedures that would make this SVM a better tool for you.  
If you discover new or different “Problems or Symptoms” that are not covered in the three col-  
umn troubleshooting chart, please share this information with us. Please include the  
machine’s code number and how the problem was resolved.  
Thank You,  
Technical Services Group  
Lincoln Electric Co.  
22801 ST. Clair Ave.  
Cleveland, Ohio 44117-1199  
FAX 216-481-2309  
SVM Number ___________________________  
Page Number if necessary__________________  
Your Company__________________________  
Your Name_____________________________  
Please give detailed description below:  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
___________________________________________________________________________  
SD287 01/99  
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G-1  
G-1  
ELECTRICAL DIAGRAMS  
TABLE OF CONTENTS  
ELECTRICAL DIAGRAMS SECTION  
Electrical Diagrams Section...........................................................................................Section G  
Wiring Diagram (60 Hz Domestic) (G3348-1)..............................................................................G-2  
Control Board Schmatic (G3384) ................................................................................................G-3  
Firing Board Schmatic (G2792)...................................................................................................G-4  
Thermal Fan/Snubber P.C. Board Schematic (L10123)...............................................................G-5  
Control Board Layout (G3385-1) .................................................................................................G-6  
Firing Board Layout (G2699-2)....................................................................................................G-7  
Thermal Fan/Snubber Board Layout (L10124-1).........................................................................G-8  
DC 655  
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G-2  
G-2  
ELECTRICAL DIAGRAMS  
Wiring Diagram (G3348-1)  
P15  
75  
75  
76  
77  
J15  
75  
75  
76  
77  
10A 42V CIRCUIT BREAKER  
8
7
6
5
4
3
2
1
1
2
DUAL (EXCEPT 380/500V  
UNDER 346 VOLTS (SHOWN CONNECTED FOR LOW VOLTAGE)  
&
230/400V)  
&
SINGLE VOLTAGE  
OUTPUT  
J14  
202  
201  
210  
315  
215  
317  
222  
202  
201  
210  
42A  
42  
1
2
3
CONTROL  
AM  
-
32  
3
4
TO  
SUPPLY  
LINES  
10K  
R1  
N.D.  
H3  
RECONNECT  
PANEL  
.0045MFD  
3000V  
236  
237  
75  
R3  
2
4
77  
5
H2  
4
5
6
7
8
3
2
1
-
VM  
X1  
6
2
2
C9  
C8  
C7  
GND.  
STUD  
L3  
L1  
L2  
TO  
10K 1/4W  
7
41  
41  
J16  
RECONNECT  
PANEL  
OPTIONAL  
ANALOG METERS  
222  
8
210  
210  
11  
10  
12  
3
2
1
9
8
7
6
5
TO GROUND PER  
NATIONAL  
20A  
W
V
32  
32A  
32A  
31  
76  
75  
21  
41  
42  
9
115V  
SW3  
CIRCUIT  
10  
11  
12  
13  
14  
4
41  
41  
9
4
41  
41  
ELECTRICAL  
CODE  
31  
N.E.  
76  
77  
OUTPUT  
CONTROL  
SWITCH  
238  
226  
OR  
256  
BREAKER  
8
7
6
5
4
3
2
1
10  
11  
12  
13  
14  
115V RECEPTACLE  
4
U
202  
201  
210  
315  
215  
317  
222  
336  
334  
333  
335  
332  
331  
6
5
4
3
2
CR  
1
32A  
222  
32A  
CONTACTOR  
J12  
J13  
42A  
222  
42A  
222  
FLEX  
LEAD  
32  
31  
TO PRIMARY  
COILS  
2
CONNECT OR INSULATE  
AS SHOWN ON INPUT  
CONNECTION DIAGRAM  
237  
236  
H1  
255A  
31  
1
210  
OPTIONAL DIGITAL  
METER P.C. BOARD  
T.S.2  
SINGLE VOLTAGE OVER 345 VOLTS  
TO  
+21 -21 41  
4
T.S.1  
2
2
31 32  
4
75 76 77  
H4  
H3  
H2  
H1  
X2  
N.D.  
H2  
RECONNECT  
PANEL  
SUPPLY  
LINES  
OPTIONS  
H3  
2
255  
255  
211  
OUTPUT  
TERMINAL  
SWITCH  
X1  
L3  
L1  
L2  
X1  
SW1  
POWER SWITCH  
282  
T2 CONTROL  
TRANSFORMER  
SW5  
11  
3
2
1
RED  
281  
TO GROUND PER  
NATIONAL  
ELECTRICAL  
CODE  
4
W
BLK  
10  
12  
T3  
V
CONTROL  
256  
255  
BOARD  
U
TRANSFORMER  
CR  
1
1
2
3
4
5
6
7
8
9
10  
255  
CONTACTOR  
TO PRIMARY  
COILS  
201  
202  
75  
1
1
2
3
PILOT  
J3  
H1  
255A  
W
256  
LIGHT  
2
3
4
256  
4
5
6
7
8
5
J2  
314  
226  
336  
335  
6
THERMAL  
PROTECTION  
231  
210  
281  
J1  
7
41  
Y
305  
BRASS  
TERMINAL  
LIGHT  
8
317  
+
-
9
N.J.  
S1  
9
41  
10  
282  
238  
318  
310  
309  
315  
222A  
10  
11  
12  
13  
14  
S
T1 MAIN  
TRANSFORMER  
42V  
11  
12  
N.F.  
F
SECONDARY  
THERMOSTAT  
1
2
3
4
41  
41  
CONTROL  
P.C. BOARD  
333  
10V  
OFF  
S
273  
41  
41A  
CHOKE LEAD  
41A  
41  
301  
F
1
2
3
J21  
8
41  
334  
THERMOSTAT  
42A  
1
2
3
4
5
6
7
9
10 11 12 13 14 15 16  
331  
10V  
S
F
2
3
G1  
G2  
G3  
G4  
G5  
G6  
1
4
5
6
7
8
1
2
5
32A  
31  
208  
207  
206  
205  
2
332  
42A  
S
F
3
4
5
6
J5  
J4  
J7  
115V  
S
PRI.  
4
45V  
41  
6
9
4
31  
31  
F
310  
309  
215  
231  
10  
11  
12  
13  
14  
15  
N.A.  
1
2
3
4
5
6
A
B
7
8
9
203  
205  
207  
W
B
F
F
F
N.G.  
FAN  
MOTOR  
1
2
3
32V  
32V  
32V  
13  
PRI.  
10  
14  
15  
12  
214  
203  
204  
261  
262  
263  
B'  
C
C'  
S
S
S
341  
204  
AUX1  
206  
208  
J22  
261  
32  
11  
P22  
261  
262  
263  
342  
16  
GREEN  
4
5
6
7
8
1
1
7
8
2
4
77  
2
3
4
262  
263  
342  
2
A'  
J6  
3
215  
FIRING CIRCUIT  
P.C. BOARD  
P16  
300  
4
SEC.  
SEC.  
42  
32  
31  
9
31  
76  
75  
21  
41  
42  
GREEN  
OUTPUT CHOKE  
41  
21  
STANDARD  
10  
11  
12  
13  
14  
LOW  
2
4
14-PIN  
(-)  
319  
340  
215  
344  
RECEPTACLE  
(FRONT VIEW)  
THERMAL FAN  
THERMISTOR  
HIGH  
315  
318  
317  
41  
75  
1
1
2
3
4
5
6
7
NTC  
77  
(-)  
76  
2
J11  
222A  
316  
32A  
300  
G2  
3
4
222  
222  
222  
SW2  
222  
210  
N.H.  
J10  
MODE  
SWITCH  
14  
13  
314  
301  
305  
A4  
TP3  
222  
(SHOWN IN CC  
POSITION)  
ARC FORCE  
G1  
G4  
A5  
12  
11  
10  
10K  
R4  
322  
320V  
160J  
8
30  
A1  
A3  
A5  
328  
R2  
(ALL 3)  
300W  
DUAL FEEDER P.C. BOARD  
321  
OPTIONS  
C2 TP2  
TP1  
C6  
G5  
319  
316  
9
1
2
J20  
A6  
A3  
A2  
A1  
G3  
G6  
222  
C
.05MFD  
8
1
210  
J9  
600V  
7
255  
1
2
3
4
2
3
214  
261  
(ALL 3)  
G6  
6
5
6
5
4
3
2
32  
GREEN  
2
4
77  
262  
SCR  
3
SCR  
SCR  
1
NC  
NO  
COM  
G3  
G1  
G5  
G5  
G4  
G3  
G2  
G1  
263  
342  
4
5
6
7
8
5
255A  
OUTPUT SHUNT  
(50 MV @800 AMPS)  
4
C1  
(+)  
J8  
3
CR  
2
J23  
2
1
+
-
J17  
J19  
J18  
346  
FOR OPTIONAL  
1
42  
PARALLELING KIT  
32  
77  
31  
9
31  
76  
75  
21  
41  
42  
THERMAL FAN/  
SNUBBER P.C. BOARD  
201 202  
GREEN  
OUTPUT  
41  
21  
10  
11  
12  
13  
14  
345  
1
2
3
2
4
215  
14-PIN  
RECEPTACLE  
(RIGHT)  
32  
GREEN  
2
4
75  
(FRONT VIEW)  
4
5
6
7
8
76  
G2  
G4  
G6  
OUTPUT  
RECTIFIER  
ASSEMBLY  
77  
JUMPER  
PLUG  
TO J16  
NOTES:  
SCR  
6
SCR  
4
SCR  
2
J6,J11  
J20  
1
J7,J10,J12,J14  
1
J3  
J4,J8,J13  
31  
76  
75  
21  
41  
42  
9
N.A. LEADS  
4
THRU  
9
ARE NOT PRESENT ON 380/500V,  
5
1
4
1
2
1
3
10  
11  
12  
13  
14  
AND SINGLE VOLTAGES OVER 345V MACHINES.  
1
2
3
A6  
A2  
A4  
3
4
4
6
N.D. TAPE UP SEPARATELY TO PROVIDE AT LEAST  
600V INSULATION.  
8
5
6
10  
2
32  
GREEN  
2
4
77  
4
5
6
7
8
J1,J9,J15,J16  
J17,J18,J19  
J2  
J5  
N.E. PLUG  
&
LEAD ASSEMBLY GOES TO EITHER J12 (OPTIONAL DIGITAL  
METERS PC BD.) OR J14 (IN LINE CONNECTOR FOR ANALOG METERS).  
1
6
1
7
1
8
42  
N.F. LOCATED IN SECONDARY COIL WINDING.  
32  
77  
31  
9
31  
76  
75  
21  
41  
42  
7
12  
14  
16  
8
9
GREEN  
41  
21  
10  
11  
12  
13  
14  
N.G. STANDARD 14-PIN RECEPTACLE PLUGS INTO J16 ON STANDARD  
MACHINES AND IS REPLACED BY DUAL FEEDER OPTION IF USED.  
2
4
14-PIN  
CONNECTOR CAVITY NUMBERING SEQUENCE  
(VIEWED FROM COMPONENT SIDE OF BOARD)  
RECEPTACLE  
(LEFT)  
75  
N.H. LOCATED ON OUTPUT RECTIFIER FLAT HEAT SINK.  
(FRONT VIEW)  
76  
N.J. AS SHIPPED ONLY SWITCH #4 IS ON (UP). SEE INSTRUCTION MANUAL.  
ELECTRICAL SYMBOLS PER E1537  
11-6-98  
G3348-1  
I-UF  
G3348-1  
NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclo-  
sure panels of your machine.  
DC 655  
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G-3  
G-3  
ELECTRICAL DIAGRAMS  
Control Board Schematic (G3384)  
POWER SUPPLY  
IDLE SHUTDOWN  
TIMER  
TIMER OUTPUT  
TIMER  
CHIP  
315  
315  
TIMER INPUT  
SHORTED SCR  
A.C. PROTECTION  
TO  
THERMAL FAN/  
SNUBBER PCB  
317  
TO  
THERMAL FAN/  
SNUBBER PCB  
TRIGGER  
OPEN  
318  
317  
ENABLE  
TO (+)  
OUTPUT STUD  
Vco  
CC  
VFB  
BUFFER  
CONTROL  
AMPLIFIER  
GAIN=27  
MODE  
HOT START  
SWITCHING  
SLOPE  
BUFFER  
ARC FORCE  
CC CONTROL  
REFERENCE  
FIRING  
INTERCEPT  
BUFFER  
CV  
INTERFACE  
VFB  
BUFFER  
CURRENT SWITCH  
0.5 SEC TIMER  
>15 AMP  
CURRENT  
SWITCH  
TO OPTIONAL  
DIGITAL METER PCB  
201  
REF  
COM  
CURRENT FEED  
BACK  
CV SUBARC FEEDBACK  
201  
HOLD  
LOW  
SHUT-  
DOWN  
CURRENT  
AMPLIFIER  
202  
202  
TO OPTIONAL  
DIGITAL METER PCB  
CV FEEDBACK  
CVI  
START  
OVER  
CURRENT  
PROTECTION  
CV CURRENT LIMITING  
REFERENCE  
-10V  
CONTROL POT  
REFERENCE  
PEAK  
CURRENT  
PROTECTION  
IDLE ZERO  
Ico  
REFERENCE  
REFERENCE  
SIGNAL  
POT FAULT  
BUFFER  
PROTECTION  
TO  
FIRING  
PCB  
A
G3384  
G3384  
A
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not avail-  
able from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in  
danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.  
DC 655  
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G-4  
G-4  
ELECTRICAL DIAGRAMS  
Firing Board Schematic (G2792)  
7-17-98A  
G2792  
G2792  
7-17-98A  
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not avail-  
able from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in  
DC 655  
danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.  
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G-5  
G-5  
ELECTRICAL DIAGRAMS  
Thermal Fan/Snubber Board Schematic (L10123)  
5-16-97A  
L10123  
L10123  
5-16-97A  
NOTE: Lincoln Electric assumes no responsibility for liablilities resulting from board level troubleshooting. PC Board repairs will invalidate your factory warranty. Individual Printed Circuit Board Components are not avail-  
able from Lincoln Electric. This information is provided for reference only. Lincoln Electric discourages board level troubleshooting and repair since it may compromise the quality of the design and may result in  
SQUARE WAVE TIG 275  
danger to the Machine Operator or Technician. Improper PC board repairs could result in damage to the machine.  
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G-6  
G-6  
ELECTRICAL DIAGRAMS  
Control Board Layout (G3385-1)  
CAPACITORS = MFD/VOLTS  
RESISTORS = OHMS/1/4 WATT UNLESS OTHERWISE SPECIFIED  
C-RW  
G3385-1  
DC 655  
G3385-1  
C-RW  
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G-7  
G-7  
ELECTRICAL DIAGRAMS  
Firing Board Layout (G2699-2)  
ITEM  
REQ'D  
PART NO.  
DESCRIPTION  
CAPACITORS  
RESISTORS  
=
MFD/VOLTS  
7-17-98A  
G2699-2  
=
OHMS  
DC 655  
G2699-2  
7-17-98A  
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G-8  
G-8  
ELECTRICAL DIAGRAMS  
Thermal Fan/Snubber Board Layout (L10124-1)  
8 . 7 5  
4 . 5 0  
. 2 5  
9 . 0 0  
0
0
. 2  
J 9  
J 8  
J 2 0  
J 1 0  
J 1 1  
R 3 1  
R 3 0  
R 2 9  
R 2 8  
C 2 3  
O C I 1  
C 2 6  
R 1 3  
R 1 2  
D 3  
C 1 7  
O C I 2  
T R I 1  
L E D 3  
R 2 4  
R 2 5  
R 2 6  
X 2  
Q 1  
L E D 1  
L E D 5  
L E D 4  
L E D 6  
X 3  
L E D 2  
X 1  
X 4  
C 9  
C 8  
5
L 1 0 1 2 4 - 1  
T H E R M A L F A N S N U B B E R  
~ . 0 4  
6
DC 655  
L10124-1  
5-16-97A  
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NOTES  
DC 655  
Download from Www.Somanuals.com. All Manuals Search And Download.  

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