Lincoln Electric Welder TIG 375 User Manual

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IM898

March, 2008

PRECISION TIG 375

For use with machines having Code Numbers:

11161, 11162

Safety Depends on You

Lincoln arc welding and cutting

equipment is designed and built

with safety in mind. However, your

overall safety can be increased by

proper installation ... and thoughtful

operation on your part. DO NOT

INSTALL, OPERATE OR REPAIR

THIS EQUIPMENT WITHOUT

READING THIS MANUAL AND

THE SAFETY PRECAUTIONS

CONTAINED

THROUGHOUT.

And, most importantly, think before

you act and be careful.

Precision TIG 375 Welding

Package shown with optional

Advanced Control Panel

IP21S

OPERATORʼS MANUAL

• 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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SAFETY

ARC RAYS can burn.

ELECTRIC SHOCK can kill.

3.a. The electrode and work (or ground) circuits

are electrically “hot” when the welder is on.

Do not touch these “hot” parts with your bare

skin or wet clothing. Wear dry, hole-free

gloves to insulate hands.

4.a. Use a shield with the proper filter and cover

plates to protect your eyes from sparks and

the rays of the arc when welding or observing

open arc welding. Headshield and filter lens

should conform to ANSI Z87. I standards.

4.b. Use suitable clothing made from durable flame-resistant

material to protect your skin and that of your helpers from

the arc rays.

3.b. Insulate yourself from work and ground using dry insulation.

Make certain the insulation is large enough to cover your full

area of physical contact with work and ground.

4.c. Protect other nearby personnel with suitable, non-flammable

screening and/or warn them not to watch the arc nor expose

themselves to the arc rays or to hot spatter or metal.

In addition to the normal safety precautions, if welding

must be performed under electrically hazardous

conditions (in damp locations or while wearing wet

clothing; on metal structures such as floors, gratings or

scaffolds; when in cramped positions such as sitting,

kneeling or lying, if there is a high risk of unavoidable or

accidental contact with the workpiece or ground) use

the following equipment:

FUMES AND GASES

can be dangerous.

5.a. Welding may produce fumes and gases

hazardous to health. Avoid breathing these

• Semiautomatic DC Constant Voltage (Wire) Welder.

• DC Manual (Stick) Welder.

fumes and gases. When welding, keep

• AC Welder with Reduced Voltage Control.

your head out of the fume. Use enough

ventilation and/or exhaust at the arc to keep

3.c. In semiautomatic or automatic wire welding, the electrode,

electrode reel, welding head, nozzle or semiautomatic

welding gun are also electrically “hot”.

fumes and gases away from the breathing zone. When

welding with electrodes which require special

ventilation such as stainless or hard facing (see

instructions on container or MSDS) or on lead or

cadmium plated steel and other metals or coatings

which produce highly toxic fumes, keep exposure as

low as possible and below Threshold Limit Values (TLV)

using local exhaust or mechanical ventilation. In

confined spaces or in some circumstances, outdoors, a

respirator may be required. Additional precautions are

also required when welding on galvanized steel.

3.d. Always be sure the work cable makes a good electrical

connection with the metal being welded. The connection

should be as close as possible to the area being welded.

3.e. Ground the work or metal to be welded to a good electrical

(earth) ground.

3.f. Maintain the electrode holder, work clamp, welding cable and

welding machine in good, safe operating condition. Replace

damaged insulation.

5. b. The operation of welding fume control equipment is affected

by various factors including proper use and positioning of the

equipment, maintenance of the equipment and the specific

welding procedure and application involved. Worker expo-

sure level should be checked upon installation and periodi-

cally thereafter to be certain it is within applicable OSHA PEL

and ACGIH TLV limits.

3.g. Never dip the electrode in water for cooling.

3.h. Never simultaneously touch electrically “hot” parts of

electrode holders connected to two welders because voltage

between the two can be the total of the open circuit voltage

of both welders.

5.c. 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 prod-

ucts.

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.d. 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.

5.e. Read and understand the manufacturerʼs instructions for this

equipment and the consumables to be used, including the

material safety data sheet (MSDS) and follow your

employerʼs safety practices. MSDS forms are available from

your welding distributor or from the manufacturer.

5.f. Also see item 1.b.

AUG 06

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iii

SAFETY

WELDING and CUTTING

CYLINDER may explode

if damaged.

SPARKS can

cause fire or explosion.

6.a. Remove fire hazards from the welding area.

If this is not possible, cover them to prevent

the welding sparks from starting a fire.

7.a. Use only compressed gas cylinders

containing the correct shielding gas for the

process used and properly operating

regulators designed for the gas and

Remember

that

welding

sparks

and

hot

pressure used. All hoses, fittings, etc. should be suitable for

the application and maintained in good condition.

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.

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.

•A safe distance from arc welding or cutting operations and

any other source of heat, sparks, or flame.

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.

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.

8.a. Turn off input power using the disconnect

switch at the fuse box before working on

the equipment.

6.g. Connect the work cable to the work as close to the welding

area as practical. Work cables connected to the building

framework or other locations away from the welding area

increase the possibility of the welding current passing

through lifting chains, crane cables or other alternate circuits.

This can create fire hazards or overheat lifting chains or

cables until they fail.

8.b. Install equipment in accordance with the U.S. National

Electrical Code, all local codes and the manufacturerʼs

recommendations.

8.c. Ground the equipment in accordance with the U.S. National

Electrical Code and the manufacturerʼs recommendations.

6.h. Also see item 1.c.

6.I. Read and follow NFPA 51B “ Standard for Fire Prevention

During Welding, Cutting and Other Hot Work”, available from

NFPA, 1 Batterymarch Park,PO box 9101, Quincy, Ma

022690-9101.

Jan, 07

6.j. Do not use a welding power source for pipe thawing.

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SAFETY

PRÉCAUTIONS DE SÛRETÉ

6. Eloigner les matériaux inflammables ou les recouvrir afin de

prévenir tout risque dʼincendie dû aux étincelles.

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:

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 dʼincendie.

Sûreté Pour Soudage A LʼArc

8. Sʼassurer que la masse est connectée le plus prés possible de

la zone de travail quʼil est pratique de le faire. Si on place la

masse sur la charpente de la construction ou dʼautres endroits

éloignés de la zone de travail, on augmente le risque de voir

passer le courant de soudage par les chaines de levage,

câbles de grue, ou autres circuits. Cela peut provoquer des

risques dʼincendie ou dʼechauffement des chaines et des

câbles jusquʼà ce quʼils se rompent.

1. Protegez-vous contre la secousse électrique:

a. Les circuits à lʼélectrode 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 sʼisoler de la masse quand on

soude dans des endroits humides, ou sur un plancher met-

allique 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 defonc-

tionnement.

d.Ne jamais plonger le porte-électrode dans lʼeau pour le

refroidir.

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 sʼapplicuent aussi au pistolet de

soudage.

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.

10. Ne pas souder en présence de vapeurs de chlore provenant

dʼopérations de dégraissage, nettoyage ou pistolage. La

chaleur ou les rayons de lʼarc peuvent réagir avec les vapeurs

du solvant pour produire du phosgéne (gas fortement toxique)

ou autres produits irritants.

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 nʼimporte quelle partie du

corps.

PRÉCAUTIONS DE SÛRETÉ POUR

LES MACHINES À SOUDER À

TRANSFORMATEUR ET À

REDRESSEUR

3. Un coup dʼarc peut être plus sévère quʼun coup de soliel, donc:

a. Utiliser un bon masque avec un verre filtrant approprié ainsi

quʼun verre blanc afin de se protéger les yeux du rayon-

nement de lʼarc et des projections quand on soude ou

quand on regarde lʼarc.

b. Porter des vêtements convenables afin de protéger la peau

de soudeur et des aides contre le rayonnement de lʻarc.

c. Protéger lʼautre personnel travaillant à proximité au

soudage à lʼaide dʼécrans appropriés et non-inflammables.

1. Relier à la terre le chassis du poste conformement au code de

lʼélectricité et aux recommendations du fabricant. Le dispositif

de montage ou la piece à souder doit être branché à une

bonne mise à la terre.

2. Autant que possible, Iʼinstallation et lʼentretien du poste seront

effectués par un électricien qualifié.

4. Des gouttes de laitier en fusion sont émises de lʼarc de

soudage. Se protéger avec des vêtements de protection libres

de lʼhuile, tels que les gants en cuir, chemise épaisse, pan-

talons sans revers, et chaussures montantes.

3. Avant de faires des travaux à lʼinterieur de poste, la debranch-

er à lʼinterrupteur à la boite de fusibles.

4. Garder tous les couvercles et dispositifs de sûreté à leur place.

5. Toujours porter des lunettes de sécurité dans la zone de

soudage. Utiliser des lunettes avec écrans lateraux dans les

zones où lʼon pique le laitier.

Mar. ʻ93

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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

CUSTOMER ASSISTANCE POLICY

The business of The Lincoln Electric Company is manufacturing and selling high quality welding equipment, consumables, and cutting equip-

ment. Our challenge is to meet the needs of our customers and to exceed their expectations. On occasion, purchasers may ask Lincoln Electric

for advice or information about their use of our products. We respond to our customers based on the best information in our possession at that

time. Lincoln Electric is not in a position to warrant or guarantee such advice, and assumes no liability, with respect to such information or

advice. We expressly disclaim any warranty of any kind, including any warranty of fitness for any customerʼs particular purpose, with respect

to such information or advice. As a matter of practical consideration, we also cannot assume any responsibility for updating or correcting any

such information or advice once it has been given, nor does the provision of information or advice create, expand or alter any warranty with

respect to the sale of our products.

Lincoln Electric is a responsive manufacturer, but the selection and use of specific products sold by Lincoln Electric is solely within the control

of, and remains the sole responsibility of the customer. Many variables beyond the control of Lincoln Electric affect the results obtained in

applying these types of fabrication methods and service requirements.

Subject to Change – This information is accurate to the best of our knowledge at the time of printing. Please refer to www.lincolnelectric.com

for any updated information.

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.

Installation ..........................................................................................................Section A

Technical Specifications ........................................................................................A-1,A-2

Safety Precautions^{.. ............................................................................................................................................... .}A-3

Select Suitable Location........................................................................................A-3

Grinding .................................................................................................................A-3

Stacking.................................................................................................................A-3

Undercarriage Lifting and Moving .........................................................................A-3

Tilting .....................................................................................................................A-3

Environmental Rating ............................................................................................A-3

Machine Grounding and High Frequency Interference Protection .......................A-3, A-4

Input and Grounding Connections..............................................................................A-4

Output Cable, Connections and Limitations ................................................................A-5

Work Cable Connection..................................................................................A-5

Stick Electrode Cable Connection ..................................................................A-5

TIG Torch Connection.....................................................................................A-6

Auxiliary Power Connections ..........................................................................A-7

Remote Control (If Used)................................................................................A-7

Robotic Interface Connection ..................................................................A-7, A-8

________________________________________________________________________

OPERATION..........................................................................................................................................................Section B-1

Safety Precautions.......................................................................................................B-1

Product Description......................................................................................................B-1

Pipe Thawing.........................................................................................................B-1

Duty Cycle: ............................................................................................................B-1

Recommended Processes and Equipment...........................................................B-2

Controls and Settings .............................................................................B-3 Thru B-6

Internal Set Up Controls........................................................................................B-7

Stick Welding Features..........................................................................................B-7

TIG Welding Features ...........................................................................................B-7

2 Step Trigger Modes......................................................................................B-8

4 Step Trigger Modes ....................................................................................B-9

TIG Welding Cycle Chart ....................................................................................B-10

Setup Guidelines for TIG Welding with an Amptrol.....................................B-10, B11

Making a TIG Weld with an Amptrol....................................................................B-12

________________________________________________________________________

Accessories ^{............................................................................................................................................... .......}Section C

Optional Equipment .....................................................................................................C-1

________________________________________________________________________

Maintenance^{......................................................................................................................................................}Section D

Safety Precautions.......................................................................................................D-1

Routine and Periodic Maintenance..............................................................................D-1

Overload Protection.....................................................................................................D-1

Service Procedures, Component Access,Spark Gap Adjustment...............................D-2

Under-Cooler Service ..................................................................................................D-2

________________________________________________________________________

Troubleshooting^{.............................................................................................................................................}Section E

Safety Precautions.......................................................................................................E-1

How To Use TroubleShooting Guide............................................................................E-1

Troubleshooting .................................................................................................E-2 to E-7

________________________________________________________________________

Diagrams^{..............................................................................................................................................................}Section F

Wiring Diagrams..............................................................................................................................................F-1, F-2

Dimension Prints .............................................................................................................................................F-3, F-4

________________________________________________________________________

Parts List^{......................................................................................................................................................................}P-558

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A-1

INSTALLATION

TECHNICAL SPECIFICATIONS-PRECISION TIG 375 (K2624-1 Domestic Package*-60Hz)

(K2622-1 Domestic,K2622-2 Canadian-60Hz)

RATED INPUT - SINGLE PHASE ONLY

Duty Cycle-Applications

Voltage + 10%

Max. Amps With Power Factor Capacitor

Number

40%

AC/DC Stick / Balance TIG

112/102/51

139/126/63

Unbalance (70% Penetration ) AC TIG

60%

K2622-1

K2624-1

AC/DC Stick / Balance TIG

102/92/46

Unbalance (70% Penetration ) AC TIG

208/230/460

128/116/58

100%

AC/DC Stick / Balance TIG

80/72/36

104/92/47

68/62/31

Unbalance (70% Penetration ) AC TIG

Idle Amps

40%

AC/DC Stick / Balance TIG

102/51/41

125/63/50

Unbalance (70% Penetration ) AC TIG

60%

AC/DC Stick / Balance TIG

92/46/37

Unbalance (70% Penetration ) AC TIG

116/58/46

100%

230/460/575

K2622-2

AC/DC Stick / Balance TIG

72/36/29

94/47/38

Unbalance (70% Penetration ) AC TIG

Idle Amps

Rated Power Factor (Stick)

Idle Power

62/31/25

.86 min.

1.0KW

RATED OUTPUT - NEMA EW1 Class ll (40)

Duty Cycle-Applications

Volts at Rated Amperes

Amps

40%

AC/DC Stick / Balance TIG

35.0

17.2

375

350

Unbalance (70% Penetration ) AC TIG

60%

AC/DC Stick / Balance TIG

34.0

16.9

350

325

Unbalance (70% Penetration ) AC TIG

100%

AC/DC Stick / Balance TIG

32.0

16.3

300

275

Unbalance (70% Penetration ) AC TIG

*Shown on Front of this IM manual with Under-Cooler Cart and Advanced Control Panel (Refer to Optional Equipment)

^#Exceeds NEMA Unbalanced Load Specification comparable for Auto-Balance.

PRECISION TIG 375

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A-2

INSTALLATION

ADDITIONAL OUTPUT CAPACITY

Output Current

Maximum Open

Type of Output

Auxiliary Power

Range

Circuit Voltage

15Amp Circuit Breaker and NEMA 5-15R Duplex

Receptacle for up to:

2Amps DC

(STICK AND TIG)

AC/DC OCV: 80

CC (Constant Current)

AC/DC (GTAW)

115VAC 8 Amp Auxiliary Power Receptacle

115VAC 5 Amp weld Switched Cooler Receptacle

420Amps AC-DC*

Stick (SMAW)

RECOMMENDED INPUT WIRE AND FUSE SIZES

For all Stick, DC TIG, and Balanced AC TIG Welding

For Unbalanced AC TIG Welding Above 275 Amps:

350A/40% Duty Cycle, Auto-Balance Penetration with

out Standard Power Factor Correction Capacitors

Based on the 1999 U.S. National Electrical Code

at 375A/40% Duty Cycle with out Standard Power

Factor Correction Capacitors

Based on the 1999 U.S. National Electrical Code

Input

Type 75°C

Copper

Type 75°C

Copper Wire in

Conduit AWG

(IEC) Sizes

Type 75°C

Copper Wire in

Conduit AWG

(IEC) Sizes

Type 75°C

Input

Voltage /

phase/

Ampere

Fuse

Input

Fuse

Copper

(Super Lag) Rating

or Breaker Rating on

Ground Wire in (Super Lag) Ampere

Ground Wire in

Conduit AWG

(IEC) Sizes

Rating

Conduit AWG or Breaker

40°C (104°F)

Ambient

40°C (104°F)

Ambient

Size¹

150

Nameplate

(IEC) Sizes

Size¹

200

175

Frequency

208/1/60

230/1/60

460/1/60

112

102

119

6 (13.3 mm )

139

126

118

3 (26.7 mm )

1 (42.4 mm )

6 (13.3 mm )

2 (33.6 mm )

3 (26.7 mm )

6 (13.3 mm )

8 (8.4 mm )

6 (13.3 mm )

6 (13.3mm )

8 (8.4 mm )

575/1/60

10 (5.3mm )

6 (13.3 mm )

8 (8.4 mm )

220-230/1/50/60

380-400/1/50/60

415/1/50/60

150

110

6 (13.3 mm )

150

110

3 (26.7 mm )

6 (13.3 mm )

4 (21.2 mm )

6 (13.3 mm )

4 (21.2 mm )

6 (13.3 mm )

PHYSICAL DIMENSIONS

Height

Width

Depth

Weight

31.0 in.

22.0 in.

26.0 in.

507 lbs.

230 kgs.

K2622-1, -2

K2624-1

787 mm

559 mm

660 mm

49.7 in.

28.0 in.

711 mm

41.0 in.

751 lbs.

341 kgs.

1262 mm

1041 mm

TEMPERATURE RANGES

OPERATING TEMPERATURE RANGE

STORAGE TEMPERATURE RANGE

-20°C to +40°C (-04° to +104°F)

-40°C to +85°C (-40° to +185°F)

TRANSFORMER INSULATION CLASS 180°C (H)

1 _{ALSO CALLED ʻINVERSE TIME" OR "THERMAL/MAGNETIC " CIRCUIT BREAKERS; CIRCUIT BREAKERS WHICH HAVE A DELAY IN TRIPPING ACTION THAT DECREASES AS}

THE MAGNITUDE OF CURRENT INCREASES.

50/60HZ IEC Max. range exceeds 310A.

PRECISION TIG 375

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A-3

INSTALLATION

ENVIRONMENTAL RATING

SAFETY PRECAUTIONS

Read entire installation section before starting

installation.

Precision TIG 375 power sources carry an IP21S

Environmental rating. They are rated for use in damp,

dirty rain-sheltered environments.

WARNING

ELECTRIC SHOCK can kill.

• Only qualified personnel should

perform this installation.

MACHINE GROUNDING AND HIGH FRE-

QUENCY INTERFERENCE PROTECTION

• Turn the input power OFF at the

disconnect switch or fuse box

before working on this

equipment.

The frame of the welder must be grounded. A ground screw

marked with the symbol is located on the input connection

panel (Figure A.1) for this purpose. See your local and nation-

al electrical codes for proper grounding methods.

• Do not touch electrically hot

parts.

The spark gap oscillator in the high frequency genera-

tor, being similar to a radio transmitter, can be blamed

for many radio, TV and electronic equipment interfer-

ence problems. These problems may be the result of

radiated interference. Proper grounding methods can

reduce or eliminate radiated interference.

• Always connect the Precision TIG 375 grounding screw (behind

the reconnect panel cover located near the back of the left case

side) to a good electrical earth ground.

• Always connect the Precision TIG 375 to a power supply

grounded in accordance with the National Electrical Code and

all local codes.

SELECT SUITABLE LOCATION

The Precision TIG 375 has been field tested under rec-

ommended installation conditions and has been found

to comply with F.C.C. allowable radiation limits. This

welder has also been found to comply with NEMA stan-

dards for high frequency stabilized power sources.

Place the welder where clean cooling air can freely cir-

culate in through the top rear vents and out through the

bottom rear vents. Dirt, dust or any foreign material

that can be drawn into the welder should be kept at a

minimum. Failure to observe these precautions can

result in excessive operating temperatures and nui-

sance trips.

Radiated interference can develop in the following four

ways:

• Direct interference radiated from the welder.

• Direct interference radiated from the welding leads.

• Direct interference radiated from feedback into the

power lines.

GRINDING

Do not direct grinding particles towards the welder. An

abundance of conductive material can cause mainte-

nance problems.

• Interference from re-radiation of "pickup" by

ungrounded metallic objects.

STACKING

The Precision TIG 375's cannot be stacked .

Keeping these contributing factors in mind, installing

the equipment per the following instructions should

minimize problems:

UNDERCARRIAGE LIFTING AND MOVING

1. Keep the welder power supply lines as short as pos-

sible. Input leads within 50 feet (15.2 m) of the

welder should be enclosed in rigid metallic conduit

or equivalent shielding. There must be good electri-

cal contact between this conduit and the welder.

Both ends of the conduit must be connected to a

driven ground and the entire length must be contin-

uous.

When the Precision TIG 375 is purchased as a weld-

ing package, or used with any of the available

Undercarriage optional accessories, proper installation

makes the Precision TIG 375 lift bale nonfunctional.

Do not attempt to lift the power source with an under-

carriage attached. The undercarriage is designed for

hand moving only; mechanized movement can lead to

personal injury and/or damage to the Precision TIG

375.

2. Keep the work and electrode leads as short as pos-

sible and as close together as possible. Lengths

should not exceed 25 feet (7.6 m). Tape the leads

together when practical.

TILTING

Each machine must be placed on a secure, level sur-

face, either directly or on a recommended undercar-

riage. The machine may topple over if this precaution

is not followed.

PRECISION TIG 375

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A-4

INPUT and GROUNDING CONNECTIONS

INSTALLATION

3. Be sure the torch and work cable rubber coverings

are free of cuts and cracks that allow high frequen-

cy leakage. Cables with high natural rubber content,

such as Lincoln Stable-Arc®, better resist high fre-

quency leakage than neoprene and other synthetic

rubber insulated cables.

WARNING

ELECTRIC SHOCK can kill.

• Turn the input power OFF at the

disconnect switch or fuse box

before working on this

equipment.

4. Keep the torch in good repair and all connections

tight to reduce high frequency leakage.

Be sure the voltage, phase, and frequency of the input

power is as specified on the rating plate, located on the

rear of the machine.

5. The work terminal must be connected to a ground

within ten feet of the welder, using one of the fol-

lowing methods:

Remove the reconnect panel cover located near the

back of the left case side to reveal the reconnect panel.

Welder supply line entry provision is in the case rear

panel. Entry is through a 1.75 inch (44 mm) diameter

hole in the case back. Appropriate supply line strain

relief clamp is provided by installer. (See Figure A.1)

• A metal underground water pipe in direct contact

with the earth for ten feet or more.

• A 3/4" (19 mm) galvanized pipe or a 5/8" (16 mm)

solid galvanized iron, steel or copper rod driven at

least eight feet into the ground.

FIGURE A.1

The ground should be securely made and the ground-

ing cable should be as short as possible using cable of

the same size as the work cable, or larger. Grounding

to the building frame electrical conduit or a long pipe

system can result in re-radiation, effectively making

these members radiating antennas. (This is not rec-

ommended).

CONNECT INPUT

POWER LEADS

CONNECT INPUT

VOLTAGE LEVEL

GROUND LEAD

6. Keep all access panels and covers securely in

place.

All connections should be made in accordance

with all local codes and national electrical codes.

Installation by a qualified electrician is recom-

mended.

7. All electrical conductors within 50 feet (15.2 m) of

the welder should be enclosed in grounded rigid

metallic conduit or equivalent shielding. Flexible

helically-wrapped metallic conduit is generally not

suitable.

1. Connect the terminal marked

nect panel) to an earth ground.

(below the recon-

2. Connect the input leads to terminals marked L1 (U)

and L2 (V) on the reconnect panel. Use a single

phase line or one phase of a two or three phase line.

8. When the welder is enclosed in a metal building,

several good earth driven electrical grounds (as in 5

above) around the periphery of the building are rec-

ommended.

3. On multiple input voltage welders, be sure the

reconnect panel is connected for the voltage being

supplied to the welder.

Failure to observe these recommended installation

procedures can cause radio or TV interference prob-

lems and result in unsatisfactory welding performance

resulting from lost high frequency power.

CAUTION

Failure to follow these instructions can cause

immediate failure of components within the welder.

------------------------------------------------------------------------

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A-5

INSTALLATION

Welders are shipped connected for the highest input

voltage as listed on the rating plate. To change this

connection, designations on the reconnect panel LOW,

MID, and HIGH correspond to the name plated input

voltages of a triple voltage welder. Dual voltage

welders use only LOW and HIGH.

Recommended Cable Sizes for Combined Lengths of

Copper Work and Electrode Cables using 75 C Wire:

Machine Rating

0 to 100 Ft.

101 to 200 Ft

201 to 250 Ft

375A/40%

#1 (42.4 mm ) 1/0 (53.5 mm ) 2/0 (67.4 mm )

WORK CABLE CONNECTION

EXAMPLE: On a 208/230/460 volt welder, LOW is

208V, MID is 230V, and HIGH is 460V.

A 15ʼ (2/0) weld cable with clamp is available (K2150-1), or

included with the Precision TIG Welding Package model.

Otherwise, it is user provided.

Note: Export model has a voltage range for LOW and

MID connections: LOW is 220-230V, MID is

380-400V and High is 415V.

With power source off, connect a separate work cable

to the 1/2-13 threaded "WORK" stud of the welder, and

secure a tight connection with the flange nut provided.

The work cable should be routed through the cable

strain relief hole provided in the base directly below the

welding output terminal.

Reconnect the jumper strap to the terminal stud corre-

sponding to the input voltage level used. Make sure all

connections are tight.

Fuse the input circuit with the recommended super lag

fuses or delay type1 circuit breakers. Choose an input

and grounding wire size according to local or national

codes or use Section A-2. Using fuses or circuit break-

ers smaller than recommended may result in "nui-

sance" tripping from welder inrush currents even if not

welding at high currents.

Note: If the Precision TIG is equipped with an Under-

Cooler or Under-Storage unit, the coiled work cable

and clamp, or excess work cable length, may be con-

veniently stored in the drawer while remaining con-

nected.

STICK ELECTRODE CABLE CONNECTION

Unbalanced AC TIG welding draws higher input cur-

rents than those for Stick, DC TIG, or Balanced AC TIG

welding. The welder is designed for these higher input

currents. However, where unbalanced AC TIG welding

above 275 amps is planned, the higher input currents

require larger input wire sizes and fuses per Section A-

If manual stick welding is desired, with power source

off, connect a stick electrode cable to the 1/2-13

threaded "STICK Electrode" stud of the welder, and

secure a tight connection with the flange nut provided.

The electrode cable should be routed through the

cable strain relief hole provided in the base directly

below the welding output terminal.

OUTPUT CABLES, CONNECTIONS AND

LIMITATIONS

WARNING

DISCONNECT STICK ELECTRODE WELDING

CABLE WHEN TIG WELDING.

• To avoid being startled by a high frequency

shock, keep the TIG torch and cables in good

condition

EVEN THOUGH HI-FREQ IS NOT APPLIED TO THE

PRECISION TIG STICK TERMINAL, IT WILL BE

ELECTRICALLY "HOT" TO WORK WHEN TIG

WELDING.

• Turn the power switch of the power source OFF

before installing adapters on cable or when con-

necting or disconnecting adapter plugs to power

source.

------------------------------------------------------------------------

-----------------------------------------------------------------------

Refer to Figure A.2 for the location of the WORK and

STICK terminals, as well as the TIG Torch connection

panel.

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A-6

INSTALLATION

FIGURE A.2

TIG TORCH

CONNECTION

PANEL

REMOTE

CONTROL

RECEPTACLE

STICK

WORK

STICK

ELECTRODE

STUD

(Shown without hinged stud cover)

FIGURE A

CABLE

STRAIN

RELIEF HOLES

CYLINDER could explode

if damaged.

TIG TORCH CONNECTION

• Keep cylinder upright and

chained to a support.

The Precision TIG torch connection box, located on the

right side of the machine, provides all the input and

output connections for the installation of both air-

cooled and water-cooled TIG torches with fittings con-

forming to Compressed Gas Association (CGA) stan-

dards:

• Keep cylinder away from areas

where it could be damaged.

• Never allow the torch to touch the cylinder.

• Keep cylinder away from live electrical cir-

cuits.

Note: The Precision TIG provides an insulated Torch

Reel and Holster for handy and safe storage of con-

nected torch when not welding, and excess torch cable

length while welding.

• Maximum inlet pressure 150 psi.

-----------------------------------------------------------------

The Precision TIG machines do not have Hi-Freq.

available at the Stick electrode stud, therefore stud

connection adapters (such as LECO. S19257-series)

cannot be used for torch connection.

WARNING

Combination connectors (Power/Water and

Power/Gas) are electrically "hot" while welding in

STICK or TIG modes.

Single-piece cable air-cooled torches with a 3/8-24 RH

connector fitting (such as the Magnum PTA-9/-17, or LA-

9/-17) require the provided S20403-4 Torch Connector,

while those with a 7/8-14 RH connector fitting (such as

the Magnum PTA-26, or LA-26) require the available

K2166-1 Torch Connector. (See Figure A.3)

If using an Air-Cooled Torch be sure coolant is

shut off and/or Cooler is unplugged from the

Precision TIG Water Cooler Receptacle on the

torch side of the upper case back.

Two-piece cable air-cooled torches (such as PTA-, or LA-

torches) can be used with the available K2166-2 1/2”

Stud Connector with with a 7/8-14 LH male fitting.

Observe the safety precautions necessary for han-

dling and using compressed gas containers.

Contact your supplier for specifics.

Magnum PTW-18/-20 (or LW-) water-cooled Torches

require no adapter for Precision TIG connection.

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A-7

INSTALLATION

FIGURE A.3

For Gas Supply hose

with 5/8-18RH male

(Provided with Weld

Package model)

1/2-13

Stud

For Coolant Supply

Hoses

with 5/8-18LH male

(Provided with Weld

Package model

Under-Cooler Cart)

The Precision TIG Export models also provide a

grounded 220vac Euro type Schuko receptacle and a

5 amp circuit breaker, located on the upper case back

on the reconnect side of the machine, intended for use

with a 220vac water cooler.

AUXILIARY POWER CONNECTIONS

The Precision TIG machines provide a standard NEMA

5-15R duplex receptacle, located on the upper case

back on the torch side of the machine:

• The bottom outlet of this duplex receptacle provides

switched 115VAC power for the Under-Cooler, or

Water Solenoid accessory. This Cooler receptacle

turns on when the arc starts and remains on for about

8 minutes after the arc goes out (with the Fan-As-

Needed machine cooling fan, see Maintenance

Section), so the Coolerʼs fan and water pump will not

run continuously in idle, but will run while welding.

REMOTE CONTROL (If Used)

The Foot Amptrol (included with the Precision TIG

Welding Package), or other Remote accessory, is

installed by routing the plug of its control cable up

through the left cable strain relief hole provided in the

base (see Figure A.2), then connecting the 6-pin plug

to the mating Remote receptacle behind the stud panel

cover. (See Operation Section B-2 for mating plug

wiring.)

• The top outlet of this duplex receptacle provides at

least 8 amps at 115VAC, whenever the Precision TIG

Power switch is ON. This auxiliary circuit is intended

for running 115VAC accessories or small power tools.

Note: Some types of equipment, especially pumps

and large motors, have starting currents which are

significantly higher than their running current. These

higher starting currents may cause the circuit breaker

to open. (See next paragraph)

Note: If the Precision TIG is equipped with an Under-

Cooler or Under-Storage unit, the Foot Pedal (or other

remote control accessory) and coiled control cable, or

excess cable length, may be conveniently stored in the

drawer while remaining connected.

• Both the receptacle circuits are protected from shorts

and overloads by a 15 amp circuit breaker, located

above the receptacle. If the breaker trips, its button

pops out exposing a red ring. When the circuit break-

er cools, the button can be reset by pressing it back

in.

Note: When the breaker trips, not only will the auxil-

iary and cooler power be interrupted, but so will the

power to the shielding gas solenoid and machine

cooling fan.

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A-8

INSTALLATION

ROBOTIC INTERFACE CONNECTION

Robotic interface can be made at the Remote

Receptacle (See Operation Section B-2). The machine

is shipped with the remote receptacle circuit internally

connected to receptacle J5 of the Control board for

standard Amptrol operation. In order to enable the

remote receptacle for robotic interface its connection

plug must be moved from J5 to J5A on the Control

board. (Refer to the machine Wiring Diagram.)

The robotic interface functions with the Precision TIG

set to either TIG or STICK mode, but must be in

REMOTE switch position for the Preset Control inter-

face to function. When in the REMOTE position with

robotic interface neither the MAXIMUM OUTPUT nor

the MINIMUM OUTPUT panel controls limit the inter-

face control setting over the rated output range of the

machine.

The diagram in Figure A.4 below shows the remote

receptacle plug connections and signals for robotic

interface:

FIGURE A.4

In addition; a Peak Pulse output signal is provided at

J21 receptacle on the Advanced Control PCB. This

output provides a 0.2A rated switch circuit between pin

1 (+) and pin 2 (com) for an external 40VDC supplied

relay (with coil diode). This switch closes when the

Peak Pulse is on, and opens when off.

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B-1

OPERATION

SAFETY PRECAUTIONS

PRODUCT DESCRIPTION

Read and understand this entire section before operat-

The Precision TIG 375 is part of a new family of indus-

trial arc welding power sources providing constant cur-

rent, single range square wave AC/DC TIG (GTAW)

ing the machine.

with patented Micro-Start II Technology, Presettable

WARNING

Min. and Max. Output controls, and built-in high fre-

quency stabilization for continuous AC TIG and DC TIG

starting. It also has AC/DC Stick (SMAW) capability,

with adjustable Arc Force availability. A TIG Pulse

Panel, Power Factor Capacitors and a Water Solenoid

are available as field installed optional kits. Also, a new

Undercarriage (with double gas bottle rack) is available

for field installation, as well as a new Under-Cooler

Cart, which is also included in an available efficiently

integrated entire TIG Welding Package with conve-

nient built-in storage provisions for welding equipment

and components.

ELECTRIC SHOCK can kill.

• Only qualified personnel should

perform this installation.

• Turn the input power OFF at the

disconnect switch or fuse box.

• Do not touch electrically live parts

or electrode with skin or wet cloth-

ing.

•

Insulate yourself from work and

ground.

• Always wear dry insulating gloves.

•

Read and follow “Electric Shock

Warnings” in the Safety section if weld-

ing must be performed under electrical-

ly hazardous conditions such as weld-

ing in wet areas or on or in the work-

piece.

The Precision TIG 375 includes advanced features

such as: Digital Meter, Presettable control, Auto

Balance™, Fan As Needed (F.A.N.) and Timers for

fixed Peflow and variable Postflow shielding gas. Also

2-Step/4-Step and Pulse TIG operation with adjustable

Downslope Time control advanced controls are includ-

ed. The model still features a Stick stud panel and a

universal TIG torch connection box for simultaneous,

but separated, electrode outputs.

FUMES AND GASES

can be dangerous.

• Keep your head out of fumes.

• Use ventilation or exhaust to

remove fumes from breathing

zone.

The Precision TIG 375 has enhanced Features which

includes the following:

WELDING SPARKS

• MicroStart™ II

can cause fire or

• Auto-Balance optimized

• Menu button added

• Spot On selection added

explosion

• Keep flammable material away.

• Do not weld on containers that

have held combustibles.

PIPE THAWING

ARC RAYS

can burn.

The Precision TIG 375 is not recommended for pipe

thawing.

• Wear eye, ear and body

protection.

Duty Cycle

The duty cycle is based upon a 10-minute time period;

i.e., for 40% duty cycle, it is 4 minutes welding and 6

minutes idling. If the rated duty cycle is significantly

exceeded, the thermostatic protection will shut off the

output until the machine cools to a normal operating

temperature. (Refer to Specification Section A-1)

Observe additional Safety Guidelines detailed in

the beginning of this manual.

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B-2

OPERATION

EQUIPMENT LIMITATIONS

RECOMMENDED PROCESSES AND

EQUIPMENT

The Precision TIG machines are protected from over-

loads beyond the electrical ratings and duty cycles, per

the Specifications Section A-1, A-2, with Thermostat

protection of the primary and secondary transformer

coils.

RECOMMENDED PROCESSES

The Precision TIG 375 is recommended for the TIG

(GTAW) and Stick (SMAW) welding processes within

its output capacity range of 2 amps DC, or 5 amps AC,

to 420 amps AC/DC. It is compatible with most

Magnum TIG accessories (refer Equipment

Limitations), as well as many industry standard items,

such as TIG torches, hoses, and water coolers.

The Precision TIG machines do not have Hi-Frequency

available at the Stick electrode stud, therefore stud

connection adapters (such as LECO. S19257-series)

cannot be used for torch connection.

PROCESS LIMITATIONS

Precision TIG machines are not recommended for arc

gouging due to it's limited output capacity, and are also

not recommended for pipe thawing.

RECOMMENDED EQUIPMENT/INTERFACE

TIG (water cooled)

TIG (air cooled)

PT375(K2622-1, -2)

User provided

Machine:

PT375 Welding Package (K2624-1)

User provided

Input Cable/Clamp:

Gas Reg./Hose:

Magnum Torch:

Magnum Parts:

Work Clamp/Lead:

Foot Amptrol:

(included)

LE/Harris 3100211

PTA9 or PTA17

KP507 or KP508

K2150-1 Work Lead Assembly

K870

(PTW20 included)

(KP510 and K918-2 included)

(15 ft. included)

(K870 included)

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B-3

OPERATION

CONTROLS AND SETTINGS

The Front Control Panel contains the knobs and switches necessary for adjusting the operation of the Precision

TIG 375, with function indicator lights and an electronic display for volts and amps. The components are

described below:

FIGURE B.1 - CONTROL PANEL

1. POWER SWITCH

2. POLARITY SWITCH

3. MODE SWITCH

4. AC BALANCE CONTROL

5. LOCAL/REMOTE CURRENT CONTROL

SWITCH

6. MAXIMUM OUTPUT CONTROL

7. MINIMUM OUTPUT CONTROL AND

DISPLAY SWITCH

7a . MENU BUTTON AND DISPLAY

SWITCH

8. DIGITAL METER AND DISPLAY

SWITCH

9. POSTFLOW TIME

10. THERMAL SHUTDOWN LIGHT

11. REMOTE RECEPTACLE

12. TRIGGER SWITCH

13. PULSE / SPOT MODE SWITCH

14. PULSE FREQUENCY CONTROL

15. PULSE % ON TIME CONTROL

16. PULSE BACKGROUND CURRENT

CONTROL

13 14

15 16 17

17. DOWNSLOPE TIME

18. INTERNAL SETUP SELECTIONS

(NOT SHOWN)INSIDE PANEL.

19. HIGH FREQUENCY INTENSITY

CONTROL (NOT SHOWN, LOCATION

ONLY)ON SIDE OF MACHINE.

1. POWER SWITCH - Input line switch turns input

power ON or OFF, as indicated by the on or off sta-

tus of the front panel displays.

• The CC Stick mode may be used for general pur-

pose stick welding (SMAW ) within the capacity of

the machine. The capacity is too limited for arc air

carbon (AAC) gouging.

2. POLARITY SWITCH – The 3-position rotary power

switch has detente positions for DC-, AC and DC+

selections for the Electrode output welding polarity.

• In this mode; the output terminals are activated

electrically HOT, gas flow is not activated and HOT

START and ARC FORCE levels are fixed, or

Advanced Panel selectable (See Section B-7 ), with

no front panel adjustment.

3. MODE SWITCH – The mode switch allows vertical-

ly positioned selection of the two machine welding

modes. The selected mode is indicated by a lit col-

ored panel light which permits viewing the machine

setting from a distance:

3.b TIG mode (Bottom position) – No panel light.

• When the Polarity Switch is set to AC, the TIG

mode provides continuous high frequency to stabi-

lize the arc for AC TIG welding.

3.a STICK mode (Top position) –Red panel light

WARNING

Hi-Freq. turns on after preflow time with the arc

start switch closure, and turns off when the arc

goes out* after the arc start switch opens.

ELECTRIC SHOCK can kill.

• When the Power Source is ON in

STICK mode the Electrode circuits of

both the Stick and TIG torch cables

* Arc voltage and current are sensed to determine if

are electrically HOT to Work.

the arc is established or out.

------------------------------------------------------------------------

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B-4

OPERATION

• When the Polarity Switch is set to DC (- or +), the

TIG mode provides high frequency only for starting.

• With the Current Control switch to REMOTE posi-

tion, this knob sets the maximum welding level that

the Peak output can be set with the remote Amptrol.

Hi-Freq. turns on after pre-flow time with the arc

start switch closure, and turns off when the arc is

established.*

• The new MicroStart Technology minimum current

circuit provides for low end welding (down to 2

amps) previously unobtainable on an SCR platform

TIG machine.

• Also functions for DC+ polarity to permit "balling" of

tungsten for AC TIG welding.

7. MINIMUM OUTPUT CONTROL AND DISPLAY SWITCH

–

4. AC BALANCE CONTROL – The potentiometer

control permits AC wave balance adjustment from

Max. Penetration (~85% negative wave) with the

control at Max. full CW position, to Max. Cleaning

(~65% positive wave) with the control set near min-

imum CCW position.

A smaller knob is used to preset the minimum cur-

rent level only for TIG mode. Pressing the Display

(momentary) switch toggle left to Minimum Set posi-

tion displays the Minimum control level setting on the

Digital meter. (See Item 8)

• This knob sets the Start output level. When the arc

lights (using a new built-in TIG start pulse) this level

upslopes quickly (0.5 sec.w/ Advanced Panel, zero

w/o-See UP Menu of Item 7a) and smoothly to the

weld output level. The setting range for this Start

control is the 2 amp minimum range of the machine

up to about 50 amps, but no more than the level set

by the Maximum Output control knob (See Item 6),

but otherwise is independent of the Maximum set-

ting.

• Full minimum CCW position is the Auto Balance

position which is indicated by the Green panel light

turning on. This feature automatically provides the

proper amount of cleaning and penetration for nor-

mal AC TIG welding

• The mid position is the Balanced position (~50%

positive and negative waves).

• The Balance control is only functional if the machine

is set to AC polarity and TIG mode.

• This setting also serves as the Crater-fill level, but

with a Precision TIG Advanced Panel it can be

selected (see Section B-7) to be either the Minimum

Output control setting (same as Start setting) as

shipped, or the minimum rating of the machine (2

amps).

5. LOCAL/REMOTE CURRENT CONTROL SWITCH – A

2-position switch selects how the welding output is

controlled for both Stick and TIG Modes:

• LOCAL (Top position) selects output control only by

the machine panel Output Control. (See Item 6)

• The Remote Amptrol range of control is between

this Minimum setting and the Maximum Output con-

trol knob setting, so these knobs can set the resolu-

tion of the Amptrol. Also, the Minimum setting

serves as both the minimum Amptrol start level

when the arc start switch is closed, as well as the

minimum Amptrol crater-fill level before the arc start

switch is opened to help prevent premature arc out

and Hi-Freq re-initiation.

• REMOTE (Bottom position) selects output control to

also be by an Amptrol (See Item 6), or other remote

(10K pot) control connected to the Remote recepta-

cle (See Item 11). This switch selection is indicted

by the Green panel light turning on.

In either position the arc start switch functions when

connected to the Remote receptacle (See Item 11).

• In STICK mode the Start control is not functional

since Hot Start level is fixed, or internal Advanced

Panel adjustable (see Section B-7). Pressing the

Display (momentary) switch toggle left to Minimum

Output position displays minimum amps rating of

the machine.

6. MAXIMUM OUTPUT CONTROL – The large knob

is used to set the output welding current over the

rated output range of the machine.

• With the Current Control switch to LOCAL position,

this knob sets the welding output level.

* Arc voltage and current are sensed to determine if

the arc is established or out.

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B-5

OPERATION

7a MENU BUTTON AND DISPLAY SWITCH –

Pressing and holding the (Menu) Button for about 5

seconds enters the menu display which allows:

TIG Mode Menu (with Advanced Control Panel installed):

Setting: Description:

Selection 4: HS (TIG Hot Start % of output setting)

0 *

+0%

(Only setting for SS0, above.)

• Selection of up to seven programmable parameters

(Preflow, Upslope, Hot Start, Arc Force, etc.) is dis-

played on the digital meter by momentarily pressing

and releasing the MENU button to step through the

parameters.

+10%

+20%

+30%

+40%

+50%

+60%

+70%

+80%

+90%

• Setting of the desired level, displayed on the digital

meter for the selected parameter, by pressing the

DISPLAY (momentary) switch toggle to the right to

increase the level setting, or to the left to decrease it.

Selection 5: UP (Upslope Time)

None

(Only setting for SS1 & SS2, above.)

0.5 sec.

1.0 sec.

1.5 sec.

2.0 sec.

2.5 sec.

DIGITAAL DISPLAY

* Default Factory Setting. (Indicated by "blinking" decimal point.)

(SET)

(SELECT)

DISPLAY

◊

STICK Mode Menu (with Advanced Control Panel installed ):

Setting: Description:

Selection 6: HS (Stick Hot Start % added to output setting)

+0%

+10%

+20%

+30%

+40%

+50%

+60%

+70%

+80%

+90%

TIG Mode Menu

Setting:

Description:

Selection 1: HF (High Freq.)

5 *

1 *

Scratch start TIG (No Hi-Freq.)

Normal Hi-Freq. start and weld

Lift TIG (Touch start w/o Hi-Freq.)

Selection 2: PF (Preflow time)

No Preflow

0.1 sec.

0.5 sec.

1.0 sec.

1.5 sec.

2.0 sec.

Selection 7: AF (Stick Arc Force % added to output setting)

1 *

+0%

("Softer" arc)

2 *

+10%

+20%

+30%

+40%

+50%

+60%

+70%

+80%

+90%

Selection 3: SS (MicroStart™ Start Pulse)

0 *

No AC pulse/Low DC pulse (soft start)

High AC/DC pulse (forceful start)

HS setting (see below) for each pulse when Pulse

mode welding anodized aluminum.

("Crisper" arc)

* Default Factory Setting. (Indicated by "blinking" decimal point.)

Without Factory installed Advanced Control Panel the Stick

^ΔOnly selectable with Factory installed Advanced Control Panel.

◊

menu displays “- - -“.

• Any of the following actions will exit the menu display:

1. Pressing and holding the (Menu) Button again for about 5 seconds.

2. Allowing the menu display to be unchanged for about 15 seconds.

3. Closing the arc start switch (TIG Mode) or starting the arc (Stick Mode).

Note: In Stick Mode the machine output will remain on while in menu display.

• Re-entering the menu displays the last parameter and setting that was displayed when the menu was

exited.

• All settings may be reset to the Factory Default Settings (above) by holding the (Menu) button pressed while

turning on the machineʼs Power switch. The display will show “rES” to indicate the defaults are reset.

PRECISION TIG 375

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B-6

OPERATION

8. DIGITAL METER AND DISPLAY SWITCH– A (3-

digit) LED meter is used to monitor the preset and

actual welding procedure based on the Display

(momentary) switch position:

• When the Current Control Switch is in either LOCAL

or REMOTE positions the arc start switch functions

when connected to the Remote receptacle.

FIGURE B.2

• Before welding with Display switch in center (normal)

position, the digital meter displays the preset welding

amps set by Maximum Output control knob (See Item

6). If in Stick mode using REMOTE (See Item 5.), the

digital meter displays the preset welding amps set by

the Remote control. (See Item 11)

REMOTE RECEPTACLE*

(Front View)

ARC START

SWITCH

REMOTE OUTPUT

CONTROL

Max

10K ohm

Min

• While welding with Display switch in center (normal)

position, the digital meter displays the actual welding

amps with one amp resolution (XXX) and accuracy

within 4%+/-2A of reading.

*For 18-12P Plug

(LECO S12020-27)

• Any time in TIG mode and while pressing the Display

switch to left, the digital meter displays the amps pre-

set by the Minimum Output control knob (See Item 7).

• Any time in Stick mode and while pressing the Display

switch to left, the digital meter displays the minimum

amps rating of the machine (See Item 7).

ADVANCED PANEL CONTROLS

The following Advanced Control Panel controls are

standard on the Precision TIG 375: (Refer to Section

B-10 Tig Weld Cycle Chart for graphic illustration of

these TIG welding functions.)

• Any time, in either mode, while pressing the Display

switch right to Volts position, the digital meter displays

actual output volts. Volts is displayed with 0.1 volt res-

olution (XX.X) and accuracy within 3%+/-1V of read-

ing.

12. TRIGGER SWITCH – This 2-position switch

selects how the arc start switch ( connected to the

above Remote receptacle) functions; in 2-Step or 4-

Step mode:

• While pressing the (Menu) button when not welding

(see Menu Button and Display Button in previous

section), for Meter and Display switch functions.

CAUTION

• DO NOT USE 4-STEP IF USING AN AMPTROL

9. POSTFLOW TIME – This knob is used to set the TIG

mode shielding gas postflow time over the range of

about 2 to 60 seconds after the arc is shut off. The

postflow on time status is indicated by the Green

panel light.

REMOTE.

• Neither the arc start switch nor the output con-

trol in the amptrol will function normally to shut

off or control the out put. ONLY USE 2-STEP.

------------------------------------------------------------------------

• In 2-Step position the arc start switch functions the

same as without the Advanced Panel:

• Postflow Time is x2 extendable, if needed, by inter-

nal control box selection. (See Internal Set Up Controls)

• Gas preflow time for TIG mode is factory set at 0.5

second, but shorter times are selectable with the

Menu Button. (See 7a.)

1. Closing switch starts preflow, then a fixed

(0.5 sec.) ramp time from Minimum (Start)

setting level (See Item 7) to Weld setting.

10. THERMAL SHUTDOWN LIGHT – This yellow LED

panel light turns on if the machine output is shut-

down because internal overheating has occurred,

and turns off when the thermostat resets.

2. Opening switch initiates Downslope ramp

time setting (See Item 17), from Weld set-

ting to Crater-fill level (See Item 7), which

then stops the arc and initiates Postflow

time (See Item 9).

11. REMOTE RECEPTACLE – A 6-socket receptacle is

provided for the connection of an Amptrol, or other,

remote control: (See Figure B.2)

Note: See Section B-7 for 2-Step operation during

Downslope with Restart feature selected to be dis-

abled, instead of enabled (as shipped).

• When the Current Control Switch, (See Item 5), is in

the REMOTE position the Amptrol, or other remote

(10K pot), connected to the Remote receptacle con-

trols the TIG or Stick mode output within the range

preset by the Maximum and Minimum Output con-

trols. (See Item 6 and Item 7, also 8 for meter dis-

play)

PRECISION TIG 375

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B-7

OPERATION

• In 4-Step position allows welding without continu-

ously holding the start switch trigger. The arc start

switch functions in the following manner:

15. PULSE % ON / SPOT TIME CONTROL –This

knob sets the time for Pulse or Spot modes:

1. Closing switch starts preflow, then arc starts

at Minimum (Start) setting level (See Item

7). If the trigger is maintained closed after

preflow time the output remains at the Start

level until it is released.

• % ON TIME sets duration of the peak current as a

percentage (5% to 95% on white scale) of one pulse

cycle. The balance of the cycle time will be at the

Background Current setting.(See Item 16)

• SPOT TIME sets the duration of the Spot pulse (0.5

2. Opening switch initiates fixed (0.5 sec.)

ramp time from Start setting level to Weld

setting.

to 5.0 seconds on red scale).

16. PULSE BACKGROUND CURRENT CONTROL –

This knob controls the level of the Background

Current as a percentage (MIN.-100%) of the Peak

(REMOTE and/or LOCAL) output level (See Item

6) down to the Minimum Output setting (See Item

7).

3. Reclosing switch initiates Downslope ramp

time setting (See item 17) from Weld setting

down to the Crater-fill level (See Item 7) of

the machine.

4. Reopening switch after Downslope time

holds Crater-fill level until switch opens,

then stops the arc and initiates the Postflow

Time (See Item 9). Or, reopening switch

during Downslope time immediately stops

the arc and initiates the Postflow.

17. DOWNSLOPE TIME– This knob is used to set the

time, over the range of zero to about 10 seconds,

to ramp down from weld setting to Crater-fill level

(See Item 7).

• If the arc goes out after the Downslope time is initi-

ated, the Downslope time is interrupted and the

Postflow time is initiated. This prevents Hi-Freq re-

initiation during ramp down crater fill

Note: See Section B-7 for 4-Step operation during

Downslope with Restart feature selected to be

enabled, instead of disabled (as shipped).

• When using an Amptrol remote control, where the

downslope is controlled by the operator down to the

crater-fill level, the Downslope time should be set to

zero so as not to have the Downslope time delay

when the arc start switch is opened.

13. PULSE / SPOT MODE SWITCH – Turns on the

Pulse Mode as indicated by the Green panel light

turning on.

• PULSE ON provides a Peak current level set by

REMOTE and/or LOCAL control of the output cur-

rent (See Item 5), for a time determined by the

Pulse Frequency Control setting (See Item 14) and

the % ON Time (See Item 15). The balance of the

cycle time is at the Background Current level (See

Item 16). The Green panel light blinks at the pulse

frequency and time setting rate.

18.HIGH FREQUENCY INTENSITY CONTROL (NOT

SHOWN)– Allows setting the lowest intensity which

still gives good TIG arc starting with minimized

Radio Frequency Interference (RFI). Control knob

is located on a recessed panel near the easy acces-

sible spark gap side panel. As shipped, the control

is set to minimum.

• Pulsing begins after upslope when the output cur-

rent rises above the Background Current level and

ends when the output current drops below this level.

• SPOT ON mode provides the peak current level set

by the Maximum Output Control for a time deter-

mined by the SPOT TIME control (see below). The

red panel light is on for Spot mode.

14. PULSE FREQUENCY CONTROL – This knob is

used to set the Pulse Frequency over the peak

pulse range of about 0.1 pps to 20 pps. (One pulse

cycle time = 1/pps = 10 to .05 sec. range.)

PRECISION TIG 375

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B-8

OPERATION

INTERNAL SET UP CONTROLS

TIG WELDING FEATURES

Precision TIG 375 Advanced Panel has the following

additional control features which are set up using the

DIP Switch (S1) provided on the internal panel of this

option.

The following DIP switch feature selections function

only when the Precision TIG is set to TIG mode (See

Item 3):

• Switch #1 Postflow Time Extension* (See Item 9)

Access to this internal panel is obtained by removing

the two screws securing the top corners of the

Precision TIG front control panel and swinging the con-

trol panel down to reveal the panel mounted on the sur-

face of the Precision TIG Control board:

ON – Doubles the time ranges.

OFF – Standard time range (as shipped).

• Switch #2 2-Step Trigger Restart Feature (See

Figure B.3)

CAUTION

ON – Restart Enabled (as shipped).

• THE CONTROL BOARDS CONTAIN STATIC SEN-

SITIVE COMPONENTS

OFF – Restart Disabled.

• To avoid possible damage to these components

be sure to ground yourself by touching the

machineʼs sheet metal while handling or making

settings on the internal control box components.

------------------------------------------------------------------------

PRECISION TIG ADVANCED PANEL

• Switch #3 4-Step Trigger Restart Feature (See

Figure B.4)

ON – Restart Enabled.

OFF – Restart Disabled (as shipped)

(M21115 Internal Panel)

• Switch #4 Lift TIG Starting - Does not function

(See Item 7a)

• Switch #5 Crater-Fill Level (See Item 7)

^ ON

1 2 3 4 5 6 7

ON - Level is minimum rating of the machine (2A)

OFF – Level (as shipped) is Minimum Output setting

(same as Start level).

DIP SWITCH (S1)

(DOES NOT FUNCTION)

HOT START

ARC FORCE

OFF

DIP SWITCH POSITIONS (FACTORY SETTINGS)

STICK WELDING FEATURES

• Switch #6 Hot Start Level – Does not function

(See Item 7a)

• Switch #7 Arc Force Level – Does not function

(See Item 7a)

PRECISION TIG 375

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B-9

OPERATION

FIGURE B.3

(With DIP Switch #2 OFF)

(With DIP Switch #2 ON, As Shipped)

PRECISION TIG 375

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B-10

OPERATION

FIGURE B.4

(With DIP Switch #3 ON)

(With DIP Switch #3 OFF, As Shipped)

PRECISION TIG 375

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B-11

OPERATION

TIG WELD CYCLE CHART

SEE ITEM 12

SEE ITEM 7a

SEE ITEM 6

SEE ITEM 6 & 7

SEE ITEM 7

SEE ITEM 15

SEE ITEM 14

SEE ITEM 7

SEE ITEM 15

SEE ITEM 7a

SEE ITEM 9

SEE ITEM 7a

SEE ITEM 16

SEE ITEM 17

SEE ITEM 12

SEE ITEM 12 & TIG

Welding Features

SETUP GUIDELINES FOR TIG WELDING

WITH AN AMPTROL

Both the Hand and Foot Amptrols work in a similar

manner. They are meant to be used for remote current

control for TIG welding using the machineʼs 2-Step

trigger mode (See Item 12).

The Amptrol is capable of controlling the output of the

Precision TIG over the range between the level preset

by the Minimum Output control when the Amptrol is at

its inactivated state, and the level preset by the

Maximum Output control when the Amptrol is at fully-

activated state.

It is important to note that even with the Precision TIGʼs

new MicroStart Technology, some tungstens may be

difficult to start at the low (2 amps) minimum rating of

the machine. Rather than guessing where to depress

the Amptrol to start the arc reliably, the Minimum

Output control allows presetting the exact level, so

reliable starts, as well as minimum crater-fill levels, can

be consistently obtained at the minimum Amptrol (inac-

tivated ) state. FIGURE B.6 shows Precision TIG setup

for TIG welding with an Amptrol.

PRECISION TIG 375

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B-12

OPERATION

FIGURE B.6

Standard Controls

Setup for TIG Amptrol Welding

Power Switch

Mode Switch

TIG

Polarity Switch

AC Balance

AUTO

AC or DC-

Set:

More +

for alum.oxide "Cleaning"

w/o"Spitting" o r"wetting"loss.

Balanced for equal and current.

More - for higher "Penetration".

Local/Remote

Switch

REMOTE

Maximum Output

Set to desired max.

Amptrol output level.

Minimum Output

Press Display switch

and Set to desired min.

Amptrol (Start/Crater)

output level.

Min. to Max.

Amptrol

Max. to Min.

Amptrol

Postflow

Set as low as required.

Higher for larger

tungsten and current.

Advanced Panel

(If used)

Trigger Switch

2-STEP

Pulse Frequency

Pulse Switch

4-6 pps is a typical initial setting.

Set for bead shape and travel speed:

Higher for thinner plate and faster travel.

Lower for thicker plate and slower travel.

OFF

% On Time

40-60% is a typical initial setting.

Set for total heat of Peak current:

Lower reduces distortion and burn-thru.

Background Current

40-60% is a typical initial setting.

Set as low as will maintain a pulse arc

Downslope

ZERO

For no arc-out delay.

Min.Output

(Will not drop below

setting.)

PRECISION TIG 375

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B-13

OPERATION

Close the arc start switch. This opens the gas valve

to automatically purge air from the hose and torch,

then shields the arc strike area. After the 0.5 sec-

ond preflow time, the high frequency becomes

available to strike the arc. When the arc strikes the

torch coolant (if used) starts to flow. Also, if welding

DC- TIG, the high frequency shuts off just after the

arc strikes.

MAKING A TIG WELD WITH AN AMPTROL

1. Install welding equipment per Section A-5.

2. Setup controls per Section B-10.

3. Turn on the shielding gas supply, and torch coolant

input supply (if used).

Note: The Precision TIG Under-Cooler (or Water

Solenoid connected to the Cooler receptacle) runs with

the Fan-As-Needed machine cooling fan (See

Maintenance Section D), so the cooler fan and water

pump will also not run continuously in idle, but will run

while welding.

6. Hold the arc start switch closed at minimum Amptrol

Start level (See Section B-10) until an arc is estab-

lished, then increase the output to the desired welding

level and push the torch in the direction of travel.

7. At the end of the weld, decrease the Amptrol output

to the crater-fill level before releasing the arc start

switch to start the Postflow time. Hold the torch gas

shielding over the solidifying weld crater while post-

flow time expires and the gas valve reopens. The

torch coolant (if used) continues to flow for up to 8

minutes after the arc goes out (with the Fan-As-

Needed feature) to assure torch cooling.

4. With the torch held safely away from everything,

close the Arc Start Switch of the Amptrol and set the

gas flow meter. Then open the switch. The welder

is now ready for welding.

5. Position the tungsten electrode at the start of the

weld at a 65° to 75° angle with the horizontal, in the

direction of pushing travel, so that the electrode is

approximately 1/8" (4 mm) above the work piece.

• Repeat steps 5 through 7 to make another weld.

RECOMMENDED ELECTRODE AMPERAGE RANGES - Precision TIG 375

SMAW Process

ELECTRODE

Fleetweld 5P, Fleetweld 5P+

Fleetweld 180

POLARITY

DC+

3/32"

40 - 70

40 - 80

70 - 95

75 - 95

85 - 110

40 - 80

40 - 70

1/8"

5/32"

75 - 130

55 - 110

100 - 135

100 - 145

110 - 160

75 - 110

60 - 100

90 - 175

105 - 135

145 - 180

135 - 200

130 - 220

95 - 110

90 - 140

DC+

Fleetweld 37

DC+

Fleetweld 47

DC-

Jet-LH MR

DC+

Blue Max Stainless

Red Baron Stainless

DC+

Mild steel procedures are based on recommended procedures listed in C2.10 8/94 and the maximum rating of the Precision TIG 375

Excaliber 7018 procedures are based on Jet-LH 78 MR

Blue Max procedures are based on C6.1 6/95

Red Baron Procedure are based on ES-503 10/93

GTAW Process

Electrode Polarity

DC-

AC*

Approximate Argon

Gas Flow Rate

C.F.H. (l/min.)

Electrode Tip Preparation

Sharpened

Balled

EWZr

Electrode Type

EWTh-1, EWCe-2

EWTh-2, EWLa-1

EWG

EWTh-1, EWTh-2

EWCe-2, EWLa-1

EWG

EWP

Stainless

Steel

Electrode Size (in.)

Aluminum

.010

.020

.040

1/16

3/32

1/8

Up to 15 A.

Up to 80 A.

Up to 150 A.

Up to MAX. A.

Up to 15 A.

10 to 15 A.

20 to 30 A.

30 to 80 A.

60 to 130 A.

100 to 180 A.

Up to 15 A.

3-8

(2-4) 3-8

(2-4)

5 to 20 A.

5-10

(3-5) 5-10 (3-5)

(3-5) 9-13 (4-6)

20 to 60 A.

60 to 120 A.

100 to 180 A.

160 to 250 A.

13-17 (6-8) 11-15 (5-7)

15-23 (7-11) 11-15 (5-7)

Tungsten electrodes are classified as follows by the American Welding Society (AWS):

Pure.........................................EWP...........green

+1% Thoria..............................EWTh-1......yellow

+2% Thoria..............................EWTh-2......red

+2% Ceria................................EWCe-2 .....orange

+1.5% Lanthana ......................EWLa-1......black

+0.15 to 0.40% Zirconia ..........EWZr..........brown

Ceriated Tungsten is now widely accepted as a substitute for 2% Thoriated Tungsten in AC and DC applications.

^{Balanced Wave, Unbalanced Wave requires derating of the ele}P^ctrR^odeE^.CISION TIG 375

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C-1

ACCESSORIES

OPTIONAL EQUIPMENT

FACTORY INSTALLED OPTIONS

• K963-3 Hand Amptrol

Fastens to torch for convenient thumb activation of

arc start switch and output control, with 25ʼ plug

cable.

The basic Precision TIG 375 machine is factory

equipped with:

• K814 Arc Start Switch

• K2621-1 Precision TIG Advanced Control Panel.

Provides 2/4-step trigger with adjustable Pulser con-

trols and Down slope timer for TIG welding. Also

includes adjustable Hot Start and Arc Force internal

panel controls for stick welding and other user selec-

table features.

Needed for TIG welding without an Amptrol. Includes

25ʼ plug cable, and attaches to torch for convenient

finger control.

• Magnum® PTA and PTW Series Torches

All Air Cooled or Water-Cooled Magnum® TIG

Torches may be used with the Precision TIG 375.

Connection adapters are only required for Air-Cooled

Torches (Refer to Diagrams on A-7):

• Power Factor correction capacitor.

• A 3/8" Adapter (S20403-4) for air cooled torch con-

nection.

Accessories that are factory installed with the

Domestic model (K2622-1) to make up the Domestic

Welding Package (K2624-1) include:

K2166-1 7/8” Torch Connector for PTA-26 (one

piece)

K2166-2 1/2” stud Connector for PTA Torch (two-

piece).

• K1828-1

• 3100211

Under-Cooler Cart

Harris Argon Flow Regulator with 10ʼ

hose.

K2166-3 3/8” TIG Torch Connector for PTA-9,-17

(one piece). (Included as S20403-4 with Precision

TIG models.)

• K870

Foot Amptrol

• K1784-4

• K918-2

• KPi510

• K2150-1

25ʼ PTW-20 water-cooled TIG Torch

Zippered Torch Cover

Parts Kit for Torch

• 3100211 Harris Argon Flow Regulator (Includes 10ʼ

hose.)

Work Lead Assembly

See below for more detailed descriptions.

• K2150-1 Work Lead Assembly

FIELD INSTALLED OPTIONS

15ft. 2/0 cable with 1/2" stud lug and work clamp.

The following Options/Accessories are available for the

Precision TIG 375 and are installed per instructions in

this manual and / or provided in the package:

• K1828-1 Under-Cooler Cart

Includes a "cooler-in-a-drawer" with hoses and a

lockable storage drawer on a dual bottle undercar-

riage (see below).

• K1869-1 Undercarriage

Includes a dual bottle rack with chain and an under-

carriage with 5" front casters,10" rear wheels and a

handle.

• K1830-1 Water Solenoid Kit

Provides for stopping flow of external water supply.

Connects to coolant inlet and cooler receptacle of

Precision TIG.

(Can not be used with a water cooler.)

• K870 Foot Amptrol

Single pedal foot activation of arc start switch and

output control, with 25ʼ plug cable.

PRECISION TIG 375

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D-1

MAINTENANCE

SAFETY PRECAUTIONS

OVERLOAD PROTECTION

FAN-AS-NEEDED (F.A.N.)

WARNING

The Precision TIG 375 has the F.A.N. circuit feature,

which means the cooling fan will operate only while

welding; then for about 8 minutes after welding has

stopped to assure proper machine cooling. This helps

reduce the amount of dust and dirt drawn into the

machine with the cooling air. The cooling fan will oper-

ate briefly when the machine power is initially turned

on, and continuously while the yellow Thermal

Shutdown Light is lit (see Thermostatic Protection).

ELECTRIC SHOCK can kill.

• Only qualified personnel should

perform this maintenance.

• Turn the input power OFF at the

disconnect switch or fuse box

before working on this

equipment.

• Do not touch electrically hot

parts.

THERMOSTATIC PROTECTION

This welder has thermostatic protection from excessive

duty cycles, overloads, loss of cooling, and excessive

ambient temperatures. When the welder is subjected

to an overload, or inadequate cooling, the primary coil

thermostat and/or secondary coil thermostat will open.

This condition will be indicated by the illumination of

the yellow Thermal Shutdown Light on the front panel

(see Item 10 in Section B). The fan will continue to run

to cool the power source. Postflow occurs when TIG

welding is shut down, but no welding is possible until

the machine is allowed to cool and the yellow Thermal

Shutdown Light goes out.

WARNING

To avoid receiving a high frequency shock, keep

the TIG torch and cables in good condition.

ROUTINE AND PERIODIC MAINTENANCE

Very little routine maintenance is necessary to keep

your Precision TIG 375 running in top condition. No

specific schedule can be set for performing the follow-

ing items; factors such as hours of usage and machine

environment should be considered when establishing

a maintenance schedule.

NO ARC PROTECTION

The machine outputs (Background / OCV, gas and HF)

will be shutdown, if the trigger is closed without weld-

ing for 15 seconds to protect the Background resistor

from overheating with F.A.N. cooling off, as well as to

conserve on gas waste.

• Periodically blow out dust and dirt which may accu-

mulate within the welder using an air stream.

• Inspect welder output and control cables for fraying,

cuts, and bare spots.

AUXILIARY POWER CIRCUIT BREAKER

• Inspect the spark gap at regular intervals to maintain

the recommended spacing. See the Service

Procedures (See Service Procedures in this

Section) for complete information on spark gap set-

tings.

The 115vac auxiliary circuits and rear receptacle (see

Section A Auxiliary Power Connections) are protected

from overloads by a 15 amp circuit breaker, located

above the receptacle. If the breaker trips its button

pops out exposing a red ring. When the circuit breaker

cools the button can be reset by pressing it back in.

Note: When the breaker trips not only will the recepta-

cleʼs auxiliary and cooler power be interrupted, but so

will the power to the shielding gas solenoid and

machine cooling fan.

• The fan motor has sealed ball bearings which

require no maintenance.

The Export models also include a 5 amp circuit break-

er, located on the opposite side of the upper case back,

for protection of the 220vac Schuko type cooler recep-

tacle.

PRECISION TIG 375

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D-2

MAINTENANCE

FIGURE C.1 SPARK GAP

SERVICE PROCEDURES

Operation of the Precision TIG should be trouble-free

for the life of the machine. Should a malfunction occur,

however, the following procedures will be useful to

trained service personnel with experience in repairing

arc welding equipment:

.015 Spark Gap

COMPONENT ACCESS

Note: In highly dirty environments where there is an

abundance of conductive contaminants, use a low

pressure air stream or a firm piece of paper to clean

out the spark gap. Do not disturb the factory gap set-

ting.

The following components are accessible for routine

set up and periodic service without requiring removal

of the case sides or roof:

• Input Reconnect Panel (refer Section A) is located

behind a removable panel on the rear of the left case

side. Remove the two screws (with a screwdriver or

a 3/8"/ 9.5mm hex driver) on the bottom corners of

this panel to remove it.

To check the spark gap:

1. Turn the input power off per above.

2. Remove the access panel on the right case side

(See Component Access).

3. Check the spark gap spacing with a feeler gauge.

• Control Box components and PC Boards (refer

Section B-6) are located behind the front control

panel. Remove the two screws (with a screwdriver or

a 3/8"/ 9.5mm hex driver) on the top corners of this

panel to swing it down.

If adjustment is required:

1. Adjust the gap by loosening the Allen head screw

on one of the aluminum blocks, reset the gap and

tighten the screw in the new position.

• Hi-Freq. Spark Gap assembly (refer Spark Gap

Adjustment) is located behind a removable panel on

the rear of the right case side, under the torch box.

Remove the screw (with a screwdriver or a 3/8"/

9.5mm hex driver) on the bottom center of this panel

to remove it.

If spark gap is correct:

1. Reinstall the access panel on the right case side.

UNDER-COOLER SERVICE

The required maintenance and service instructions for

the Under-Cooler are provided in the operatorʼs manu-

al (IM723) provided with the Under-Cooler Cart.

SPARK GAP ADJUSTMENT

The spark gap is set at the factory to a gap of 0.015

inches (0.4 mm) See Figure C.1. This setting is ade-

quate for most applications. Where less high frequen-

cy is desired, the setting can be reduced to 0.008 inch-

es (0.2 mm).

WARNING

Use extreme caution when working with circuit of

the high frequency. The high voltages developed

can be lethal. Turn the input power off using the

disconnect switch or fuse box before working

inside the machine. This is particularly important

when working on the secondary circuit of the high

voltage transformer (T3) because the output volt-

age is dangerously high.

------------------------------------------------------------------------

PRECISION TIG 375

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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.

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).

If you do not understand or are unable to perform the

Recommended Course of Action safely, contact your

local Lincoln Authorized Field Service Facility.

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.

Step 2. POSSIBLE CAUSE.

The second column labeled “POSSIBLE CAUSE” lists

the obvious external possibilities that may contribute to

the machine symptom.

Step 3. RECOMMENDED COURSE OF ACTION

CAUTION

DO NOT use a volt-ohm meter to measure output voltages in TIG mode. The

High Frequency Arc Starter voltage can damage the meter.

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.

PRECISION TIG 375

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E-2

TROUBLESHOOTING

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

POSSIBLE

RECOMMENDED

(SYMPTOMS)

CAUSE

COURSE OF ACTION

OUTPUT PROBLEMS

Thermal light comes on

1. Thermal shut down. Dirt and dust

may have clogged the cooling

channels inside machine; air

intake and exhaust louvers may

be blocked.; welding application

may exceed recommended duty

cycle. Wait until machine cool

down and thermal light goes out.

Blow out machine with clean, dry

low pressure air; check air intake

and louvers; stay within recom-

mended duty cycle.

2. Bad thermostat or its connections

Meter doesnʼt light up

1. Losing AC supply to Control PC

board

2. Loosing input to machine

3. Faulty Control PC board

If all recommended possible areas

of misadjustment have been

checked and the problem persists,

Has output in

Stick mode

No gas & no hi-freq 1. Faulty trigger or hand/foot Amptrol

or connections.

Contact

your

local

Lincoln

Authorized Field Service Facility.

but no output

in Tig mode

2. Faulty Protection PC board or

bad connection to Control PC

board

3. Losing trigger supply to Control

PC board

Gas & hi-freq are o.k. 1. Faulty Control PC board

No output in both Stick and Tig

modes

1. Bad connection at P4 of Control

PC board

2. Faulty Control PC board

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.

PRECISION TIG 375

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E-3

TROUBLESHOOTING

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

POSSIBLE

RECOMMENDED

(SYMPTOMS)

CAUSE

COURSE OF ACTION

METER PROBLEMS

Meter does not light up

1. Bad meter or its connection.

2. Bad connection at P8 of Control

PC board.

If all recommended possible areas

of misadjustment have been

checked and the problem persists,

3. Faulty Control PC board.

Contact

your

local

Lincoln

Authorized Field Service Facility.

Meter does not display V (Volt) or

Min A (Minimum current)

1. Bad Display switch or its connec-

tion.

2. Bad connection at P9 of Control

PC board.

GAS PROBLEMS

1. Circuit breaker CB1 open. Press

CB1 in to reset.

No gas

2. Bad connection at P12 of Control

PC board.

3. Faulty gas solenoid valve SV1 or

its connection.

4. Faulty Control PC board.

No control on post flow time

1. Faulty potentiometer R3 or its

connection.

If all recommended possible areas

of misadjustment have been

checked and the problem persists,

2. Bad connection at P9 of Control

PC board.

Contact

your

local

Lincoln

Pre flow & Post flow time too long

1. For Postflow; the DIP switch set-

ting on the Advanced Control

PCB (if installed) may be set for

time x2.

Authorized Field Service Facility.

2. For Preflow; Menu setting too

long.

3. Missing plug P3 on Control board

or bad connection at P3 when an

Advanced Control PC board is not

present.

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.

PRECISION TIG 375

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E-4

TROUBLESHOOTING

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

POSSIBLE

RECOMMENDED

(SYMPTOMS)

CAUSE

COURSE OF ACTION

HI-FREQ PROBLEMS

No hi-freq

1. Circuit breaker CB1 open

2. Bad connection at P12 of Control

PC board

3. Spark gaps shorted

4. Faulty Control PC board

Hi-freq intensity too weak

1. Dirty spark gap or improper gap

setting

2. Faulty Arc Starter assembly

Hi-freq on continuously in DC Tig

1. Bad connection at P11 of Control

PC board

2. Micro-switch S2A is not engaged &

disengaged properly when switch-

ing between DC & AC polarity.

(S2A locates on the Polarity

switch)

If all recommended possible areas

of misadjustment have been

checked and the problem persists,

3. Faulty Control PC board

Contact

your

local

Lincoln

Authorized Field Service Facility.

Hi-freq shuts off after starting in AC 1. Micro-switch S2A is not engaged &

Tig

disengaged properly when switch-

ing between DC & AC polarity.

(S2A locates on the Polarity

switch)

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.

PRECISION TIG 375

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E-5

TROUBLESHOOTING

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

POSSIBLE

RECOMMENDED

(SYMPTOMS)

CAUSE

COURSE OF ACTION

PRESET & OUTPUT CONTROL PROBLEMS

Meter does not display preset

1. Faulty potentiometer R1 or its con-

nection

2. Bad connection at P9 of Control

PC board

3. Faulty Advanced Control PC board

( if present ) or its connection to

the main Control PC board

4. Missing plug P3 on Control board

or bad connection at P3 when an

Advanced Control PC board is not

present

High output current in both DC & AC 1. Bad connection at P6 of Control

polarities regardless of preset

PC board

2. Bad shunt connection

3. Faulty Control PC board

4. Faulty SCR bridge

If all recommended possible areas

of misadjustment have been

checked and the problem persists,

Contact

your

local

Lincoln

High output current in DC polarity 1. Shorted free wheeling diode D1

Authorized Field Service Facility.

regardless of preset, o.k. in AC polar-

ity

In 2-step Tig, output stays on for 1. Bad 2/4 step switch or its connec-

more than downslope time after trig-

ger open (machine with Advanced

Control panel only)

tion

2. Bad connection at P1 of Advanced

Control PC board

Output stays on after releasing 1. Downslope is not set at min.

hand/foot Amptrol (machine with

Advanced Control panel only)

2. Bad Downslope potentiometer

R12 or its connection

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.

PRECISION TIG 375

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E-6

TROUBLESHOOTING

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

POSSIBLE

RECOMMENDED

(SYMPTOMS)

CAUSE

COURSE OF ACTION

STICK WELDING PROBLEMS

Stick electrode "blast off" when arc 1. Current may be set too high for

is struck

electrode size

2. (Machine with Advanced Control If all recommended possible areas

PC board only) Hot Start Menu of misadjustment have been

setting too high

checked and the problem persists,

Contact

your

local

Lincoln

Stick electrode "sticks" in the weld

puddle

1. Current may be set too low for Authorized Field Service Facility.

electrode size

2. (Machine with Advanced Control

PC board only) Arc Force Menu

setting too low

TIG WELDING PROBLEMS

Poor starting in DC polarity

1. Input line may be too low

2. Bad connection at P11 of Control

PC board

3. Bad Background rectifier, back-

ground resistor R7, or background

diode D2

Arc "flutters" in DC polarity, o.k. in

AC polarity

1. Tungsten not "sharp"

2. Bad free wheeling diode D1 or its

connection

If all recommended possible areas

of misadjustment have been

Arc "flutters" in both DC & AC polari- 1. Tungsten electrode may be too checked and the problem persists,

ties

large in diameter for the current Contact

your

local

Lincoln

setting

Authorized Field Service Facility.

2. Gas shielding may be insufficient.

3. Contaminated gas or leaks in the

gas line, torch, or connections

4. Helium blend is used as a shield-

ing gas

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.

PRECISION TIG 375

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E-7

TROUBLESHOOTING

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

POSSIBLE

RECOMMENDED

(SYMPTOMS)

CAUSE

COURSE OF ACTION

TIG PROBLEMS

Arc "pulsates" in AC polarity, DC 1. Micro switch S2A on polarity switch

polarity is o.k.

does not open in AC polarity

Black area along weld bead

1. Oily or organic contamination from

work piece

2. Tungsten electrode may be conta-

minated

3. Leaks in gas line, torch, or con-

nections

Output quits momentarily; gas flow 1. May be caused by hi-freq interfer-

and hi-freq are also interrupted

ence. Check that machine is

grounded properly. Surrounding

machines that generate hi-freq

also should be properly grounded.

2. Ground connection of Protection

PC board may has become loose

If all recommended possible areas

of misadjustment have been

checked and the problem persists,

3. Ground connection of Bypass

/Stabilizer PC board may has

become loose.

Contact

your

local

Lincoln

Authorized Field Service Facility.

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.

PRECISION TIG 375

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F-1

WIRING DIAGRAM

PRECISION TIG 375

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F-2

WIRING DIAGRAM

PRECISION TIG 375

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F-3

DIMENSION PRINT

PRECISION TIG 375

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F-4

DIMENSION PRINT

PRECISION TIG 375

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● Do not touch electrically live parts or ● Keep flammable materials away.

● Wear eye, ear and body protection.

electrode with skin or wet clothing.

● Insulate yourself from work and

ground.

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’entretien.

● N’opérez pas avec les panneaux

ouverts ou avec les dispositifs de

protection enlevés.

● Gardez la tête à l’écart des fumées.

● Utilisez un ventilateur ou un aspira-

teur pour ôter les fumées des zones

de travail.

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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