Lincoln Welder LN 742 User Manual
RETURN TO MAIN MENU  
IM476-A  
August, 2005  
LN-742 & LN-742H Wire Feeders  
10027  
10028  
10048  
10049  
10238  
10239  
10240  
10241  
For use with machines having Code Numbers:  
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 thought-  
ful operation on your part. DO  
NOT INSTALL, OPERATE OR  
REPAIR THIS EQUIPMENT  
WITHOUT READING THIS  
MANUAL AND THE SAFETY  
PRECAUTIONS CONTAINED  
THROUGHOUT. And, most  
importantly, think before you act  
and be careful.  
OPERATOR’S MANUAL  
Copyright © 2005 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  
SAFETY  
ARC RAYS can burn.  
ELECTRIC SHOCK can  
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.  
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.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.  
fumes and gases.When welding, keep  
your head out of the fume. Use enough  
• AC Welder with Reduced Voltage Control.  
ventilation and/or exhaust at the arc to keep  
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.c. In semiautomatic or automatic wire welding, the electrode,  
electrode reel, welding head, nozzle or semiautomatic  
welding gun are also electrically “hot”.  
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.  
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.f. Maintain the electrode holder, work clamp, welding cable and  
welding machine in good, safe operating condition. Replace  
damaged insulation.  
3.g. Never dip the electrode in water for cooling.  
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.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.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.i. When working above floor level, use a safety belt to protect  
yourself from a fall should you get a shock.  
3.j. Also see Items 6.c. and 8.  
5.e. Also see item 1.b.  
Mar ‘95  
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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 cir-  
cuits. 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.  
Mar ‘95  
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iv  
SAFETY  
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.  
PRÉCAUTIONS DE SÛRETÉ  
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:  
6. Eloigner les matériaux inflammables ou les recouvrir afin de  
prévenir tout risque d’incendie dû aux étincelles.  
7. Quand on ne soude pas, poser la pince à une endroit isolé de  
la masse. Un court-circuit accidental peut provoquer un  
échauffement et un risque d’incendie.  
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 toujours  
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.  
b. Faire trés attention de bien s’isoler de la masse quand on  
soude dans des endroits humides, ou sur un plancher  
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.  
c. Maintenir le porte-électrode, la pince de masse, le câble  
de soudage et la machine à souder en bon et sûr état  
defonctionnement.  
8. S’assurer que la masse est connectée le plus prés possible  
de la zone de travail qu’il est pratique de le 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 lev-  
age, câbles de grue, ou autres circuits. Cela peut provoquer  
des risques d’incendie ou d’echauffement des chaines et des  
câbles jusqu’à ce qu’ils se rompent.  
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 fumeés toxiques.  
d.Ne jamais plonger le porte-électrode dans l’eau pour le  
refroidir.  
10. Ne pas souder en présence de vapeurs de chlore provenant  
d’opérations 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 fortement toxique)  
ou autres produits irritants.  
e. Ne jamais toucher simultanément les parties sous tension  
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.  
f. Si on utilise la machine à souder comme une source de  
courant pour soudage semi-automatique, ces precautions  
pour le porte-électrode s’applicuent aussi au pistolet de  
soudage.  
11. Pour obtenir de plus amples renseignements sur la sûreté,  
voir le code “Code for safety in welding and cutting” CSA  
Standard W 117.2-1974.  
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  
enrouler le câble-électrode autour de n’importe quelle partie  
du corps.  
PRÉCAUTIONS DE SÛRETÉ POUR  
LES MACHINES À SOUDER À  
TRANSFORMATEUR ET À  
REDRESSEUR  
3. Un coup d’arc peut être plus sévère qu’un coup de soliel,  
donc:  
a. Utiliser un bon masque avec un verre filtrant approprié  
ainsi qu’un verre blanc afin de se protéger les yeux du ray-  
onnement 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 rayonnement de  
l‘arc.  
1. Relier à la terre le chassis du poste conformement au code de  
l’électricité et aux recommendations du fabricant. Le dispositif  
de montage ou la piece à souder doit être branché à une  
bonne mise à la terre.  
c. Protéger l’autre personnel travaillant à proximité au  
soudage à l’aide d’écrans appropriés et non-inflammables.  
2. Autant que possible, I’installation et l’entretien du poste seront  
effectués par un électricien qualifié.  
4. Des gouttes de laitier en fusion sont émises de l’arc de  
soudage. Se protéger avec des vêtements de protection libres  
de l’huile, tels que les gants en cuir, chemise épaisse, pan-  
talons sans revers, et chaussures montantes.  
3. Avant de faires des travaux à l’interieur de poste, la debranch-  
er à l’interrupteur à la boite de fusibles.  
4. Garder tous les couvercles et dispositifs de sûreté à leur  
place.  
Mar. ‘93  
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for selecting a QUALITY product by Lincoln Electric. We want you  
to take pride in operating this Lincoln Electric Company product  
••• as much pride as we have in bringing this product to you!  
Thank You  
Please Examine Carton and Equipment For Damage Immediately  
When this equipment is shipped, title passes to the purchaser upon receipt by the carrier. Consequently, Claims  
for material damaged in shipment must be made by the purchaser against the transportation company at the  
time the shipment is received.  
Please record your equipment identification information below for future reference. This information can be  
found on your machine nameplate.  
Product _________________________________________________________________________________  
Model Number ___________________________________________________________________________  
Code Number or Date Code_________________________________________________________________  
Serial Number____________________________________________________________________________  
Date Purchased___________________________________________________________________________  
Where Purchased_________________________________________________________________________  
Whenever you request replacement parts or information on this equipment, always supply the information you  
have recorded above. The code number is especially important when identifying the correct replacement parts.  
On-Line Product Registration  
- Register your machine with Lincoln Electric either via fax or over the Internet.  
• For faxing: Complete the form on the back of the warranty statement included in the literature packet  
accompanying this machine and fax the form per the instructions printed on it.  
• For On-Line Registration: Go to our WEB SITE at www.lincolnelectric.com. Choose “Quick Links” and then  
“Product Registration”. Please complete the form and submit your registration.  
Read this Operators Manual completely before attempting to use this equipment. Save this manual and keep it  
handy for quick reference. Pay particular attention to the safety instructions we have provided for your protection.  
The level of seriousness to be applied to each is explained below:  
WARNING  
This statement appears where the information must be followed exactly to avoid serious personal injury or  
loss of life.  
CAUTION  
This statement appears where the information must be followed to avoid minor personal injury or damage to  
this equipment.  
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TABLE OF CONTENTS  
Page  
i-iv  
Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section A  
Technical Specifications - LN-742 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Mounting Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Input Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Work Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Gun and Cable Assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Gun Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Water Connections (For Water Cooled Guns) . . . . . . . . . . . . . . . . . . . . .  
GMAW Shielding Gas Hookup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
A-1  
A-2  
A-2  
A-5  
A-5  
A-5  
A-6  
A-7  
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section B  
Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Recommended Processes and Equipment . . . . . . . . . . . . . . . . . . . . . . .  
Controls and Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Acceleration Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
English or Metric Speed Display Units . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Drive Roll Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Idle Roll Pressure Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Wire Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Making a Weld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Wire Reel Changing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
B-1  
B-1  
B-1  
B-1  
B-2  
B-3  
B-3  
B-3  
B-3  
B-7  
B-8  
B-12  
B-12  
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section C  
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Flux System Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Power Input Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Welding Guns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Spindles, Stands, and Adapters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Attaching the Wire Reel Stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Drive Roll Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
C-1  
C-2  
C-3  
C-3  
C-4  
C-5  
C-6  
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section D  
Routine Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Periodic Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
D-1  
D-1  
Troubleshooting and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section E  
How To Use Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
E-1  
E-2  
Electrical Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section F  
Parts Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  
P-228  
LN-742 & LN-742H  
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A-1  
A-1  
INSTALLATION  
TECHNICAL SPECIFICATIONS – LN-742  
INPUT VOLTAGE  
40 to 42V 10%, 50/60 Hz, 4.0 Amps  
WIRE FEED SPEED  
SYSTEM  
LN-742  
WIRE SPEED RANGE  
50 in. to 770 in. per minute (1.25 to 19.5 m/min)  
80 in. to 1200 in. per minute (2.00 to 30.5 m/min)  
LN-742H  
WIRE DIAMETERS  
SYSTEM  
LN-742  
ELECTRODE  
SOLID  
DIAMETER  
0.025 in. through 1/16 in. (0.6 through 1.6 mm)  
0.025 in. through 0.045 in. (0.6 through 1.2 mm)  
0.045 in. through 3/32 in. (1.2 through 2.4 mm)  
0.035 in. (0.9 mm)  
LN-742H  
LN-742  
SOLID  
CORED  
CORED  
LN-742H  
TEMPERATURE RATING (ALL MODELS)  
OPERATING  
STORAGE  
-4˚F to 104˚F (-20˚C to +40˚C)  
-40˚F to 104˚F (-40˚C to +40˚C)  
PHYSICAL DIMENSIONS  
TOTAL WEIGHT  
LESS ELECTRODE  
BOTH LN-742 AND LN-742H  
LENGTH  
HEIGHT  
WIDTH  
9.62 in.  
(244 mm)  
9.76 in.  
(247 mm)  
10.89 in.  
(277 mm)  
2 ROLL FEEDER  
WITHOUT WIRE STAND  
24 lbs  
(11.0 kg)  
20.68 in.  
(525 mm)  
9.76 in.  
(247 mm)  
17.00 in.  
(432 mm)  
2 ROLL FEEDER  
WITH WIRE STAND (K377)  
34 lbs  
(15.5 kg)  
10.60 in.  
(269 mm)  
11.11 in.  
(282 mm)  
4 ROLL FEEDER  
WITHOUT WIRE STAND  
28.7 lbs  
(13.1 kg)  
11.60 in.  
(295 mm)  
4 ROLL FEEDER  
WITH WIRE STAND (K377)  
38.7 lbs  
(17.7 kg)  
21.66 in.  
(550 mm)  
11.60 in.  
(295 mm)  
17.00 in.  
(432 mm)  
ENVIRONMENTAL RATING (ALL MODELS)  
IP21 (IEC 529)  
LN-742 & LN-742H  
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A-2  
A-2  
INSTALLATION  
MOUNTING LOCATION  
1. Connect the end of the control cable with the 14-  
pin cable plug to the mating receptacle on the  
power source.  
The LN-742 wire feeders can be mounted directly on  
top of the power source providing that it is secure and  
level. The LN-742 can also be mounted to an  
undercarriage when portability is required. The LN-742  
should be installed upright on a horizontal surface.  
2. Connect the electrode lead to the power source  
output terminal of the desired polarity.  
A K178-1 mounting platform is available for mounting  
the LN-742 to the top of Idealarc power sources. Refer  
to Section C, Accessories, for details.  
3. Referring to Figure A.1, route the other end of the  
electrode cable through the large oval hole in the  
rear panel of the LN-742 case. Connect the  
electrode to the copper strap on the side of the  
gearbox using the stud and nut provided.  
INPUT CABLE CONNECTIONS  
Refer to Section C, Accessories, for descriptions of  
the various input cable assemblies available for the  
LN-742 wire feeder.  
FIGURE A.1 – INPUT CONTROL CABLE AND  
ELECTRODE CABLE CONNECTIONS.  
WARNING  
Turn input power off before connecting the LN-742  
wire feeder.  
------------------------------------------------------------------------  
For connecting an LN-742 to a specific Lincoln power  
source, follow steps 1 through 5, and refer to the  
connection diagram in Figure A.3. The welding cable  
used must be sized according to the current and the  
duty cycle of the application.  
CONTROL  
CABLE  
With input power disconnected at the source, install  
the input cable per connection diagram A.3, and  
complete the following instructions:  
NUT  
COPPER  
STRAP  
ELECTRODE  
STUD  
LN-742 & LN-742H  
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A-3  
A-3  
INSTALLATION  
FIGURE A.2 – STRAIN RELIEF CLAMP.  
4. Connect the remaining end of the control cable  
with the eight-socket cable plug to the mating  
receptacle on the LN-742.  
5. Referring to Figure A.2, install the input cable  
under the wire reel mounting stand strain relief  
clamp. Remove the screws holding the clamp to  
the base of wire reel mounting assembly. Put the  
input cable under the clamp and reinstall the  
screws.  
CONTROL  
CABLE  
The connection diagram, Figure A.3, shows the  
electrode as positive. To change polarity, turn the  
power source off. Reverse the electrode and work  
cables at the power source, and set the wire feeder  
voltmeter polarity switch on the power source to the  
proper polarity.  
STRAIN  
RELIEF  
CLAMP  
Pins not listed in the table in Figure A.3 are not  
connected on the cable.  
WIRE REEL  
MOUNTING  
ASSEMBLY  
ELECTRODE  
CABLE  
If using the K589-1 remote control kit, set the power  
source control switch to the “Remote” position.  
LN-742 & LN-742H  
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A-4  
A-4  
INSTALLATION  
FIGURE A.3 – LN-742 WIRE FEEDER TO LINCOLN POWER SOURCE – CONNECTION DIAGRAM.  
TURN INPUT POWER OFF  
BEFORE CONNECTING THE  
LN-742 WIRE FEEDER.  
WARNING  
ELECTRIC  
SHOCK  
CAN KILL  
LINCOLN  
POWER SOURCE  
14 PIN  
AMPHENOL  
LN-742  
WIRE FEEDER  
+
-
TO WORK  
LN-742  
INPUT CABLE  
ASSEMBLY  
ELECTRODE CABLE  
K=42  
K=42  
I=41  
I=41  
C=2  
H=21  
H=21  
C=2  
D=4  
E=77  
G=75  
F=76  
G=75  
F=76  
D=4  
E=77  
14-SOCKET BOX RECEPTACLE, FRONT VIEW  
AND 14-PIN CABLE PLUG, REAR VIEW  
14-SOCKET BOX RECEPTACLE, REAR VIEW  
AND 14-PIN CABLE PLUG, FRONT VIEW  
PIN LEAD FUNCTION  
2
TRIGGER CIRCUIT  
TRIGGER CIRCUIT  
OUTPUT CONTROL  
OUTPUT CONTROL  
OUTPUT CONTROL  
WORK  
C
D
4
E
77  
76  
75  
21  
41  
42  
F
G
H
I
42V AC  
K
42V AC  
FUNCTIONS ARE LISTED FOR REFERENCE  
ONLY AND EACH MAY OR MAY NOT BE  
PRESENT IN YOUR EQUIPMENT.  
CLEVELAND, OHIO U.S.A  
LN-742 & LN-742H  
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A-5  
A-5  
INSTALLATION  
Connect the control cable amphenol plug into the  
mating 5-cavity receptacle on the front of the control  
section below the keypad.  
WORK CABLE  
Connect a work lead of sufficient size and length  
(Table A.1) between the proper output stud on the  
power source and the work. Be sure the connection to  
the work makes tight metal-to-metal electrical contact.  
FIGURE A.4 – GUN CABLE CONNECTIONS.  
TABLE A.1 – WORK LEAD SPECIFICATIONS  
Copper Work Cable Size, AWG  
Current 60%  
Duty Cycle  
Up To 50 Ft  
(15.2 m )  
50 Ft-100 Ft  
(15.2-30.4 m )  
2
2
2
2
300 Amps  
400 Amps  
500 Amps  
600 Amps  
0 (53 mm )  
00 (67 mm )  
LOCKING  
KNOB  
2
2
00 (67 mm )  
000 (85 mm )  
2
2
00 (67 mm )  
000 (85 mm )  
2
2
000 (85 mm )  
0000 (107 mm )  
GUN AND CABLE ASSEMBLIES  
AMPHENOL  
PLUG  
The LN-742 can be used with several guns. In most  
cases, Lincoln guns and cables are shipped  
assembled, ready to weld. Use the gun and cable  
assembly for the electrode type (solid, Outershield , or  
Innershield) and electrode size to be used. Refer to  
Section C, Accessories, for different gun types.  
CONDUCTOR  
BLOCK  
GUN CABLE  
ASSEMBLY  
GUN CABLE CONNECTIONS  
Lay the cable out straight. Insert the connector on the  
welding conductor cable through the large hole in the  
front panel of the LN-742 and into the brass conductor  
block on the front of the gearbox. Refer to Figure A.4.  
Make sure it is all the way in and tighten the locking  
knob. Keep this connection clean and bright.  
LN-742 & LN-742H  
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A-6  
A-6  
INSTALLATION  
1. Using male 5/8-18 UNF left-hand thread fittings,  
connect appropriate water hoses to the coolant  
WATER CONNECTIONS  
(FOR WATER COOLED GUNS)  
inlet  
and outlet  
on the back of the LN-742.  
Connect the other ends of these hoses to the  
appropriate ports on your water cooling units.  
The LN-742 must have a K590-1 Water Solenoid Kit  
installed (see Section C, Accessories). Refer to  
Figure A.5 and perform the following steps:  
2. In the event the water line fittings on your water  
cooled gun are incompatible with the female quick  
connects on the front of the LN-742, male quick  
connects are provided for installation on 3/16 in.  
I.D. hose (customer to provide appropriate  
clamps). The feeder connectors self seal when  
disconnected.  
The maximum water pressure permitted for use with  
the LN-742 is 55 psi (3.8 bar).  
NOTE: If not using a Lincoln water cooler, and if your  
water cooling device is not designed for use with a  
waterline solenoid valve, you may remove the solenoid  
and screw the male fitting (after applying sealant)  
directly into the brass manifold block.  
FIGURE A.5 – WATER CONNECTIONS.  
LN-742 & LN-742H  
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A-7  
A-7  
INSTALLATION  
Customer must provide a cylinder of shielding gas, a  
pressure regulator, a flow control valve, and a hose  
from the flow valve to the gas inlet fitting of the LN-742.  
Install per Figure A.6 and the following:  
GMAW SHIELDING GAS HOOKUP  
WARNING  
Gas under pressure is explosive.  
Always keep gas cylinders in an  
upright position and chained to the  
1. Connect the supply hose from the gas cylinder  
flow valve outlet to the 5/8-18 female inert gas  
fitting on the back panel of the LN-742.  
undercarriage or  
a
stationary  
support. See American National  
Standard Z-49.1, “Safety In Welding  
2. Install the barbed fitting and union nut to the  
5/8-18 female inert gas fitting on the front of the  
LN-742. Connect 3/16 in. (4.8 mm) I.D. gas hose  
from the gun to the barbed fitting.  
And Cutting”, published by the  
American Welding Society.  
------------------------------------------------------------------------  
When the gun is to be removed, this fitting can be  
easily detached by loosening the union nut.  
The LN-742 can be used with any shielding gas  
recommended in the electrode’s product literature at a  
maximum pressure of 60 psi (4.1 bar). This may  
include gasses such as Argon, Helium and Nitrogen  
and blended gases such as Ar-He, Ar-N , Ar-O Ar-  
2
2,  
CO , CO , AR-CO ,-O .  
2
2
2
2
FIGURE A.6 – SHIELDING GAS HOOKUP.  
t
t
GAS  
HOSE  
INERT  
GAS  
FITTING  
GAS  
SUPPLY  
HOSE  
LN-742 & LN-742H  
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B-1  
B-1  
OPERATION  
OPERATING INSTRUCTIONS  
GENERAL DESCRIPTION  
Read and understand the entire Operation Section  
prior to operating the machine.  
The K617 LN-742 semiautomatic constant speed wire  
feeder is specifically equipped for gas metal arc  
welding using flux-cored Outershield electrodes and  
solid wire. The LN-742 is also suitable for self-shielded  
flux-cored Innershield electrodes, submerged arc  
welding (if constant voltage is satisfactory), and other  
open arc welding. It has been factory assembled with  
the following features:  
SAFETY PRECAUTIONS  
WARNING  
• Wire feed control [50 to 770 in./min (1.25 to 19.5  
m/min) for the LN-742; 80 to 1200 in./min (2.00 to  
30.5 m/min) for the LN-742H].  
ELECTRIC SHOCK  
can kill.  
• Do not touch electrically live parts  
or electrode with skin or wet  
clothing.  
• Factory installed gas solenoid valve and gas  
fittings.  
• Wire drive uses a permanent magnet motor and  
includes tool-less “quick-release” idle roll pressure  
arm, outgoing guide tube and gun cable fastening.  
• Insulate yourself from work or  
ground.  
• Always wear dry insulating  
• Optional factory installed water solenoid and fittings  
gloves.  
for use with water cooled welding guns.  
FUMES AND GASES  
can be dangerous.  
The LN-742 4-Roll is designed to provide the additional  
feeding force required when using gun cables over 15  
ft (4.6 m) long or when the wire is pulled long distances  
(such as when bulk packages are used). Because the  
four-roll feeder has twice the contact surface, it can  
also help when feeding softer wires by delivering the  
same or more feeding force as the two-roll with less  
overall wire deformation.  
•
•
Keep your head out of fumes.  
Use ventilation or exhaust to  
remove fumes from breathing  
zone.  
WELDING SPARKS  
can cause fire or explosion.  
RECOMMENDED PROCESSES AND  
EQUIPMENT  
• Keep flammable material away.  
The LN-742 is recommended for use in MIG and  
Innershield welding applications with constant voltage  
power sources with 42 VAC auxiliary power and a 14-  
pin connector receptacle, such as the Invertec V300-  
PRO, V350-PRO, DC-400, DC-600, DC-655 DC-650-  
PRO, or Lincoln CV type power sources.  
• Do not weld on containers that  
have held combustibles.  
ARC RAYS  
can burn.  
• Wear eye, ear, and body  
The LN-742 is capable of the following wire feed  
ranges:  
protection.  
Observe additional Safety Guidelines detailed in  
the beginning of this manual.  
•
0.025 to 1/16 in. (0.6 to 1.6 mm) solid wire for gas-  
metal-arc or CV submerged arc processes.  
• 0.045 to 3/32 in. (1.2 to 2.4 mm) cored wire for  
Outershield gas-metal-arc processes.  
LN-742 & LN-742H  
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B-2  
B-2  
OPERATION  
• 0.045 to 5/64 in. (1.2 to 2.0 mm) cored wire for  
The top light indicates standard (two-step) trigger  
mode. In this mode the unit will only be active when  
the trigger is pressed. The middle light indicates lock  
(four-step) trigger mode. In this mode the solenoid is  
energized when the trigger is pressed, the power  
source and wire feeder are energized after preflow  
time when the trigger is released. Closing the trigger a  
second time turns off the wire feeder and then the  
power source after burnback time. Releasing the  
trigger a second time turns off the solenoid after  
Burnback time. The bottom light indicates spot weld  
trigger mode. Closing the trigger allows a single,  
timed, weld cycle. The duration of the weld cycle is set  
with the time selection controls. The spot on timer  
starts when welding current flows.  
Innershield processes.  
The LN-742H is capable of the following wire feed  
ranges:  
•
•
0.025 to 0.045 in. (0.6 to 1.2 mm) solid wire for gas-  
metal-arc or CV submerged arc processes.  
0.035 to 0.045 in. (1.2 mm) cored wire for  
Outershield, Metalshield or Innershield processes.  
CONTROLS AND SETTINGS  
The operator controls are located on the keypad  
shown in Figure B.1. The keypad consists of: 7  
membrane keys with tactile-feel embossed domes,  
that are generously spaced to provide easy selection,  
even while wearing welding gloves; a long-life, 3-1/2  
digit, 7 segment LED display with 0.56 in. (14.2 mm)  
character height, permitting easy viewing even from  
long gun cable distances; and high intensity, red, LED  
indicator lights that allow for viewing at almost any  
angle.  
TIME SELECTION CONTROLS. This control enables  
the operator to choose which timer will be displayed  
as shown by the indicator lights. Pressing the key  
causes the mode lights to sequence (from top to  
bottom). Any timers not available to the currently  
selected mode will be skipped. Times displayed in the  
LED display are adjusted using the setting adjustment  
arrows to the left of the LED display. The top left light  
indicates the preflow time is being displayed in  
seconds. The top right indicator light indicates the  
postflow time is being displayed in seconds. The  
middle light indicates the burnback time is being  
displayed in seconds. The bottom light indicates the  
spot weld time is being displayed in seconds.  
TRIGGER MODE CONTROLS. This control enables  
the operator to choose the mode of operation as  
shown by the indicator lights. Pressing the key causes  
the mode lights to sequence (from top to bottom).  
FIGURE B.1 – WIRE FEEDER CONTROLS.  
GAS  
PURGE  
KEY  
COLD  
INCH  
KEY  
COLD INCH  
GAS PURGE  
SETTING  
ADJUSTMENT  
ARROW KEYS  
LED  
DISPLAY  
OLTMETER  
INCH  
WFS  
FUNCTION  
SELECTION  
CONTROLS  
TRIGGER MODE  
TIME  
PREFLOW  
t1  
POSTFLOW  
t2  
STD  
TIMER  
SELECTION  
CONTROLS  
BURNBACK  
SPOT  
LOCK  
SPOT  
t
TRIGGER  
MODE  
t
CONTROLS  
t
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B-3  
B-3  
OPERATION  
FUNCTION SELECTION CONTROLS. This control  
enables the operator to select the function that will be  
displayed as shown by the indicator lights. Pressing  
the key causes the mode lights to sequence (from top  
to bottom). Settings displayed in the LED display are  
adjusted using the setting adjustment arrows to the  
left of the LED display. The top light indicates the arc  
voltage is being displayed in volts. The middle light  
indicates the inch speed is being displayed. The  
bottom light indicates the weld feed speed (WFS) is  
being displayed.  
ENGLISH OR METRIC SPEED  
DISPLAY UNITS  
Pressing both the Gas Purge key and Timer Selection  
key causes the speed display units to toggle between  
inches per minute (no decimal point displayed) or  
meters per minute (decimal point displayed). If the LED  
display is showing the voltmeter or one of the timer  
settings when these keys are pressed, the display will  
change to the weld speed to indicate the selected  
speed display units. See Figure B.1 for key locations.  
INCREASE ARROW. This key increases the setting  
of the parameter selected to be displayed, using the  
“Quick-Set” feature for fast and accurate setting.  
CIRCUIT PROTECTION  
DECREASE ARROW. This key decreases the setting  
of the parameter selected to be displayed, using the  
“Quick-Set” feature for fast and accurate setting.  
The LN-742 has solid-state overload protection of the  
wire drive motor. If the wire drive motor becomes  
overloaded for an extended period of time, the  
protection circuitry turns off the power source, wire  
feeder, and solenoid, then displays the error code E30  
on the LED display. This indicates the wire drive motor  
is overloaded, with the number indicating the time  
remaining in seconds before the unit will automatically  
reset. This number continues to decrement every  
second until it reaches zero. At that time the unit  
resets automatically and the previous display will  
return indicating that the unit is ready for operation.  
QUICK-SET FEATURE. This feature permits the  
arrow keys to control each display digit one at a time.  
The display digits blink in sequence from left to right.  
Pressing an arrow key immediately after a digit blinks  
alters that digit. Releasing the arrow key causes the  
left-to-right sequencing to resume.  
COLD INCH KEY. This key energizes the wire feeder  
to inch the wire forward, but does not energize the  
power source or solenoid valve.  
Over loads can result from: improper tip size, liner,  
drive rolls, or guide tubes; obstructions or bends in the  
gun cable; feeding wire that is larger than the rated  
capacity of the feeder; or any other factors that would  
impede normal wire feeding.  
GAS PURGE KEY. This key energizes the solenoid  
valve to purge any remaining gasses, but does not  
energize the wire feeder or power source.  
ACCELERATION SETTING  
DRIVE ROLL INSTALLATION  
Pressing both the Gas Purge key and the Function  
Selection key at the same time, on the keypad shown  
in Figure B.1, enables the acceleration setting display.  
The LED display will indicate “A-X” with “X” being a  
number from 1 (slowest) to 5 (fastest). This number is  
adjusted using the setting adjustment arrow keys. To  
exit the acceleration setting function, press both keys a  
second time, or press any other key except for the  
setting adjustment arrow keys.  
CHANGING DRIVE ROLLS FOR TWO-  
ROLL WIRE FEEDERS:  
To change drive rolls on a two-roll wire feeder, refer to  
Figure B.2 and perform the following steps:  
1. Turn off the welding power source.  
2. Rotate the latch knob on the quick release arm.  
LN-742 & LN-742H  
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B-4  
B-4  
OPERATION  
FIGURE B.2 – INSTALLING DRIVE ROLLS ON A TWO-ROLL FEEDER.  
CLAMPING  
COLLAR  
SPACER (IF REQUIRED)  
DRIVE  
ROLL  
HALVES  
OUTPUT  
SHAFT  
LARGE  
RADIUS  
GUIDE TUBE DETAIL  
OUTGOING  
GUIDE  
DRIVE  
ROLL  
TUBE  
OUTGOING  
GUIDE TUBE  
INSERT  
INCOMING  
GUIDE  
IDLE  
ROLL  
TUBE  
SMALL  
RADIUS  
LN-742 & LN-742H  
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B-5  
B-5  
OPERATION  
3. Remove the hex head screw and clamping collar.  
4. Loosen the thumb screws holding the guide tubes  
in place. Remove the incoming and outgoing  
guide tubes, if installed.  
Remove the drive roll from the shaft.  
4. The new roll to be installed is stamped for the size  
wire to be fed. An “A” after the size indicates  
aluminum wire. Remove the rolls from the kit and  
wipe them clean. Wipe the output shaft and locating  
shoulder clean.  
5. Remove the hex head screws and clamping  
collars from the output shafts. Remove the drive  
rolls and middle guide tube.  
6. The new rolls to be installed are stenciled with the  
wire size that will be fed. An “A” after the number  
indicates aluminum wire. Remove the rolls from  
the kit and wipe them clean. Wipe the output  
shafts and locating shoulders clean.  
5. Use the clamping collar and hex head screw to  
install the roll on the output shaft. Certain size drive  
rolls consist of two roll halves, and may contain a  
spacer. If the drive roll you are installing contains a  
spacer, the spacer fits between the two halves of  
the drive roll. Tighten the hex head screw.  
7. Install one roll onto the output shaft closest to the  
incoming side of the feeder clamping collar and  
hex head screw. Certain size drive rolls consist of  
two roll halves, and may contain a spacer. If the  
drive roll you are installing contains a spacer, the  
spacer fits between the two halves of the drive  
roll. Tighten the hex head screw.  
6. Back out the guide tube clamping screws.  
Remove the old guide tubes, if installed.  
7. Insert the longer guide tube into the rear hole and  
the other guide tube through the front hole. The  
fine wire chisel point end of the guide tube must  
have the larger radius end next to the drive roll.  
See Figure B.2. Push the guide tube back as far  
as it will go and tighten the clamping screw. Insert  
the incoming guide tube as far back as it will go  
and tighten the clamping screw. The clamping  
screws are dog points. When the guide tubes are  
properly installed these dog points will lock into  
the annular grooves in each of the guide tubes.  
8. Install the middle guide tube, but do not tighten at  
this time. When installing a 0.035” middle guide  
tube the larger radius should be aligned towards  
the drive roll. Slide the guide tube up against the  
installed drive roll.  
9. Install the second drive roll on the remaining shaft  
the same way as the first. Center the middle guide  
tube between the rolls and tighten the  
thumbscrews holding it in place.  
8. Set the idle roll pressure as detailed in the Idle  
Roll Pressure Setting procedure detailed later in  
this section.  
10. Close and latch both quick release levers.  
11. Slide the longer guide tube into the rear hole of  
the gearbox until it almost touches the drive roll  
and guide tube. Tighten the thumbscrew to hold it  
in place.  
CHANGING DRIVE ROLLS FOR FOUR-  
ROLL WIRE FEEDERS:  
To change drive rolls on a four-roll wire feeder, refer to  
Figure B.3 and perform the following steps:  
12. Install the outgoing guide tube into the front hole  
of the gearbox (through the conductor block) and  
tighten the thumb screw. The 0.035 in. outgoing  
guide tube should have the larger radius oriented  
toward the drive roll. For proper installation of the  
outgoing guide tube insert, refer to Figure B.3.  
1. Turn off welding power source.  
2. Remove the gun and cable from the conductor  
block on the feeder by loosening the hand screw  
and pulling the gun straight out of the block.  
13. Be certain that the guide tubes do not touch the  
drive rolls or idle rolls. If they do touch, readjust  
them and tighten in place.  
3. Open both quick release levers by moving the  
levers outward and pulling them toward you.  
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B-6  
B-6  
OPERATION  
FIGURE B.3 – INSTALLING DRIVE ROLLS ON A FOUR-ROLL FEEDER.  
CLAMPING  
COLLAR  
DRIVE  
ROLL  
HALVES  
SPACER  
(IF REQUIRED)  
OUTPUT  
SHAFT  
LARGE  
RADIUS  
GUIDE TUBE DETAIL  
OUTGOING  
GUIDE  
TUBE  
OUTGOING  
GUIDE TUBE  
INSERT  
MIDDLE  
GUIDE  
TUBE  
IDLE  
ROLL  
SMALL  
RADIUS  
LN-742 & LN-742H  
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B-7  
B-7  
OPERATION  
2. After outgoing pressure is set, determine how  
many turns away from full pressure the setting is.  
IDLE ROLL PRESSURE SETTING  
The idle roll pressure is set at the factory. Two-roll  
feeders are set with the pressure adjustment knob  
backed out two turns from full pressure, and four-roll  
feeders are set backed out three turns. This is an  
approximate setting. For small wire sizes and  
aluminum wire the optimum idle roll pressure varies  
with type of wire, surface condition, lubrication, and  
hardness. The optimum idle roll setting can be  
determined as follows:  
3. Set both idle roll tensions to this setting. Engage  
both idle rolls before welding. For most  
applications, best wire feeding will occur when  
both idle roll pressures are set the same.  
FIGURE B.4 – IDLE ROLL PRESSURE SETTING.  
Two-roll wire feeders:  
1. Press the end of the gun against a solid object  
that is electrically isolated from the welder output  
and press the trigger for several seconds.  
2. If the wire “birdnests”, jams, or breaks at the drive  
roll, the idle roll pressure is set too high. Back the  
pressure adjustment knob, Figure B.4, out 1/2  
turn. Run new wire through the gun and repeat  
step 1.  
3. If the only result is drive roll slippage, loosen the  
gun cable clamping screw on the conductor block  
and pull the gun cable forward about six inches.  
There should be a slight waviness in the exposed  
wire. If there is no waviness, the pressure is too  
low. Increase the pressure setting 1/4 turn. Lock  
the gun cable in place and repeat steps 1 and 2.  
Four-roll wire feeders:  
PRESSURE  
ADJUSTMENT  
KNOB  
1. Release the incoming idle roll and perform the  
pressure setting procedure for two roll feeders to  
set outgoing idle roll pressure.  
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B-8  
B-8  
OPERATION  
6) Set one of the Readi-Reel inside cage wires on the  
slot in the retaining spring tab.  
WIRE LOADING  
Loading a 22 to 30 Lb. (10 to 14 kg) Readi-Reel  
Package Using the Molded Plastic K363-P  
Readi-Reel Adapter:  
7) Lower the Readi-Reel to depress the retaining  
spring and align the other inside cage wires with  
the grooves in the molded adapter.  
The Spindle should be located in the LOWER mounting hole  
of the K1524-1 Universal Stand if used.  
8) Slide the cage all the way onto the adapter until  
the retaining spring "pops up" fully.  
1) Depress the Release Bar on the Retaining Collar and  
remove it from the spindle. NOTE: Earlier spindles  
used a threaded collar. See Figure B.5a or B.5b.  
WARNING  
Check to be sure the Retaining Spring has fully  
returned to the locking position and has SECURELY  
locked the Readi-Reel Cage in place. Retaining  
Spring must rest on the cage, not the welding elec-  
trode.  
2) Place the Adapter on the spindle.  
3) Re-install the Retaining Collar. Make sure that the  
Release Bar “pops up” and that the collar retainers  
fully engage the retaining groove on the spindle.  
___________________________________________  
9) To remove Readi-Reel from Adapter, depress  
retaining spring tab with thumb while pulling the  
Readi-Reel cage from the molded adapter with  
both hands. Do not remove adapter from spindle.  
4) Rotate the spindle and adapter so the retaining  
spring is at the 12 o'clock position.  
5) Position the Readi-Reel so that it will rotate in a  
direction when feeding so as to be de-reeled from  
the bottom of the coil.  
FIGURE B.5b (Retaining Collar)  
FIGURE B.5a (Threaded Locking Collar)  
2
IN. O.D. SPINDLE  
ADAPTER  
RETAINING SPRING  
BRAKE  
HOLDING  
PIN  
GROOVES  
READI-REEL  
INSIDE CAGE WIRES  
THREADED  
LOCKING  
COLLAR  
LN-742 & LN-742H  
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B-9  
B-9  
OPERATION  
TO MOUNT 10 TO 44 lb (4.5 to 20 kg) SPOOLS  
(12 in./300 mm DIAMETER) OR 13-14 lb (6 kg)  
INNERSHIELD COILS:  
2. While tightly holding the electrode, cut off the bent  
end and straighten the first six inches. Cut off the  
first inch. (If the electrode is not properly  
straightened, it may not feed or may not go into  
the outgoing guide tube, causing a “birdnest”.)  
The spindle should be located in the lower mounting  
hole of the K1524-1 Universal Stand if used.  
3. Insert the free end through the incoming guide  
tube.  
[For 8 in. (200 mm) spools, a K468 spindle adapter  
must first be slipped onto the spindle.]  
4. Press the cold inch key or gun trigger and push  
the electrode into the drive roll.  
[For 13 to 14 lb (6 kg) Innershield coils, a K435 Coil  
Adapter must be used.]  
WARNING  
1. Depress the Release Bar on the Retaining Collar  
and remove it from the spindle. NOTE: Earlier  
spindles used a threaded collar. See Figure B.5a or  
B.5b.  
ELECTRIC SHOCK  
can kill.  
• Do not touch electrically live parts  
such as output terminals or  
internal wiring.  
2. Place the spool on the spindle, making certain  
the spindle brake pin enters one of the holes in  
the backside of the spool. Be certain the wire  
comes off the reel in a direction so as to de-reel  
from the bottom of the coil.  
• When inching with the gun  
trigger, electrode and drive  
mechanism are “hot” to work and  
ground and could remain “hot” for  
several seconds after the gun  
trigger is released.  
3. Re-install the Retaining Collar. Make sure that  
the Release Bar “pops up” and that the collar  
retainers fully engage the retaining groove on the  
spindle.  
------------------------------------------------------------------------  
5. Inch the electrode through the gun.  
ELECTRODE  
ADJUSTMENT  
FEEDING  
AND  
BRAKE  
6. Adjust the brake tension with the thumbscrew on  
the spindle hub until the reel turns freely but with  
little or no overrun when wire feeding is stopped.  
Do not overtighten.  
1. Turn the Readi-Reel or spool until the free end of  
the electrode is accessible.  
LN-742 & LN-742H  
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B-10  
B-10  
OPERATION  
WIRE REEL LOADING – 50 AND 60 LB  
COILS (K303 OR K376 WIRE REEL STAND)  
CAUTION  
Always be sure the free end of the coil is securely held  
while the tie wires are being cut and until the wire is  
feeding through the drive rolls. Failure to do this will  
result in “back lashing” of the coil, which may tangle the  
wire. A tangled coil will not feed. It must be untangled  
or discarded.  
ADJUSTABLE WIRE REEL BRAKE  
The mount for standard 50 and 60 pound electrode  
coils includes a two-position brake assembly.  
Generally the brake should be at the inner position  
(nearest to the wire reel shaft) for wire feed speeds  
below 400 in./min (10 m/min). It should be at the outer  
position for the faster wire speeds often used when  
feeding smaller diameter electrode.  
------------------------------------------------------------------------  
8. Cut and remove only the tie wire holding the free  
end of the coil. Insert the free end into one of the  
holes in the cover and secure it by bending it  
back. Cut and remove the remaining tie wires.  
To adjust the brake position, remove the wire reel. Pull  
the cotter pin that holds the brake shoe to the arm,  
move the shoe and replace the cotter pin. Do not bend  
the cotter pin - it is held in place by a friction fit.  
9. Replace the reel on the wire feeder. Grasp the  
shaft knob, pull it out and swing it across the reel  
hub, locking the reel in place.  
TO MOUNT A 50 OR 60 LB COIL:  
FIGURE B.6 – LOADING A 50 OR 60 LB COIL.  
1. To remove the wire reel from its shaft, grasp the  
spring loaded knob and pull out. This straightens  
the knob so it seats into the shaft when released.  
Remove the reel.  
SPINNER  
NUT  
COVER  
PLATE  
2. Lay the reel flat on the floor. Loosen the spinner  
nut and remove the cover plate. See Figure B.6.  
3. Place the coil of electrode on the reel so it  
unwinds as the reel rotates clockwise. DO NOT  
cut the tie wires at this time.  
SLOTS  
4. Be sure the coil is placed so the spring loaded  
arms will not interfere with the later removal of the  
coil tie wires.  
CARDBOARD  
COIL  
LINER  
5. When loading 0.030 to 0.045” electrode, be  
certain the coil is placed on the reel so the spring  
loaded arms are at the center of the slots in the  
cardboard coil liner. This provides the positive  
compression of the coil sides needed for trouble-  
free wire feeding.  
COIL  
TIE WIRE  
6. Put the cover plate on the reel so the four arms of  
the cover plate straddle and are in line with the  
spring loaded arms of the reel.  
REEL  
SPRING  
LOADED  
ARM  
7. Tighten the cover as much as possible by hand.  
DO NOT hammer on the spinner nut arms.  
LN-742 & LN-742H  
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B-11  
B-11  
OPERATION  
FIGURE B.7 – K1504-1 COIL REEL.  
WIRE REEL LOADING – 50 AND 60 LB  
COILS (K1524-1 UNIVERSAL WIRE REEL  
STAND)  
SPINNER NUT  
TO MOUNT A 50 to 60 lb (22.7 to 27.2 kg) COIL:  
(USING K1504-1 COIL REEL) (FOR 50 to 60 lb  
READI-REELS A K438 READI-REEL ADAPTER  
MUST BE USED.)  
COVER  
PLATE  
The spindle should be located in the UPPER mount-  
ing hole.  
SLOTS  
1. With the K-1504-1 Coil Reel mounted on the 2 in.  
(51 mm) spindle (or with reel laying flat on the  
floor) loosen the spinner nut and remove the reel  
cover. See Figure B.7.  
CARDBOARD  
COIL LINER  
2. Before cutting the tie wires, place the coil of elec-  
trode on the reel so it unwinds from the bottom  
as the reel rotates.  
COIL  
3. Tighten the spinner nut against the reel cover as  
much as possible by hand, using the reel cover  
spokes for leverage. DO NOT hammer on the  
spinner nut arms.  
TIE WIRE  
SPRING  
LOADED ARM  
4. Cut and remove only the tie wire holding the free  
end of the coil. Hook the free end around the rim  
of the reel cover and wrap it around to secure.  
Cut and remove the retaining tie wires.  
REEL  
CAUTION  
Always be sure the free end of the coil is securely  
held while the tie wires are being cut and until the wire  
is feeding through the drive rolls. Failure to do this will  
result in “backlash” of the coil, which may tangle the  
wire. A tangled coil will not feed, so it must either be  
untangled or discarded.  
____________________________________  
5. Be sure the coil is engaged with the spindle  
brake pin and the Release Bar and Retaining  
Collar “pops up” and that the collar retainers fully  
engage the retaining groove on the spindle.  
LN-742 & LN-742H  
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B-12  
B-12  
OPERATION  
9. Position the electrode over the joint. The end of  
the electrode may be lightly touching the work.  
MAKING A WELD  
1. Use only constant voltage power type sources. If  
using a multiple process power source, be sure it  
is set for constant voltage output per instructions  
in the manual for the power source.  
10. Lower your welding helmet. Close the gun trigger  
and begin welding. Hold the gun so the contact tip  
to work distance gives the correct electrical  
stickout as required for the procedure being used.  
2. Set the power source polarity switch or properly  
connect the electrodes and work leads for the  
correct electrode polarity.  
11. To stop welding, release the gun trigger and then  
pull the gun away from the work after the arc goes  
out.  
3. Set the voltage using the control on the power  
source or, if used, the optional K589-1 Remote Kit  
or K857 Remote Voltage Control. Set the open  
circuit voltage to approximately 2 volts higher  
than the desired procedure voltage. The final  
setting must be made according to the arc voltage  
while welding.  
WIRE REEL CHANGING  
At the end of a coil, remove the last of the old electrode  
from the conductor cable. Either pull it out at the  
nozzle, or use the following procedure:  
1. Cut off the end of the electrode at the gun end. Do  
not break it off by hand. Breaking by hand puts a  
slight bend in the wire, making it difficult to pull it  
back through the nozzle.  
4. Use the Mode Selection key to set the desired  
operating mode.  
5. Use the Function Selection key and Selection  
Setting arrow keys to set the desired Inch and  
Weld Feed speeds.  
2. Uncouple the gun conductor cable from the  
conductor block on the wire feeder drive unit and  
lay the gun cable out straight.  
6. Use the Time Selection key and Selection Setting  
arrow keys to set the desired timers.  
3. Using pliers, grip the wire and pull it out of the  
cable from the connector end.  
7. Inch the electrode through the gun and cable. For  
solid wire, cut the electrode within approximately  
3/8 in. of the end of the contact tip. If using cored  
wire, cut the electrode within 3/4 in. of the  
extension guide.  
4. After the electrode has been removed, connect  
the gun conductor back to the wire feeder.  
5. Load a new reel of electrode per the instructions  
for the specific reel type given previously in this  
section.  
8. Connect the work cable to the metal to be welded.  
The work cable must make good electrical  
contact with the work. The work must also be  
grounded.  
WARNING  
When using an open arc process, it is necessary to  
use correct eye, head, and body protection.  
------------------------------------------------------------------------  
LN-742 & LN-742H  
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C-1  
C-1  
ACCESSORIES  
GENERAL  
The following is a list of the accessories that can be  
used with the LN-742 wire feeder.  
A detailed description of each item is given later in this  
section.  
TABLE C.1 – LN-742 ACCESSORIES.  
Product Number  
K163  
Name  
Undercarriage  
K178-1  
K589-1  
K590-1  
K590-2  
K857  
Mounting Platform  
Remote Control Kit  
Water Solenoid Kit  
Water Connection Kit  
Remote Voltage Control Kit  
Magnetic Separator  
Flux Screen  
K58  
K310  
K320  
Flux Tank  
K619  
Input Cable - 350 Amps  
K112  
Submerged Arc Welding Gun - 500 Amps  
Innershield Welding Gun - 400 Amps  
Innershield Welding Gun - 350 Amps  
Magnum GMA Welding Gun - 200 Amps  
Magnum GMA Welding Gun - 300 Amps  
Magnum GMA Welding Gun - 400 Amps  
Spindle  
K115  
K126  
K470  
K471  
K497  
K162H  
K363P  
K376 and 303  
K1524-1  
K1504-1  
K1551-1  
K1556-1  
K1557-1  
K1819-25  
K1819-50  
K1819-75  
K1819-100  
K377  
22 to 30 lb Readi-Reel Adapter  
50 to 60 lb Wire Reel Mounting Stands  
Universal Wire Reel Stand - 2” Spindle  
60 lb Coil Adapter for K1524-1 Stand  
Insulated Lift Bail for K1524-1 Stand  
Caster Kit for K1524-1 Stand  
Swivel Platform for K1524-1 Stand  
Control Cable Assembly 25 Ft.  
Control Cable Assembly 50 Ft.  
Control Cable Assembly 75 Ft.  
Control Cable Assembly 100 Ft.  
Small Mounting Stand for Readi-Reel Coils and 22 to 30 lb Spindle with 2 in. O.D.  
Small Mounting Stand for 13 to 14 lb Innershield Coils  
Spindle Adapter for 14 lb Coils  
K378  
K435  
K438  
50 to 60 lb Readi-Reel Adapter  
K445  
Mounting Stand for Readi-Reel Coils and 50 to 60 lb Spindle with 2 in. O.D.  
Spindle Adapter for 8 in. O.D. Spools  
Wire Reel Dust Shield Door for K303 and K376  
Wire Reel Dust Shield for K376 50 to 60 lb Wire Reel Mounting Stand  
K468  
M11514  
S14543  
LN-742 & LN-742H  
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C-2  
C-2  
ACCESSORIES  
K857 can be installed on the LN-742 when it is used  
with newer Lincoln power sources that are equipped  
with a 6-socket ms-type receptacle or K864 14-pin  
connector adapter for connection of the plug on the 28  
ft (8.5 m) control cable of the K857. See the  
instructions (S19103) included with the kit.  
K163 UNDERCARRIAGE  
The undercarriage includes casters, wheels, a handle,  
and related hardware. Casters are mounted at the front  
and wheels at the rear of the platform. The handle is  
bolted to the front of the platform so the wire feeder  
can be tilted back and wheeled like a two-wheel truck.  
Installation sheet M13424 is provided with the  
undercarriage.  
FLUX SYSTEM COMPONENTS  
The flux system is available to permit the LN-742 to be  
used for submerged arc welding. It is comprised of the  
components described below.  
K178-1 MOUNTING PLATFORM  
This is a turntable type platform for mounting the LN-  
742 to the top of Idealarc power sources. Bolt the  
platform to the lift bail per the instructions (M16260)  
supplied with the platform.  
K58 MAGNETIC SEPARATOR  
The K58 is a permanent magnet type separator  
designed to fit the top of the standard fill funnel of the  
continuous flux feeding system.  
K589-1 REMOTE  
CONTROL KIT  
The purpose of the separator is to remove magnetic  
materials such as mill scale and any other extraneous  
magnetic materials which may have been recovered  
along with the flux to be processed.  
Provides remote potentiometer control of weld speed  
and arc voltage up to 16.4 ft (5.0 m) from the wire  
feeder. Power source must have remote control  
capability. (K856 Power Source Remote Kit required  
for CV-300/400-I, and smaller CV- Model machines  
below Code 9900.) Install K589-1 Kit per S20520  
installation instructions provided with the kit.  
It is important to remove these magnetic particles from  
the flux which is to be used in the continuous flux  
feeding systems. If the magnetic material is not  
removed it will gather around the nozzle of the gun and  
impede or shut off the flux flow when making relatively  
long welds or welding continuously. The magnetic  
particles can also cause porosity in the weld.  
K590-1 WATER  
SOLENOID KIT  
K310 FLUX SCREEN  
Includes a solenoid valve already attached to a  
mounting bracket and supply connection manifold  
assembly for easy installation on the upper rear panel  
of the LN-742 case. Also includes water-cooled gun  
tube fittings and self-sealing outlet and inlet quick-  
connectors for mounting to the front of the LN-742  
case.  
The unit was designed to fit the top of either the  
standard fill funnel or a K58 magnetic separator. The  
unit has a steel screen with 0.065 to 0.075 in. openings  
and an air vibrator attached to the frame. The vibrator  
can be used with air line pressures ranging from 20  
through 100 psi.  
K590-2 WATER  
CONNECTION KIT  
For ease of handling, the user should connect the  
incoming air line to the 1/8 in. pipe elbow with the aid  
of a quick disconnect type air coupling.  
This kit is the same as the K590-1 except that it does  
not include the solenoid for water coolers requiring  
continuous flow.  
It is very important that reclaimed flux to be used in the  
continuous flux feeding system be passed through the  
K310 screen or its equivalent.  
K857 REMOTE VOLTAGE  
CONTROL KIT  
Installs on the side of the LN-742 control box cover and  
gives voltage control at the wire feeder.  
LN-742 & LN-742H  
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C-3  
C-3  
ACCESSORIES  
K320 FLUX TANK  
WELDING GUNS  
Either turn off the incoming air line or remove the quick  
disconnect if one has been installed. Slightly loosen  
the tank cap and let the air in the tank escape in the  
holes in the side of the cap. After pressure has been  
released, remove the cap from the tank. Using the  
funnel provided, put 100 pounds of flux in the tank. It is  
very important that only new or properly reclaimed flux  
be put in the tank. Coarse particles and/or magnetic  
particles will stop the flux feeding process. New Lincoln  
flux is properly screened at the factory. All reclaimed  
flux must be separately screened through a vibrating  
screen with 0.065 in. to 0.075 in. openings and be put  
through a magnetic separator. The K310 vibrated  
screen and K58 magnetic separator are available for  
this purpose. The screen in the funnel supplied with the  
tank has much larger openings and its only purpose is  
to keep paper and slag out of the tank.  
Welding guns can be broken down into groups,  
according to the type of welding that is to be  
accomplished. Select the appropriate welding gun from  
the following weld-type groups.  
INNERSHIELD GUNS  
K122. This submerged arc gun and its cable assem-  
blies are rated 500 amps, 60% duty cycle.  
K115. This Innershield gun and its cable assemblies  
are rated at 450 amps, 60% duty cycle. Maximum wire  
size for LN-742 models is 5/64 in. (2.0 mm).  
K126. This Innershield gun and its cable assemblies  
are rated at 350 amps, 60% duty cycle. Maximum wire  
size for LN-742 models is 5/64 in. (2.0 mm).  
There will always be a small amount of air and possible  
drops of water coming out of the end of the tube coiled  
under the tank. This is an automatic disposal system in  
case the plant air has water and dirt in it.  
NOTE: The K115 and K126 are not recommended for  
LN-742H models.  
TM  
NOTE: Linconditioner guns are recommended for  
locations where smoke accumulation is a problem and  
conventional exhaust systems are ineffective. The  
available smoke removal type Innershield guns and  
vacuum units can be used in these locations.  
Instructions are shipped with the equipment.  
POWER INPUT CABLES  
A variety of power input cable assemblies are avail-  
able for various current ratings and power source con-  
nection types. All provide a polarized control cable  
plug and a lugged electrode cable for connection to  
the wire feeder.  
K1819-[ ] CONTROL CABLES  
These control cables connect the wire feeder to the  
power source.The wire feeder end is an 8 pin anphe-  
nol and the power source end is a 14 pin amphenol.  
The control cable supplies 42VAC from the welding  
power source to the feeder. It also carries a lead for  
the work voltage and sends signals for the gun trigger  
and remote voltage potentiometer. See connection  
diagram of wire feeder to power source in the  
“Installation Section”.  
K1817-[ ] CONTROL CABLE EXTENSIONS  
The control cable extensions are used to lengthen the  
control cable. The extensions have a 14 pin amphenol  
on one end that connects to the K1819-[ ] cable and  
the other end has a 14 pin amphenol that connects to  
the welding power source. Do not exceed more than  
100 Ft. (31m) of total control length. See connec-  
tion diagram of wire feeder to power source in the  
“Installation Section”.  
LN-742 & LN-742H  
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C-4  
C-4  
ACCESSORIES  
SUBMERGED ARC GUNS  
UNIVERSAL WIRE REEL STAND (K1524-1)  
Includes a 2" (51mm) O.D. Spindle with adjustable  
brake and two locations for mounting the spindle to  
allow for the mounting of 50 - 60lb, 10 - 30 lb, 13 -  
14lb, and 8" O.D. coils with proper spindle adapters.  
(See OPERATION section) Capable of being mount-  
ed on the top of a suitable power source or surface  
without the need for any other mounting kit. Optional  
features available for this stand include:  
The K112 gun and cable assembly is recommended  
for welding with 1/16 in. solid steel electrode at up to  
500 amps. Gun cable length is 15 feet.  
GMAW GUNS  
An expanding line of Magnum GMA gun and cable  
assemblies are available to allow welding with solid  
and cored electrodes using the GMAW process. See  
the appropriate Magnum literature for descriptions of  
the 200-400 ampere air cooled guns and cables that  
are available. Gun cable lengths range from 10 to 25 ft.  
(3.0 to 7.5 m) and feed electrode sizes 0.025 in. to 5/64  
in. (0.6 to 2.0 mm).  
• K1555-1 insulated lift bale  
• K1556-1 caster kit  
• K1557-1 swivel platform.  
60 LB. (27.2 KG) COIL ADAPTER (K1504-1)  
Permits 50-60 lb. (22.7-27.2 Kg) coils to be mounted  
to a 2" (51mm) spindle.  
SPINDLES, STANDS, AND  
ADAPTERS  
K1551-1 INSULATED LIFT BALE: Provides a  
bolt on lift bale with an electrically insulated lift hook.  
There are a variety of spindles and wire reel adapters  
available for use with the LN-742. Select the desired  
setup according to your specific welding needs.  
K1556-1 CASTER KIT: Comes with 4 light duty  
2" O.D. casters which mount in place of the rubber  
feet on the wire stand. Use in light duty applications  
where portability is required. Can be used in combi-  
nation with the K1557-1 swivel platform.  
K162H SPINDLE  
The K162H spindle is used for mounting Readi-Reels  
and 2 in. I.D. spools with a 60 lb capacity on a K303 or  
K376 Wire Reel Stand. When used with Readi-Reels,  
a Readi-Reel Adapter is required. For 8 in. O.D.  
spools, a K468 Spindle Adapter is available.  
K1557-1 SWIVEL PLATFORM: Allows for the  
mounting of the wire feeder reel stand assembly on  
top of a suitable power source if the need for the wire  
feeder reel stand assembly to swivel is desired. Also  
has mounting holes in the base feet for mounting to  
any surface that it can be fastened to. Comes with a  
rotating tool tray to hold gun tips, guide tubes, drive  
rolls, etc. Will work in combination with the K1556-1  
caster kit.  
K363P 22 TO 30 LB READI-REEL  
ADAPTER  
Adapts Lincoln Readi-Reel coils of 22 and 33 lb (10  
and 14 kg) to a 2 in. (51 mm) spindle. Durable, molded  
plastic, one piece construction. Designed for easy  
loading -- adapter remains on spindle for quick  
changeover. (Included with K377.)  
K376 AND K303 50 TO 60 LB WIRE REEL  
MOUNTING STANDS  
The K376 50 to 60 lb Wire Reel Mounting Stand and  
the K303 Wire Reel Mounting Stand are the same with  
the exception that the K303 stand includes a dust  
shield. The assembly includes a framework to which is  
attached the 50 to 60 lb wire reel, a mounting spindle,  
a lift bale, and a cable clamp for fastening the input  
cable assembly. It is easily mounted to the basic wire  
feed unit by following the Attaching the Wire Reel  
Stand procedure at the end of this section.  
LN-742 & LN-742H  
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C-5  
C-5  
ACCESSORIES  
K377 SMALL MOUNTING STAND FOR  
READI-REEL COILS AND 22 TO 30 LB  
SPINDLE WITH 2 IN. I.D.  
K468 SPINDLE ADAPTER FOR  
8 IN. O.D. SPOOLS  
Permits 8 in. (203 mm) O.D. spools to be mounted on  
2 in. (51 mm) O.D. spindles. For K377 and K445, or  
K303 and K376 with optional K162H adapter.  
This assembly includes a wire reel spindle (similar to  
the K162 spindle) attached to a small frame. The unit  
is supplied with the K363 Readi-Reel Adapter for using  
the Lincoln “Readi-Reel Electrode Coils”. Without the  
adapter the unit is capable of handling spools with a  
2 in. I.D., a 12 in. maximum O.D., and a 4 in. width. For  
spools with an 8 in. O.D., a K468 spindle adapter is  
available. The spindle has an adjustable braking  
system. See Attaching the Wire Reel Stand  
procedure at the end of this section for installation  
procedures.  
M11514 WIRE REEL DUST SHIELD DOOR  
FOR K303 AND K376  
In extremely dusty and dirty locations this door kit can  
be added to those units having the dust shield kit  
(S14543). This door kit includes a hinged door and  
sliding bottom seal. When these parts are attached to  
the reel support per the instructions included, the unit  
becomes a completely enclosed housing. Order part  
no. M11514.  
K378 SMALL MOUNTING STAND FOR  
13 TO 14 LB INNERSHIELD COILS  
S14543 WIRE REEL DUST SHIELD FOR  
K376 50 TO 60 LB WIRE REEL MOUNTING  
STAND  
This assembly includes the same smaller frame as  
used in the K377 and the fully enclosed canister  
system for dereeling of the 14 lb coil. This system has  
a fixed brake for the 14 lb coil. See Attaching the Wire  
Reel Stand Procedure at the end of this section for  
installation procedures.  
A shield is available to cover the wire and reel to  
protect the wire from falling dirt and dust. Order part  
no. S14543. Instructions are provided with the kit.  
K435 SPINDLE ADAPTER FOR  
14 LB COILS  
ATTACHING THE WIRE  
REEL STAND  
The mounting hardware for mounting the stands is  
included with the LN-742. Screws and washers are  
inserted in their respective mounting holes. To  
connect:  
Permits 14 lb (6 kg) Innershield coils to be mounted on  
2 in. (51 mm) O.D. spindles. For K377 and K445, or  
K303 and K376 with optional K162H adapter.  
K438 50 TO 60 LB READI-REEL ADAPTER  
Adapts Lincoln Readi-Reel coils of 50 to 60 lb (22.7 to  
27.7 kg) to a 2 in. (51 mm) spindle. (Included with  
K445.)  
1. Remove the three 3/8 in. hex head bolts from the  
back of the wire feed unit.  
2. Place the wire reel mounting stand mounting  
bracket in position against the back of the wire  
feed unit.  
K445 MOUNTING STAND FOR READI-  
REEL COILS AND 50 TO 60 LB SPINDLE  
WITH 2 IN. O.D.  
3. Replace and tighten the hex head bolts. The long  
screw and plain washer go into the top hole.  
50 to 60 lb (22.7 to 27.7 kg) Readi-Reel mounting  
stand. This assembly includes framework that a 2 in.  
(51 mm) O.D. spindle with adjustable brake and 50 to  
60 lb (22.7 to 27.7 kg) (K438) Readi-Reel adapter.  
Includes a lift bail and cable clamp for fastening the  
input cable assembly. Does not include a dust shield.  
A dust shield that covers the wire reel and protects the  
wire from falling dirt and dust is available for this unit.  
Order part number S14543. This unit will accept the  
M11514 door kit (see K303) but only if already  
equipped with optional dust shield (S14543).  
LN-742 & LN-742H  
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C-6  
C-6  
ACCESSORIES  
DRIVE ROLL KITS  
Table C-2 lists the appropriate drive roll kits for each  
type of wire used.  
TABLE C.2 – DRIVE ROLL KIT NUMBERS.  
2-Roll  
4-Roll  
Steel Wire Sizes  
0.068-3/32 in. (1.7-2.4 mm) Cored  
1/16 in. (1.6 mm) Cored or Solid  
0.045-0.052 in. (1.2-1.3 mm) Solid  
0.045-0.052 in. (1.2-1.3 mm) Cored  
0.035 in. (0.9 mm) Solid  
0.035 in. (0.9 mm) Cored  
0.030 in. (0.8 mm) Solid  
0.023-0.025 in. (0.6 mm) Solid  
Aluminum Wire Sizes  
KP653-3/32C  
KP653-1/16  
KP653-052S  
KP653-052C  
KP653-035S  
KP653-035C  
KP653-030S  
KP653-025S  
KP655-3/32C  
KP655-1/16  
KP655-052S  
KP655-052C  
KP655-035S  
KP655-035C  
KP655-030S  
KP655-025S  
1/16 in. (1.6 mm)  
3/64 in. (1.2 mm)  
0.035 in. (0.9 mm)  
KP654-1/16A  
KP654-3/64A  
KP654-035A  
KP656-1/16A  
KP656-3/64A  
KP656-035A  
LN-742 & LN-742H  
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D-1  
D-1  
MAINTENANCE  
No routine maintenance is required for Readi-Reels  
and 10 to 30 lb spools. Do not lubricate the 2 in.  
spindles.  
ROUTINE MAINTENANCE  
DRIVE ROLLS AND GUIDE TUBES  
PERIODIC MAINTENANCE  
After feeding every coil of wire, inspect the drive roll  
section. Clean the assembly as necessary. Do not use  
solvent to clean the drive roll assembly as it may wash  
the lubricant out of the bearings. The drive rolls and  
guide tubes are stamped with the wire sizes they will  
feed. If a wire size other than that stamped on the rolls  
is to be used, the rolls and guide tubes must be  
changed.  
WIRE DRIVE MOTOR AND GEARBOX  
Every year inspect the gearbox and coat the gear  
teeth with a moly-disulfide filled grease. Do not use  
graphite grease.  
Every six months check the motor brushes. Replace  
them if they are less than 1/4 in. long.  
The drive rolls for 0.045 and 0.052 cored electrode  
and 1/16, 0.068, 5/64, 3/32, and 7/64 electrode have  
a double set of teeth so they can be reversed for  
additional life. Drive rolls for 0.023 through 0.052 solid  
electrodes have no teeth.  
GUN AND CABLE MAINTENANCE  
For instructions on periodic maintenance for the  
welding gun and cables, refer to the instructions  
included with your specific model of welding gun.  
Refer to the instructions in Section B, Operation for  
installation of drive rolls.  
WIRE REEL MOUNTING  
To prolong the life of the reel shaft on the 50 to 60 lb  
coils, periodically coat it with a thin layer of grease. No  
maintenance to the two position brake is required. If  
the brake shoe wears through to metal, replace the  
brake assembly.  
LN-742 & LN-742H  
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E-1  
E-1  
TROUBLESHOOTING  
HOW TO USE TROUBLESHOOTING GUIDE  
WARNING  
Service and Repair should only be performed by 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 malfunctions.  
Simply follow the three-step procedure listed below.  
Step 3. RECOMMENDED COURSE OF ACTION  
This column provides a course of action for the  
Possible Cause, generally it states to contact your  
local Lincoln Authorized Field Service Facility.  
Step 1. LOCATE PROBLEM (SYMPTOM).  
Look under the column labeled “PROBLEM (SYMP-  
TOMS)”. This column describes possible symptoms  
that the machine may exhibit. Find the listing that  
best describes the symptom that the machine is  
exhibiting.  
If you do not understand or are unable to perform the  
Recommended Course of Action safely, contact your  
local Lincoln Authorized Field Service Facility.  
Step 2. POSSIBLE CAUSE.  
The second column labeled “POSSIBLE CAUSE” lists  
the obvious external possibilities that may contribute  
to the machine symptom.  
WARNING  
ELECTRIC SHOCK can kill.  
• Do not touch electrically live parts such as  
internal wiring.  
• Only qualified personnel should install, use or ser-  
vice this equipment.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your  
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.  
LN-742 & LN-742H  
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E-2  
E-2  
TROUBLESHOOTING  
Observe all Safety Guidelines detailed throughout this manual  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE  
CAUSE  
RECOMMENDED  
COURSE OF ACTION  
The display is blank. No wire feed 1. Make sure the control cable is  
when the gun trigger is activated.  
connected to the welding power  
source correctly.  
2. Make sure the welding power  
source is turned on and func-  
tioning properly.  
3. Check the 42 VAC fuse or cir-  
cuit breaker in the welding  
power source.  
If all recommended possible areas of  
misadjustment have been checked  
and the problem persists, Contact  
your local Lincoln Authorized  
Field Service Facility.  
No wire feed when the gun trigger 1. Check or replace the gun trigger  
is activated. The solenoid does not  
function. No arc voltage present.  
switch.  
The display board indicates the 2. Check the gun trigger recepta-  
LN-742 has input power applied.  
cle. Check for loose or faulty  
connections.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your  
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.  
LN-742 & LN-742H  
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E-3  
E-3  
TROUBLESHOOTING  
Observe all Safety Guidelines detailed throughout this manual  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE  
CAUSE  
RECOMMENDED  
COURSE OF ACTION  
When the gun trigger is activated 1. Make sure the welding power  
the wire feed motor runs and the  
solenoid functions but no arc volt-  
age is present.  
source is functioning properly.  
Disconnect the control cable  
from the Lincoln power source.  
Place a jumper across sockets  
C and D of the 14 pin amphenol  
plug at the power source. Open  
circuit voltage should be pre-  
sent at the welder output termi-  
nals. If no voltage is present at  
the output terminals the power  
source is faulty.  
2. The control cable may be faulty.  
Check leads #2 and #4 (pins C  
and D) for continuity (zero  
ohms).  
3. The welding cables may me  
faulty. Check for loose or faulty  
connections.  
4. The gun may be faulty. Check  
or replace.  
If all recommended possible areas of  
misadjustment have been checked  
and the problem persists, Contact  
your local Lincoln Authorized  
Field Service Facility.  
The wire feeds when the gun trig- 1. Check for loose or faulty con-  
ger is activated but there is no con-  
trol of the wire feed speed.  
nections between the tach and  
the control board plug J3.  
The wire feed speed does not 1. The inch and weld speeds may  
change when welding current  
begins to flow.  
be set to the same value.  
2. If the display shows the ----  
symbol the inch speed has  
been disabled. To enable the  
inch speed press the increase  
arrow key.  
3. Check plug J2 on the control  
board for loose or faulty con-  
nections.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your  
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.  
LN-742 & LN-742H  
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E-4  
E-4  
TROUBLESHOOTING  
Observe all Safety Guidelines detailed throughout this manual  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE  
CAUSE  
RECOMMENDED  
COURSE OF ACTION  
The LN-742 voltmeter does not 1. Make sure the polarity switch on  
function or read correctly when the  
actual arc voltage is present. The  
wire feeder is feeding wire correct-  
ly.  
the Lincoln welding power  
source is in the correct position  
for the welding process.  
2. Check or replace the control  
cable. Check the continuity  
(zero ohms) of leads #21 and  
#67.  
The LN-742 shuts down while 1. Check for mechanical restric-  
welding and the HXX symbol  
appears on the display.  
tions in the wire feed path.  
If all recommended possible areas of  
misadjustment have been checked  
and the problem persists, Contact  
your local Lincoln Authorized  
Field Service Facility.  
The display and/or indicator lights 1. Make sure the control cable is  
do not change when the arrow or  
select keys are pressed.  
connected to the welding power  
source correctly.  
2. Check the 42 VAC fuse or cir-  
cuit breaker in the welding  
power source.  
The arrow keys do not change the 1. If a remote control unit is con-  
welding wire feed speed.  
nected to the LN-742 the arrow  
keys will not change welding  
wire feed speed. Use the WFS  
pot on the remote control unit or  
disconnect the remote control  
unit and use the arrow keys.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your  
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.  
LN-742 & LN-742H  
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E-5  
E-5  
TROUBLESHOOTING  
Observe all Safety Guidelines detailed throughout this manual  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE  
CAUSE  
RECOMMENDED  
COURSE OF ACTION  
The purge key does not activate 1. Contact your local Lincoln  
the gas solenoid. The solenoid  
does activate when the gun trigger  
is pulled.  
Authorized Field Service  
Facility.  
The gas solenoid does not activate 1. Check plug J6, located on the  
either when the purge key is  
pressed or when the gun trigger is  
pulled.  
control board for loose or faulty  
connections.  
The cold inch key does not activate 1. Contact your local Lincoln  
the wire feed motor. The wire feed  
motor operates normally when the  
gun trigger is pulled.  
Authorized Field Service  
Facility.  
The HI symbol appears on the dis- 1. If the arc voltage is greater than  
play when the voltmeter function is  
selected.  
44 VDC, this is a normal condi-  
tion. The voltmeter only reads  
0-44 VDC.  
If all recommended possible areas of  
misadjustment have been checked  
and the problem persists, Contact  
your local Lincoln Authorized  
Field Service Facility.  
The Er symbol appears on the dis- 1. This is an EPROM error. The  
play.  
parameter recalled at power-up  
is out of range. Press any key  
to reset unit. Check all weld  
settings before proceeding with  
weld.  
The EXX appears on the display.  
(XX is some number from 1 to 10.)  
1. Remove input power to the  
feeder (42 VAC). Wait 5 sec-  
onds. The symbol should not  
reappear when power is  
returned.  
The EP symbol appears on the  
display.  
1. Remove input power to the  
feeder (42 VAC). Wait 5 sec-  
onds. The symbol should not  
reappear when power is  
returned.  
The uP symbol appears on the dis- 1. Remove input power to the  
play. (Microprocessor RAM error.)  
feeder (42 VAC). Wait 5 sec-  
onds. The symbol should not  
reappear when power is  
returned.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your  
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.  
LN-742 & LN-742H  
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E-6  
E-6  
TROUBLESHOOTING  
Observe all Safety Guidelines detailed throughout this manual  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE  
CAUSE  
RECOMMENDED  
COURSE OF ACTION  
The wire is feeding rough or not 1. Check for mechanical restric-  
feeding. The drive rolls are turn-  
ing.  
tions in the wire feeding path.  
Check the gun and gun compo-  
nents.  
2. Check the drive roll position and  
idle roll pressure.  
3. The electrode may be dirty or  
rusty.  
4. Check for the correct gun liner,  
tip, and guide tubes.  
If all recommended possible areas of  
misadjustment have been checked  
and the problem persists, Contact  
your local Lincoln Authorized  
Field Service Facility.  
The drive rolls do not turn when the 1. Check plug J5 on the control  
gun trigger is pressed. The gas  
solenoid activates and arc voltage  
is present.  
board for loose or faulty con-  
nections.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your  
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.  
LN-742 & LN-742H  
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E-7  
E-7  
TROUBLESHOOTING  
Observe all Safety Guidelines detailed throughout this manual  
PROBLEMS  
(SYMPTOMS)  
POSSIBLE  
CAUSE  
RECOMMENDED  
COURSE OF ACTION  
The welding arc is variable or 1. Check the welding cables for  
“hunting”.  
loose or faulty connections.  
2. Make sure the wire feed speed,  
voltage, polarity and shielding  
gas are correct for the process  
being used.  
3. Check for mechanical restric-  
tions in the wire feed path.  
4. Make sure the welding power  
source is functioning properly.  
If all recommended possible areas of  
misadjustment have been checked  
and the problem persists, Contact  
your local Lincoln Authorized  
Field Service Facility.  
Poor arc striking with sticking or 1. Make sure the wire feed speed,  
“blast-offs”. The weld bead may be  
ropy and narrow.  
voltage, polarity and shielding  
gas are correct for the process  
being used.  
2. Make sure the welding power  
source is functioning properly.  
3. Make certain the gas solenoid is  
operating properly and the gas  
flow rate is correct for the pro-  
cedure.  
4. The welding gun may be faulty.  
Check for gas leaks or replace  
gun.  
CAUTION  
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your  
Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.  
LN-742 & LN-742H  
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F-1  
F-1  
DIAGRAMS  
LN-742 & LN-742H  
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NOTES  
LN-742 & LN-742H  
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NOTES  
LN-742 & LN-742H  
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F-4  
F-4  
NOTES  
LN-742 & LN-742H  
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F-5  
F-5  
NOTES  
LN-742 & LN-742H  
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● Do not touch electrically live parts or  
electrode with skin or wet clothing.  
● Insulate yourself from work and  
ground.  
● Keep flammable materials away.  
● Wear eye, ear and body protection.  
WARNING  
Spanish  
● No toque las partes o los electrodos ● Mantenga el material combustible  
● Protéjase los ojos, los oídos y el  
bajo carga con la piel o ropa moja-  
da.  
● Aislese del trabajo y de la tierra.  
fuera del área de trabajo.  
cuerpo.  
AVISO DE  
PRECAUCION  
French  
● Ne laissez ni la peau ni des vête-  
ments mouillés entrer en contact  
avec des pièces sous tension.  
● Gardez à l’écart de tout matériel  
inflammable.  
● Protégez vos yeux, vos oreilles et  
votre corps.  
ATTENTION  
● Isolez-vous du travail et de la terre.  
German  
● Berühren Sie keine stromführenden  
Teile oder Elektroden mit Ihrem  
Körper oder feuchter Kleidung!  
● Isolieren Sie sich von den  
● Entfernen Sie brennbarres Material! ● Tragen Sie Augen-, Ohren- und Kör-  
perschutz!  
WARNUNG  
Elektroden und dem Erdboden!  
Portuguese  
● Não toque partes elétricas e elec-  
trodos com a pele ou roupa molha-  
da.  
● Mantenha inflamáveis bem guarda- ● Use proteção para a vista, ouvido e  
dos.  
corpo.  
ATENÇÃO  
● Isole-se da peça e terra.  
Japanese  
Chinese  
Korean  
Arabic  
READ AND UNDERSTAND THE MANUFACTURER’S INSTRUCTION FOR THIS EQUIPMENT AND THE CONSUMABLES TO BE  
USED AND FOLLOW YOUR EMPLOYER’S SAFETY PRACTICES.  
SE RECOMIENDA LEER Y ENTENDER LAS INSTRUCCIONES DEL FABRICANTE PARA EL USO DE ESTE EQUIPO Y LOS  
CONSUMIBLES QUE VA A UTILIZAR, SIGA LAS MEDIDAS DE SEGURIDAD DE SU SUPERVISOR.  
LISEZ ET COMPRENEZ LES INSTRUCTIONS DU FABRICANT EN CE QUI REGARDE CET EQUIPMENT ET LES PRODUITS A  
ETRE EMPLOYES ET SUIVEZ LES PROCEDURES DE SECURITE DE VOTRE EMPLOYEUR.  
LESEN SIE UND BEFOLGEN SIE DIE BETRIEBSANLEITUNG DER ANLAGE UND DEN ELEKTRODENEINSATZ DES HER-  
STELLERS. DIE UNFALLVERHÜTUNGSVORSCHRIFTEN DES ARBEITGEBERS SIND EBENFALLS ZU BEACHTEN.  
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● Keep your head out of fumes.  
● Use ventilation or exhaust to  
remove fumes from breathing zone.  
● Turn power off before servicing.  
● Do not operate with panel open or  
guards off.  
WARNING  
Spanish  
● Los humos fuera de la zona de res-  
piración.  
● Mantenga la cabeza fuera de los  
humos. Utilice ventilación o  
aspiración para gases.  
● Desconectar el cable de ali-  
mentación de poder de la máquina  
antes de iniciar cualquier servicio.  
● No operar con panel abierto o  
guardas quitadas.  
AVISO DE  
PRECAUCION  
French  
● Débranchez le courant avant l’entre- ● N’opérez pas avec les panneaux  
tien.  
● Gardez la tête à l’écart des fumées.  
● Utilisez un ventilateur ou un aspira-  
teur pour ôter les fumées des zones  
de travail.  
ouverts ou avec les dispositifs de  
protection enlevés.  
ATTENTION  
German  
● Strom vor Wartungsarbeiten  
abschalten! (Netzstrom völlig öff-  
nen; Maschine anhalten!)  
● Anlage nie ohne Schutzgehäuse  
oder Innenschutzverkleidung in  
Betrieb setzen!  
● Vermeiden Sie das Einatmen von  
Schweibrauch!  
● Sorgen Sie für gute Be- und  
Entlüftung des Arbeitsplatzes!  
WARNUNG  
Portuguese  
● Não opere com as tampas removidas.  
● Desligue a corrente antes de fazer  
serviço.  
● Mantenha-se afastado das partes  
moventes.  
● Não opere com os paineis abertos  
ou guardas removidas.  
● Mantenha seu rosto da fumaça.  
● Use ventilação e exhaustão para  
remover fumo da zona respiratória.  
ATENÇÃO  
● Não toque as partes elétricas nuas.  
Japanese  
Chinese  
Korean  
Arabic  
LEIA E COMPREENDA AS INSTRUÇÕES DO FABRICANTE PARA ESTE EQUIPAMENTO E AS PARTES DE USO, E SIGA AS  
PRÁTICAS DE SEGURANÇA DO EMPREGADOR.  
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• 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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