Lincoln Electric SVM169-A User Manual

PRECISION TIG 185

SVM169-A

July, 2006

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.

SERVICE MANUAL

For use with machines having Code Number : 11105 thru 11109

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i

SAFETY

i

PRECISION TIG 185

FOR ENGINE
powered equipment.

1.a. Turn the engine off before troubleshooting and maintenance
work unless the maintenance work requires it to be running.

____________________________________________________

1.b.Operate engines in open, well-ventilated
areas or vent the engine exhaust fumes
outdoors.

____________________________________________________

1.c. Do not add the fuel near an open flame weld­ing arc or when the engine is running. Stop
the engine and allow it to cool before refuel­ing to prevent spilled fuel from vaporizing on
contact with hot engine parts and igniting. Do
not spill fuel when filling tank. If fuel is spilled,
wipe it up and do not start engine until fumes
have been eliminated.

____________________________________________________

1.d. Keep all equipment safety guards, covers and devices in posi­tion and in good repair.Keep hands, hair, clothing and tools
away from V-belts, gears, fans and all other moving parts
when starting, operating or repairing equipment.

____________________________________________________

1.e. In some cases it may be necessary to remove safety

guards to perform required maintenance. Remove
guards only when necessary and replace them when the
maintenance requiring their removal is complete.
Always use the greatest care when working near moving
parts.

___________________________________________________

1.f. Do not put your hands near the engine fan.
Do not attempt to override the governor or
idler by pushing on the throttle control rods
while the engine is running.

___________________________________________________

1.g. To prevent accidentally starting gasoline engines while
turning the engine or welding generator during maintenance
work, disconnect the spark plug wires, distributor cap or
magneto wire as appropriate.

ARC WELDING CAN BE HAZARDOUS. PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH.
KEEP CHILDREN AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.

Read and understand the following safety highlights. For additional safety information, it is strongly recommended that you
purchase a copy of “Safety in Welding & Cutting - ANSI Standard Z49.1” from the American Welding Society, P.O. Box 351040,
Miami, Florida 33135 or CSA Standard W117.2-1974. AFree copy of “Arc Welding Safety” booklet E205 is available from the
Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, Ohio 44117-1199.

BE SURE THAT ALL INSTALLATION, OPERATION, MAINTENANCE AND REPAIR PROCEDURES ARE
PERFORMED ONLY BY QUALIFIED INDIVIDUALS.

WARNING

Mar ‘95

ELECTRIC AND
MAGNETIC FIELDS
may be dangerous

2.a. Electric current flowing through any conductor causes
localized Electric and Magnetic Fields (EMF). Welding
current creates EMF fields around welding cables and
welding machines

2.b. EMF fields may interfere with some pacemakers, and
welders having a pacemaker should consult their physician
before welding.

2.c. Exposure to EMF fields in welding may have other health
effects which are now not known.

2.d. All welders should use the following procedures in order to
minimize exposure to EMF fields from the welding circuit:

2.d.1.

Route the electrode and work cables together - Secure
them with tape when possible.

2.d.2. Never coil the electrode lead around your body.

2.d.3. Do not place your body between the electrode and

work cables. If the electrode cable is on your right
side, the work cable should also be on your right side.

2.d.4. Connect the work cable to the workpiece as close as

possible to the area being welded.

2.d.5. Do not work next to welding power source.

1.h. To avoid scalding, do not remove the
radiator pressure cap when the engine is
hot.

CALIFORNIA PROPOSITION 65 WARNINGS

Diesel engine exhaust and some of its constituents
are known to the State of California to cause can­cer, birth defects, and other reproductive harm.

The engine exhaust from this product contains
chemicals known to the State of California to cause
cancer, birth defects, or other reproductive harm.

The Above For Diesel Engines

The Above For Gasoline Engines

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ii

SAFETY

ii

PRECISION TIG 185

ARC RAYS can burn.

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.

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.

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.

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.

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:

• Semiautomatic DC Constant Voltage (Wire) Welder.

• DC Manual (Stick) Welder.

• AC Welder with Reduced Voltage Control.

3.c. In semiautomatic or automatic wire welding, the electrode,
electrode reel, welding head, nozzle or semiautomatic
welding gun are also electrically “hot”.

3.d. Always be sure the work cable makes a good electrical
connection with the metal being welded. The connection
should be as close as possible to the area being welded.

3.e. Ground the work or metal to be welded to a good electrical
(earth) ground.

3.f.

Maintain the electrode holder, work clamp, welding cable and
welding machine in good, safe operating condition. Replace
damaged insulation.

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

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.

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.

FUMES AND GASES
can be dangerous.

5.a.Welding may produce fumes and gases
hazardous to health. Avoid breathing these
fumes and gases.When welding, keep
your head out of the fume. Use enough
ventilation and/or exhaust at the arc to keep

fumes and gases away from the breathing zone. When

welding with electrodes which require special
ventilation such as stainless or hard facing (see
instructions on container or MSDS) or on lead or
cadmium plated steel and other metals or coatings
which produce highly toxic fumes, keep exposure as
low as possible and below Threshold Limit Values (TLV)
using local exhaust or mechanical ventilation. In
confined spaces or in some circumstances, outdoors, a
respirator may be required. Additional precautions are
also required when welding on galvanized steel.

5.b.

Do not weld in locations near chlorinated hydrocarbon

vapors
coming from degreasing, cleaning or spraying operations.
The heat and rays of the arc can react with solvent vapors

to
form phosgene, a highly toxic gas, and other irritating prod­ucts.

5.c. Shielding gases used for arc welding can displace air and
cause injury or death. Always use enough ventilation,
especially in confined areas, to insure breathing air is safe.

5.d. Read and understand the manufacturer’s instructions for this

equipment and the consumables to be used, including the
material safety data sheet (MSDS) and follow your
employer’s safety practices. MSDS forms are available from
your welding distributor or from the manufacturer.

5.e. Also see item 1.b.

Mar ‘95

PRECISION TIG 185

SAFETY

iii iii

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FOR ELECTRICALLY
powered equipment.

8.a. Turn off input power using the disconnect
switch at the fuse box before working on
the equipment.

8.b. Install equipment in accordance with the U.S. National
Electrical Code, all local codes and the manufacturer’s
recommendations.

8.c. Ground the equipment in accordance with the U.S. National
Electrical Code and the manufacturer’s recommendations.

CYLINDER may explode
if damaged.

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

pressure used. All hoses, fittings, etc. should be suitable for
the application and maintained in good condition.

7.b. Always keep cylinders in an upright position securely
chained to an undercarriage or fixed support.

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.

7.d. Never allow the electrode, electrode holder or any other
electrically “hot” parts to touch a cylinder.

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.

Mar ‘95

WELDING 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.

Remember that welding sparks and hot
materials from welding can easily go through small cracks
and openings to adjacent areas. Avoid welding near
hydraulic lines. Have a fire extinguisher readily available.

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.

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.

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).

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.

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.

6.h. Also see item 1.c.

PRECISION TIG 185

SAFETY

iv iv

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PRÉCAUTIONS DE SÛRETÉ

Pour votre propre protection lire et observer toutes les instructions
et les précautions de sûreté specifiques qui parraissent dans ce
manuel aussi bien que les précautions de sûreté générales suiv­antes:

Sûreté Pour Soudage A L’Arc

1. Protegez-vous contre la secousse électrique:

a. Les circuits à l’électrode et à la piéce sont sous tension

quand la machine à souder est en marche. Eviter toujours
tout contact entre les parties sous tension et la peau nue
ou les vétements mouillés. Porter des gants secs et sans
trous pour isoler les mains.

b. Faire trés attention de bien s’isoler de la masse quand on

soude dans des endroits humides, ou sur un plancher met­allique ou des grilles metalliques, principalement dans
les positions assis ou couché pour lesquelles une grande
partie du corps peut être en contact avec la masse.

c. Maintenir le porte-électrode, la pince de masse, le câble de

soudage et la machine à souder en bon et sûr état defonc­tionnement.

d.Ne jamais plonger le porte-électrode dans l’eau 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 s’applicuent aussi au pistolet de
soudage.

2. Dans le cas de travail au dessus du niveau du sol, se protéger
contre les chutes dans le cas ou on recoit un choc. Ne jamais
enrouler le câble-électrode autour de n’importe quelle partie du
corps.

3. Un coup d’arc peut être plus sévère qu’un coup de soliel, donc:

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

qu’un verre blanc afin de se protéger les yeux du rayon­nement de l’arc et des projections quand on soude ou
quand on regarde l’arc.

b. Porter des vêtements convenables afin de protéger la peau

de soudeur et des aides contre le rayonnement de l‘arc.

c. Protéger l’autre personnel travaillant à proximité au

soudage à l’aide d’écrans appropriés et non-inflammables.

4. Des gouttes de laitier en fusion sont émises de l’arc de
soudage. Se protéger avec des vêtements de protection libres
de l’huile, tels que les gants en cuir, chemise épaisse, pan­talons sans revers, et chaussures montantes.

5. Toujours porter des lunettes de sécurité dans la zone de
soudage. Utiliser des lunettes avec écrans lateraux dans les

zones où l’on pique le laitier.

6. Eloigner les matériaux inflammables ou les recouvrir afin de
prévenir tout risque d’incendie dû aux étincelles.

7. Quand on ne soude pas, poser la pince à une endroit isolé de
la masse. Un court-circuit accidental peut provoquer un
échauffement et un risque d’incendie.

8. S’assurer que la masse est connectée le plus prés possible de
la zone de travail qu’il est pratique de le faire. Si on place la
masse sur la charpente de la construction ou d’autres endroits
éloignés de la zone de travail, on augmente le risque de voir
passer le courant de soudage par les chaines de levage,
câbles de grue, ou autres circuits. Cela peut provoquer des
risques d’incendie ou d’echauffement des chaines et des
câbles jusqu’à ce qu’ils se rompent.

9. Assurer une ventilation suffisante dans la zone de soudage.
Ceci est particuliérement important pour le soudage de tôles
galvanisées plombées, ou cadmiées ou tout autre métal qui
produit des fumeés toxiques.

10. Ne pas souder en présence de vapeurs de chlore provenant
d’opérations de dégraissage, nettoyage ou pistolage. La
chaleur ou les rayons de l’arc peuvent réagir avec les vapeurs
du solvant pour produire du phosgéne (gas fortement toxique)
ou autres produits irritants.

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.

PRÉCAUTIONS DE SÛRETÉ POUR
LES MACHINES À SOUDER À
TRANSFORMATEUR ET À
REDRESSEUR

1. Relier à la terre le chassis du poste conformement au code de
l’électricité et aux recommendations du fabricant. Le dispositif
de montage ou la piece à souder doit être branché à une
bonne mise à la terre.

2. Autant que possible, I’installation et l’entretien du poste seront
effectués par un électricien qualifié.

3. Avant de faires des travaux à l’interieur de poste, la debranch­er à l’interrupteur à la boite de fusibles.

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

PRECISION TIG 185

vv

MASTER TABLE OF CONTENTS FOR ALL

SECTIONS

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i-iv

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

Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section B

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section C

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section D

Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section E

Troubleshooting and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section F

Electrical Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Section G

Parts Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .P499 Series

RETURN TO MAIN MENU

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PRECISION TIG 185

Section A-1 Section A-1

TABLE OF CONTENTS

- INSTALLATION SECTION -

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

Technical Specifications.....................................................................................A-2/A-3

Safety Precautions ....................................................................................................A-4

Location.....................................................................................................................A-4

Grinding ..............................................................................................................A-4

Stacking ..............................................................................................................A-4

Lifting and Moving ..............................................................................................A-4

Tilting ..................................................................................................................A-4

Environmental Rating..........................................................................................A-4

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

Input Connections.....................................................................................................A-5

Input Reconnect Procedure ......................................................................................A-6

Output Connections..................................................................................................A-6

Connections for TIG Welding .............................................................................A-6

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

Work Cable Connection ..............................................................................A-7

Shielding Gas Connection...........................................................................A-7

Remote Control Connection........................................................................A-7

Connections for Stick Welding..................................................................................A-7

Stick Electrode Cable and Work Cable Connection ..........................................A-7

PRECISION TIG 185

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A-2

INSTALLATION

A-2

TECHNICAL SPECIFICATIONS - PRECISION TIG 185 (K2345-1AND K2347-1,-2)

Volts at Rated Amperes

15.2 V AC/DC

14.1 V AC/DC

13.8 V AC/DC

27.4 V AC/DC

23.6 V AC/DC

Type of Output

CC (Constant Current)

AC/DC

Amps

185AAC/DC

90AAC/DC (BAL)

70AAC (AUTO-BAL)

185AAC/DC125

90AAC/DC

Maximum Open

Circuit Voltage

(STICK AND TIG)

AC OCV: 75
DC OCV: 59

Input Current at Rated Output

35A / 32A Effective

and 70A / 64A Maximum

Duty Cycle

GTAW 15% Duty Cycle

100% Duty Cycle

SMAW 15% Duty Cycle

100% Duty Cycle

Output Current

Range

7-185 Amps (AC)
5-185 Amps (DC)

Standard Voltage

208/230/1/60

INPUT - SINGLE PHASE ONLY

OUTPUT RANGE

RATED OUTPUT

Chart gives max. rated Output Amps @% Duty Cycle (Based on a 10 minute cycle)
(Example; 110A@60% for AC/DC Stick and Balance TIG)

Using sta ndard #8-3 input cable for protected

(1)

input supply

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

50 70 90 110 130 150 170 190

208/230v Model: AC/DC Stick & DC TIG

(AC TIG with #6-3 input cable)
460/575v Model: AC/DC Stick & AC/DC TIG
380/415v Model: AC/DC Stick &
DC/AC Auto-Bal.TIG

208/230v Model: AC TIG using 230v input
380/415v Model: AC TIG (Max. Penetration)

208/230v Model: AC TIG using 208v input

OUTPUT AMPS

OUTPUT % DUTY CYCLE

(1)

Wiring and protection based on the 2002 U.S. National Electric Code:
Use a Super Lag type fuse or circuit breaker with a delay in tripping action.
Models with NEMA 6-50P plug may be used with a 50 amp protected 6-50R receptacle, or
with a maximum 70 amp protected 6-50R receptacle if dedicated for the welder.

PRECISION TIG 185

INSTALLATION

A-3 A-3

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TECHNICAL SPECIFICATIONS - CANADIAN (K2345-2), INTERNATIONAL K2346-1)

MODEL HEIGHT WIDTH DEPTH WEIGHT

PHYSICAL DIMENSIONS

(2)

W

eld Voltage (NEMA)

27.4 V

23.6 V

15.2 V

14.1 V

Output T

ype

CC (Constant Current)

AC or DC

Weld Current

185 A AC/DC

90 A AC/DC

185 A AC/DC

90 A AC/DC (Auto-Bal.)

Weld Current

7-185 A (AC)

5-185 A (DC).

Process Duty Cycle*.

SMAW

15%

100%

GTAW

15%

100%

Max. OCV.

74 V (AC)

59 V (DC)

OUTPUT RANGE

RATED OUTPUT

Machine Only

(K2345-1,-2)

(K2346-1)

Ready-Pak

(K2347-1)

Ready-PakW/Cart

(K2347-2)

20.71 in.
526 mm

20.71 in.
526 mm

31.24 in.
794 mm

14.48 in.
368 mm

14.48 in.
368 mm

19.81 in.
503 mm

25.62 in.
751 mm

25.62 in.
651 mm

38.01 in.
966 mm

Approx. 192 lbs.

87.1 kgs

Approx. 212lbs..

96.2 kgs.

Approx. 258lbs.

117.0 kgs.

(2)

Dimensions are without Lift Eyebolt and Torch Holder

Power Factor

0.62 Min.

Idle Current

1.3 A/1.0 A Max.

Current

16 A/13 A Effective

32 A/26 A Max.

Voltage/Phase/Freq.

460/575/1/60

K2345-2 INPUT (at Rated Output)

K2346-1 INPUT (at Rated Output)

Power Factor

0.62 Min.

Idle Current

1.3 A/1.0 A Max.

Current

19 A/18 A Effective

39 A/37 A Max.

Voltage/Phase/Freq.

380/400-415/1/50/60

* Based on a 10 minute cycle.

N80

PRECISION TIG 185

INSTALLATION

A-4 A-4

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SAFETY PRECAUTIONS

SELECT SUITABLE LOCATION

Place the welder where clean cooling air can freely cir­culate in and out through the rear louvers. 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 nuisance shut-downs.

GRINDING

Do not direct grinding particles towards the welder. An
abundance of conductive material can cause mainte­nance problems.

STACKING

Square Wave TIG 185 cannot be stacked.

LIFTING AND MOVING

The Precision TIG 185 models are provided with an
Eyebolt used for lifting the unit with a hoist. To install;
remove the plug button from the case top and screw
the Eyebolt securely into the threaded bracket
beneath the case top per the below instructions and
warnings provided on the case top decal. Save the
removed plug button (LE part No.T10397-2) to cover
the hole when the lift Eyebolt is removed.

An undercarriage, provided on the Ready-Pak w/Cart
model, is also available to easily move the the unit.
Refer to the Accessories section of this manual.

Do not attempt to lift the power source with an
undercarriage attached.

The undercarriage is designed for hand moving only;
mechanized movement can lead to personal injury
and/or damage to the Precision TIG 185.

TILTING

Each machine must be placed on a secure, level sur­face, either directly or on a recommended undercar­riage. The machine may topple over if this procedure is
not followed.

ENVIRONMENTAL RATING

The PRECISION TIG 185 power source carries an
IP21 environmental rating. It may be used in normal
industrial and commercial environments. Avoid using it
in environments which have falling water such as rain.

Read and follow “Electric Shock Warnings” in the
Safety section if welding must be performed under
electrically hazardous conditions such as welding in
wet areas or on or in the workpiece.

MACHINE GROUNDING AND HIGH FRE­QUENCY INTERFERENCE PROTECTION

This welder must be grounded! See your local and
national electrical codes for proper grounding
methods.

ELECTRIC SHOCK can kill.

• Only qualified personnel should

perform this installation.

•Turn the input power OFF at the
disconnect switch or fuse box
before working on this equipment.

• Do not touch electrically hot
parts.

• Always connect the SQUARE WAVE TIG 175 PRO
to a power supply grounded per the National
Electrical Code and any local codes.

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

WARNING

Read entire installation section before starting
installation.

• Use only Lincoln provided
T4550-5 1/2-13 x 1.00 eyebolt.

• Fully engage threads and
torque eyebolt to 38 ft. lbs.

• Re-torque eyebolt to 38 ft. lbs.
before each lift.

• Lift only with equipment of
adequate lifting capacity.

FALLING • Never lift welder with gas

EQUIPMENT cylinder attached.

cause injury. • Never lift welder above per-

sonnel.

• Lift only with equipment of adequate lifting

• Be sure machine is stable when lifting.

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

WARNING

PRECISION TIG 185

INSTALLATION

A-5 A-5

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The high frequency generator, being similar to a radio
transmitter, may cause radio, TV and electronic equip­ment interference problems. These problems may be
the result of radiated interference. Proper grounding
methods can reduce or eliminate radiated interference.

Radiated interference can develop in the following four
ways:

1. Direct interference radiated from the welder.

2. Direct interference radiated from the welding leads.

3. Direct interference radiated from feedback into the
power lines.

4. Interference from re-radiation of “pickup” by
ungrounded metallic objects.

Keeping these contributing factors in mind, installing
equipment per the following instructions should mini­mize problems.

1. Keep the welder power supply lines as short as pos­sible and enclose as much of them as possible in
rigid metallic conduit or equivalent shielding for a
distance of 50 feet (15.2m). There should be good
electrical contact between this conduit and the
welder case ground. Both ends of the conduit should
be connected to a driven ground and the entire
length should be continuous.

2. Keep the work and electrode leads as short as pos­sible and as close together as possible. Lengths
should not exceed 25 ft (7.6m). Tape the leads
together when practical.

3. Be sure the torch and work cable rubber coverings
are free of cuts and cracks that allow high frequen­cy leakage.

4. Keep the torch in good repair and all connections
tight to reduce high frequency leakage.

5. The work piece must be connected to an earth
ground close to the work clamp, using one of the fol­lowing methods:

a) A metal underground water pipe in direct contact

with the earth for ten feet or more.

b) A 3/4” (19mm) galvanized pipe or a 5/8”

(16mm)solid galvanized iron, steel or copper rod dri­ven at least eight feet into the ground.

The ground should be securely made and the ground­ing 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 along pipe
system can result in re-radiation, effectively making
these members radiating antennas.

6. Keep cover and all screws securely in place.

7. Electrical conductors within 50 ft (15.2m) of the
welder should be enclosed in grounded rigid metal­lic conduit or equivalent shielding, wherever possi­ble. Flexible metallic conduit is generally not suit­able.

8. When the welder is enclosed in a metal building,the
metal building should be connected to several good
earth driven electrical grounds (as in 5 (b) above)
around the periphery of the building.

Failure to observe these recommended installation
procedures can cause radio or TV and electronic
equipment interference problems and result in unsatis­factory welding performance resulting from lost high
frequency power.

INPUT CONNECTIONS

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.

208/230 volt models have a NEMA 6-50P plug
attached to the #8-3 input power cord and a NEMA 6 ­50R receptacle is included with the Ready-Pak mod­els. Other voltage models have an input power cord
but no plug or receptacle.

Have a qualified electrician provide input power supply
to the receptacle or cord in accordance with all local
and national electrical codes. Use a single phase line
or one phase of a two or three phase line. Choose an
input and grounding wire size according to local or
national codes. Refer to the Technical Specifications
page at the beginning of this section. Fuse the input
circuit with the recommended super lag fuses or delay
type

1

circuit breakers. Using fuses or circuit breakers
smaller than recommended may result
in “nuisance” shut-offs from welder inrush currents
even if not welding at high currents.

1

Also called “inverse time” or “thermal/magnetic” circuit breakers;
circuit breakers which have a delay in tripping action that decreases
as the magnitude of the current increases.

PRECISION TIG 185

INSTALLATION

A-6 A-6

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INPUT RECONNECT PROCEDURE

On multiple input voltage welders, be sure the machine
is connected per the following instructions for the volt­age being supplied to the welder.

Failure to follow these instructions can cause immedi­ate failure of components within the welder and void
machine’s warranty.

----------------------------------------------------------------------­Multiple voltage models are shipped connected for the

highest voltage. To change this connection refer to the
following instructions.

ELECTRIC SHOCK can kill.

• Turn the input power OFF at the dis­connect switch or fuse box before
working on this equipment.

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

For the lowest rated voltage connection (Refer to figure A.1):

1. Remove the sheet metal left side cover.

2. Disconnect lead H3 from the power switch and insu­late with the insulation from the H2 lead.

3. Connect lead H2 to the power switch where H3 was
connected.

4. Tighten connections.

5. Replace sheet metal cover and all screws

For the highest rated voltage connection (Refer to figure A.1):

The machine is normally shipped connected for the
highest rated voltage, however verify the following:

1. Remove the sheet metal left side cover.

2. Disconnect lead H2 from the power switch and insu­late with the insulation from the H3 lead.

3. Connect lead H3 to the line switch where H2 was
connected.

4. Tighten connections.

5. Replace sheet metal cover and all screws.

CONNECTIONS FOR TIG (GTAW) WELDING

TIG TORCH CONNECTION

Refer to Included Equipment in the Operation Section
of this manual for TIG welding equipment which is
included with the PRECISION TIG 185.

CAUTION

WARNING

FIGURE A.1 Reconnect Leads

INPUT LEADS

L1 & L2

LEAD H1

(DO NOT
REMOVE)

FOR LOWEST RATED VOLTAGE
: H2 CONNECTED
FOR HIGHEST RATED VOLTAGE
: H3 CONNECTED

BACK VIEW OF LINE SWITCH

OUTPUT CONNECTIONS

FIGURE A.2 Location of Output Connections

ELECTRODE/GAS

OUTLET
RECEPTACLE
(TWIST-MATE)

WORK CABLE & CLAMP

PRECISION TIG 185

INSTALLATION

A-7 A-7

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APTA-17 Twist-Mate TIG welding torch with cable and
connector is supplied with the Ready-Pak Models and
available for other models (See Accessories Section).
Turn the Power Switch “OFF”. Connect the torch cable
Twist-Mate quick connect plug into the Electrode/Gas
Output Receptacle on the front of the welder and turn
it clockwise until it is tight. This is a Twist-Mate quick
connect terminal and also provides the gas connection
for the shielding gas to the torch.

To avoid receiving a high frequency shock, keep
the TIG torch and cables in good condition.

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

WORK CABLE CONNECTION

A work cable with attached work clamp is factory con­nected to the PRECISION TIG 185. To minimize high
frequency interference, refer to Machine Grounding

and High Frequency Interference Protection

section of this manual for the proper procedure on
grounding the work clamp and work piece.

SHIELDING GAS CONNECTION

An adjustable gas pressure regulator with flow gage
and hose is supplied with the PRECISION TIG 185
Ready-Pak Models and available separately for other
models (See Accessories Section). Obtain the neces­sary inert shielding gas (usually argon). Connect the
cylinder of gas with the pressure regulator and flow
gage. Install the gas hose between the regulator and
gas inlet (located on the rear of the welder). The gas
inlet has a 5/16-18 right hand female thread;
CGA#032.

The available Under-Storage Cart features a low plat­form that simplifies loading and unloading of gas cylin­ders.

CYLINDER could explode
if damaged.

• Keep cylinder upright and chained
to a support.

• Keep cylinder away from areas
where it could be damaged.

• Never allow the torch to touch the cylinder.

• Keep cylinder away from live electrical circuits.

• Maximum inlet pressure 150 psi.

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

A cylinder is loaded by leaning it slightly sideways and
rocking it up on the platform, being careful not to allow
the Under-Storage Cart to roll. Secure the cylinder in
place with the provided chain. Unload by following
these steps in reverse.

REMOTE CONTROL CONNECTION

A remote control receptacle is provided on the case
front of the welder for connecting a remote control to to
the machine. A Foot Amptrol™, foot activated remote
control, is included with the PRECISION TIG 185
Ready-Pak models and available separately for other
models. Refer to the Optional Accessories section of
this manual for other available remote controls.

CONNECTIONS FOR STICK (SMAW)
WELDING

STICK ELECTRODE CABLE AND WORK
CABLE CONNECTION

Refer to Field Installed Options in Accessories Section
of this manual for STICK welding equipment which is
available for use with the PRECISION TIG 185. An
electrode holder with Twist-Mate cable and Twist-Mate
connector are available separately for use with the
PRECISION TIG 185. (See Accessories Section).
Turn the Power Switch “OFF”. Connect the Twist-Mate
quick connect plug into the Electrode/Gas Output
Receptacle and turn it clockwise until it is tight. The
work cable and work clamp are factory connected.

WARNING

WARNING

PRECISION TIG 185

NOTES

A-8 A-8

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PRECISION TIG 185

Section B-1 Section B-1

TABLE OF CONTENTS

- OPERATION SECTION -

Operation ................................................................................................................Section B

Safety Precautions .......................................................................................................B-2

Graphic Symbols..........................................................................................................B-2

Product Description......................................................................................................B-3

Recommended Processes and Equipment..................................................................B-3

Welding Capability (duty cycle) ....................................................................................B-3

Controls and Settings...................................................................................................B-4

Control Functionality .............................................................................................B-4/B-5

Operating Steps ...........................................................................................................B-5

Welding in TIG Mode....................................................................................................B-5

Pulse TIG Control .........................................................................................................B-5

Remote Control Operation ...........................................................................................B-6

Benefits of the Precision TIG 185 Design ....................................................................B-6

Welding in Stick Mode .................................................................................................B-7

Recommended Electrode Amperage Ranges..............................................................B-7

PRECISION TIG 185

OPERATION

B-2 B-2

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ELECTRIC SHOCK
can kill.

• Do not touch electrically live parts
or electrode with skin or wet cloth­ing.

•

Insulate yourself from work and
ground.

• Always wear dry insulating gloves.

•

Read and follow “Electric Shock Warnings” in the
Safety section if welding must be performed under
electrically hazardous conditions such as welding in
wet areas or on or in the workpiece.

-------------------------------------------------------------------------------­FUMES AND GASES
can be dangerous.

• Keep your head out of fumes.

• Use ventilation or exhaust at the

arc, or both, to remove fumes and
gases from breathing zone and
general area.

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

WELDING SPARKS can cause fire or
explosion

• Keep flammable material away.

• Do not weld on containers that
have held combustibles.

-----------------------------------------------------------------------­ARC RAYS can burn.

•Wear eye, ear and body

protection.

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

SAFETY PRECAUTIONS

Read and understand this entire section before operat­ing the machine.

Observe additional Safety Guidelines detailed in
the beginning of this manual.

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

WARNING

INPUT POWER

POSITIVE OUTPUT

NEGATIVE OUTPUT

DIRECT CURRENT

PROTECTIVE
GROUND

WARNING OR
CAUTION

DO NOT SWITCH
WHILE WELDING

GRAPHIC SYMBOLS THAT APPEAR ON
THIS MACHINE OR IN THIS MANUAL

PRECISION TIG 185

OPERATION

B-3 B-3

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PRODUCT DESCRIPTION

The Precision TIG 185 is a member of our field
acclaimed Precision TIG family of industrial arc weld ­ing power sources. Premium features include:

1. Precise constant current output.

2. Full range square wave AC/DC TIG (GTAW) weld--

ing.

3. Enhanced version of the patented Micro-

Start™Technology for its lower Minimum(5 amps) to
higher Maximum (185 amps) output control range.

4. Built-in high frequency stabilization for DC TIG start-

ing and continuous AC TIG welding.

5. AC/DC Stick (SMAW capability.) A new undercar-

riage (with gas bottle rack) is available for field
installation, or is included with an available Ready­Pak TIG Welding Package. The Precision TIG
patented convenient built-in storage provisions for
welding components and cable management.

The Precision TIG 185 also provides advanced fea­tures such as:

• Digital Meter

• Presettable control, adjustable Auto Balance™

• Fan As Needed (F.A.N.)

• Timers for fixed Preflow and variable Postflow shield-

ing gas.

• Built-in, easy to set single knob Pulse TIG control with

a "blinking" light to indicate the pulse frequency set­ting.

• Auto-Sense remote control selection.

• Tool-less Twist-Mate electrode cable connection.

• Built-in work clamp cable permanently attached.

Four models are available for 60Hz. with Domestic and
Canadian input voltages, as well as an International
model with 50/60Hz voltages.

RECOMMENDED PROCESSES AND
EQUIPMENT

RECOMMENDED PROCESSES

The Precision TIG 185 is recommended for the TIG
(GTAW) and Stick (SMAW) welding processes within
its output capacity range of 5 amps DC,or 7 amps AC,
to 185 amps AC/DC. It is compatible with most
Magnum TIG accessories, as well as many industry
standard items, such as TIG torches (adapted for
Twist-Mate), hoses, and water coolers.

PROCESS LIMITATIONS

The 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

(See Installed Options in Accessories Section for
more details)

The Precision TIG 185 will be available as a basic
Machine (Only) and in two Factory-Configured Welding
Packages:

1. Machine(Only) (K2345-1)

2. Ready-Pak (K2347-1)

3. Ready-Pak w/Cart (K2347-2)
Basic module will also be available as with Domestic,

Canadian and International input voltages for user con­figuration, with optional accessories.

Select Machine 208/230/1/60 Machine with 6 NEMA 6-50P

Plug Cable and Receptacle (K2345-1)

460/575/1/60 Machine only with cable (K2345-2)

380/400/415/1/50/60 Machine only

with cable (K2346-1)
Torch Starter Kit Air Cooled System: Water Cooled System:
(Select one) TIG-Mate TIG-Mate 20

Torch Starter Kit* Torch Starter Kit*

Water Cooler Not Applicable 115V 50/60Hz

Cool-Arc 40*
Under-Storage K2348-(*)
Cart (Optional )
Optional Remote Arc Start Switch*
Trigger Device Foot Amptrol*
(Select one) Start Pedal Foot Amptrol*

Hand Amptrol*

*For “Part Numbers” or “K Numbers” see Accessories Section.

EQUIPMENT LIMITATIONS

The Precision TIG machines are protected from over
loads beyond the output ratings and duty cycles, per
the Specifications in the Installation Section, with
Thermostat protection of the output power coils and
rectifiers.

The PRECISION TIG 185 machine uses Twist-Mate
output terminals, therefore stud connection adapters
(such as LECO. S19257-series) cannot be used for
torch connection.

If a Precision Tig 185 is powered from an engine gen­erator which doesn’t have sufficient capacity, the AC
Balance control and the Output control will not provide
full range of control.

WELDING CAPABILITY(Duty Cycle)

The PRECISION TIG 185 is rated at 185 amps, 27
volts, at 15% duty cycle on a ten minute basis. It is
capable of higher duty cycles at lower output currents.
See rated output graph, on specification sheet located
in the Installation Section. If the duty cycle is exceed­ed, a thermal protector will shut off the output until the
machine cools.

PRECISION TIG 185

OPERATION

B-4 B-4

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CONTROL FUNCTIONALITY

1. POWER SWITCH – Input line switch turns input

power ON or OFF, as indicated by the on or off sta­tus of the front panel digital display (See Item 6).

2. POLARITY SWITCH – The rotary power switch has
3-positions for DC+, AC and DC- selections for the
electrode output stud welding polarity.

• Do not switch the polarity switch
while welding or damage may result
to the machine.

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

3. MODE SWITCH – The push button switch allows
selection of the two machine welding modes as indi­cated by colored mode lights:

• STICK mode – Top position Red light.

• TIG mode – Bottom position Green light.

4. AC BALANCE CONTROL – The AC Balance
Control permits adjustment of the AC TIG wave bal­ance adjustment from Max. Penetration (80% nega­tive wave) at full CW rotation setting, to Max.
Cleaning (60% positive wave) at CCW rotation, and
includes:

• Auto Balance position indicated by the Green panel
light turning on.

This setting position feature automatically provides the
proper amount of cleaning and penetration for normal
AC TIG welding.

5. MAXIMUM OUTPUT CONTROL – Presets the out-

put welding current over the rated output range of
the machine:

• With a Remote Current Control (Amptrol) connect­ed to the Remote Receptacle (See item 10), this
knob sets the Maximum output current level set
table with the remote Amptrol.

• For Pulse TIG (See Item 8) this knob sets the Peak
Pulse level, with the Remote Amptrol (if used).

6. DIGITAL METER – A 3 digit LED meter is used to
display the preset output current level before weld­ing, and actual output level while welding:

• A lit display indicates input power is turned on.
(See Item 1.)

7. POST FLOW TIME – Sets the TIG mode shielding
gas post flow time over the range of about 1 to 30
seconds after the arc is shut off.

Note: Gas preflow time is fixed at 0.5 second only in
TIG mode, but no preflow time will occur if the arc is
restarted during Post Flow time, since shielding gas
would not have stopped flowing.

CONTROLS AND SETTINGS

All operator controls and adjustments are located on the front of the PRECISION TIG 185. Refer to Figure B.1
and corresponding explanations.

FIGURE B.1 - CONTROL PANEL

1. POWER SWITCH

2. POLARITY SWITCH

3. MODE SWITCH

4. AC BALANCE CONTROL

5. MAXIMUM

OUTPUT CONTROL (AMPS)

6. DIGITAL METERS

7. POST FLOW TIME

8. PULSE TIG CONTROL

9. THERMAL SHUTDOWN LIGHT

10. REMOTE RECEPTACLE

11. ELECTRODE/GAS OUTPUT
RECEPTACLE

12. WORK CABLE

13. REMOVABLE LIFT EYEBOLT

5

13

2

6

3

4

1

7

9

10

11

12

8

CAUTION

PRECISION TIG 185

OPERATION

B-5 B-5

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8. PULSE TIG CONTROL – The Pulse TIG feature
built into the Precision TIG 185 is simplified to be a
single knob control which sets the Pulse Frequency
over the peak pulses/sec. range of about 0.1 to 20
pulses per second:

• Full CCW (min.) setting of the control knob shuts
off Pulse TIG (0.0 pps).

• Peak Pulse level is set by the Max. Output Control
and the Remote Amptrol (if used).

• Background Current level is typically optimized at
a fixed 50% of Peak Pulse level setting.

• Peak Pulse % On-time is typically optimized at a
fixed50%.

A Green light "blinks" with each Peak Pulse to indi­cate the Pulse TIG Control setting before and during
welding.

9. OVER TEMPERATURE LIGHT - If the welder
overheats due to blocked air flow, high ambient air
temperature, or exceeded duty cycle, an internal
thermostat will open disabling the welding output
and this yellow light will illuminate. The cooling fans
will continue to run to cool the unit during this time.
The light will go out when the unit cools and the
thermostat resets. Once the light goes out, the
machine will again become available to weld.

10. REMOTE RECEPTACLE – Provides for connec-

tion of remote control and/or arc start switch only in
TIG Mode: ( There is no remote output control
capability when stick welding.

• Plugging a remote current control (Amptrol) into
this receptacle automatically switches the output
control from the panel Max Output Control (See
Item 5) to the remote control.

• The connected remote control will then control the
output current between the Min. range of the
machine and the setting of the panel Max Output
Control.

• Switching Mode Switch (See Item 3) to Stick will
automatically disable the connected remote con­trol and switch the output control back to the Max
Output panel control.

11. ELECTRODE/GAS OUTPUT RECEPTACLE -

This quick connect Twist-Mate receptacle provides
electrical connection to the electrode holder and
cable for Stick welding and a combined electrical
and gas connection for the TIG torch when TIG
welding.

12. WORK CABLE - This work cable is factory con­nected to the welder and is connected to the work
piece to complete the welding circuit. Refer to

Machine Grounding and High Frequency
Interference Protection in the Installation section

of this manual for the proper procedure on ground­ing the work clamp and work piece to minimize
high frequency interference.

OPERATING STEPS

WELDING IN TIG MODE

1. Connect the TIG torch and cable Twist-Mate quick
connect plug to the Electrode/Gas output recepta­cle. This receptacle also contains an integral gas
connection for the torch. Connect the work clamp to
the work piece.

2. Set the TIG/STICK switch to “TIG”.

3. Set the Polarity Switch to DC- for welding steel or
stainless steel; or to AC for welding aluminum.

4. Connect the Foot Amptrol to the Remote Control
Connector.

5. Turn on the cylinder gas valve and adjust the flow
regulator to obtain desired flow.

6. Turn the power switch to “ON”. NOTE: There will be
a 15 second gas flow when the power is turned on.

7. Preset the Output Control on the control panel to the
maximum desired amps, as read on the digital
meter.

8. Depress the Foot Amptrol to energize the torch and
establish an an arc with the work piece. The digital
meter reads the actual amps while welding.

NOTE: When the TIG/STICK switch is set to “TIG”,
depressing the remote control will start a 0.5 second
gas pre-flow before energizing the TIG torch. When the
remote control is released the TIG torch is de-ener­gized and gas flow will continue for the time set by the
Post Flow Time control. When the polarity switch is set
to DC, the TIG Arc Starter will turn on and off automat­ically to start and stabilize the arc. In AC the TIG Arc
Starter will turn on with the output and remain on con­tinuously until the remote control is released.

PULSE TIG CONTROL

Use this knob to set the frequency or the number of
pulses per second(pps), from 0.1pps to 20pps.

• This setting adjusts heat output and bead shape for

travel speed. Thinner plate that is welded with faster
travel speed will require higher frequency than thick­er plate with slower travel speed. 2-3pps is a typical
starting point.

PRECISION TIG 185

OPERATION

B-6 B-6

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REMOTE CONTROL OPERATION

A Foot Amptrol ™is included with the PRECISION TIG
185 Ready-Pak models and availiable for other models
(See Accessories Section) for remote current control
while TIG welding. An optional Hand Amptrol may also
be used. An optional Arc Start Switch may be used to
start and stop the welding if no remote control of the
current is desired. Refer to the Accessories Section of
this manual.

Both the Hand and Foot Amptrol work in a similar man­ner. For simplicity, the following explanation will refer
only to “Amptrols”, meaning both Foot and Hand mod­els. The term “minimum” refers to a foot pedal in the
“up” position, as it would be with no foot pressure, or a
Hand Amptrol in the relaxed position, with no thumb
pressure.

“Maximum” refers to a fully depressed Foot Amptrol,or
a fully extended Hand Amptrol.

When the welder is in TIG modes activating the
Amptrol energizes the electrode terminal and varies
the output welding current from its minimum value of 5
Amp (DC) or 7 Amp (AC), to the maximum value set by
the Current Control on the control panel. This helps
eliminate accidental high current damage to the work
piece and/or tungsten, and provides a fine control of
the current. When the welder is in the stick mode a
remote control has no effect and is not used.

It is important to note that, in some cases, the tungsten
will not start an arc at the minimum current because
the tungsten may be too large or cold. To start an arc
reliably, it is important to depress the Amptrol far
enough so that the machine output current is near the
tungsten operating range. For example, a 3/32” tung­sten may be used on DC- to weld over the full range of
the machine.

To start the arc, the operator may have to turn the cur­rent control up and depress the Amptrol approximately
1/4 of the way down. Depressing the Amptrol to its min­imum position may not start the arc. Also if the current
control is set too low, the arc may not start. In most
cases, a large or cold tungsten will not readily establish
an arc at low currents. This is normal. In Direct Current
mode the PRECISION TIG 185 will start a 3/32”, 2%
thoriated tungsten electrode at 15 amperes provided
the electrode tip is properly grounded and not contam­inated.

BENEFITS OF THE PRECISION TIG 185 DESIGN

In AC TIG welding of aluminum, the positive portion of
the AC wave provides cleaning (removal of aluminum
oxide) of the work piece. This is desirable on materials
with a heavy oxide coating. However the positive por­tion may also cause the electrode to overheat at high
currents causing “tungsten spitting”. The negative por­tion of the AC wave offers no cleaning action but con­centrates more heat on the work.

The AC waveform of the PRECISION TIG 185 opti­mizes cleaning and heating of the work. The result is
the capability to weld through the complete range in AC
TIG or DC- TIG requiring only one electrode, a 3/32”
2% thoriated tungsten.

PRECISION TIG 185

OPERATION

B-7 B-7

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WELDING IN STICK MODE

1. Put the electrode holder and cable quick connect
plug into the electrode output receptacle. Turn clock­wise until tight. Connect the work clamp to the work
piece.

2. Set the TIG/STICK switch to “STICK”.

3. Set the Polarity Switch to the weld mode desired for
the type of electrode being used (most commonly
DC+).

4. Place the electrode in the electrode holder.

• In Stick Mode the output terminal
and electrode will be electrically hot
whenever the power switch is turned
on.

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

5. Turn the power switch to “ON”.

6. Adjust the Current Control to the desired amps.

7. Strike an arc and weld.
NOTE: When the TIG/STICK switch is set to “STICK”

the output is always on when the power switch is on. A
remote control has no effect on the welding current and
the gas flow and high frequency TIG arc starter are dis­abled.

RECOMMENDED ELECTRODE AMPERAGE RANGES - PRECISION TIG 185

The PRECISION TIG 185 is rated from 5-185 Amps.

SMAW Process

Welding Amp Range for Stick Electrode Size

ELECTRODE TYPE POLARITY 3/32" 1/8" 5/32"
Fleetweld 5P, Fleetweld 5P+ E6010 DC+ 40 - 70 75 - 130 90 - 175
Fleetweld 180 E6011 DC+ 40 - 80 55 - 110 105 - 135
Fleetweld 37 E6013 DC+ 70 - 95 100 - 135 145 - 180
Fleetweld 47 E7014 DC- 75 - 95 100 - 145 135 - 200
Excalibur E7018 DC+ 85 - 110 110 - 160 130 - 200
Blue Max Stainless DC+ 40 - 80 75 - 110 95 - 150
Red Baron Stainless DC+ 40 - 70 60 - 100 90 - 140

Mild steel procedures are based on recommended procedures listed in C2.10 8/94 and the maximum rating of the PRECISION TIG 185
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

Electrode Tip Preparation Sharpened Balled Gas Flow Rate

Electrode Type

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

EWTh-1, EWCe-2 EWTh-1, EWTh-2

EWTh-2, EWLa-1 EWP EWCe-2, EWLa-1 Stainless

Tungsten Size (in.) EWG EWG Aluminum Steel

.010 Up to 15 A. Up to 10 A. Up to 15 A. 3-8 (2-4) 3-8 (2-4)
.020 Up to 15 A. Up to 15 A. Up to 20 A. 5-10 (3-5) 5-10 (3-5)
.040 Up to 80 A. Up to 40 A. Up to 60 A. 5-10 (3-5) 5-10 (3-5)
1/16 Up to 150 A. Up to 100 A. Up to 130 A. 5-10 (3-5) 9-13 (4-6)
3/32 Up to MAX. A. Up to 160 A. Up to MAX. A. 13-17 (6-8) 11-15 (5-7)

1/8 X Up to MAX. A. X 15-23 (7-11) 11-15 (5-7)

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

Pure..................................EWP........green TRI-MIX OF ELEMENTS.............EWG.........gray

+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.

WARNING

PRECISION TIG 185

NOTES

B-8 B-8

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PRECISION TIG 185

Section C-1 Section C-1

TABLE OF CONTENTS

- ACCESSORIES SECTION -

Accessories ............................................................................................................Section C

Options / Accessories ...........................................................................................C-2/C-3

PRECISION TIG 185

ACCESSORIES

C-2 C-2

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FACTORY INSTALLED OPTIONS

The Precision TIG 185 will be available in two Factory­Configured Welding Packages:

1. Precision TIG 185 Ready-Pak (K2347-1)

• 208/230/1/60 Machine (K2345-1)

• 9 ft. (2.7m) Input Cable with NEMA 6-50P Plug*

• NEMA 6-50R Receptacle

• Integrated 10 ft.(3.1m)Work Lead w/Clamp*

• Gas Regulator with 10 ft.(3.1m). Hose

• PTA-17 12.5”(318mm) Ultra=Flex Torch with
3/32”(2.4mm)Electrode and Parts

• Foot Amptrol (K870)

• TIG Slide Rule ( WC332)*

• GTAW Book (JFLF-834)*

• Lift Eyebolt*

The Precision TIG 185 will also be available as Basic
models with Domestic input voltages for user-configu­ration with optional accessories: (See Table C.1)

2. Precision TIG 185 Ready-Pak w/Cart (K2347-2)

• 208/230/1/60 Machine (K2345-1)

• 9 ft.(2.7m) Input Cable with NEMA 6-50P Plug*

• NEMA 6-50R Receptacle

• Integrated 10 ft.(3.1m) Work Lead w/Clamp*

• Gas Regulator with 10 ft.(3.1m) Hose

• PTA-17 12.5 ft.(3.8m) One cable Superflex Torch with
3/32”(2.4mm) Electrode and Parts

• Foot Amptrol (K870)

• TIG Slide Rule (WC332)*

• GTAW Book (JFLF-834)*

• Lift Eyebolt*

• Under-Storage Cart (K2348-1)

* Included with K2345-1 Machine Only model.

Water Cooled System

K2267-1 TIG-Mate 20 Torch Starter Kit
Includes:

• 200A PTW-20 12.5 ft.(3.81m) Torch

• KP510 Parts Kit

• Regulator & Hose

• K1622-4 Twist Mate Torch Adapter

• Water Hose & Hose Coupler

• Work Cable & Clamp (Not required for
Precision TIG 185)

Not Applicable

Select Machine

Optional
Torch Starter Kit
(Select one)

Water Cooler
Optional Under-

Storage Cart
Optional Remote

Trigger Device
(Select one)

208/230/1/60 Machine with 9 ft.(2.7m) NEMA 6-50P Plug Cable and Receptacle (K2345-1)
460/575/1/60 Machine only with Cable (K2345-2)
380/400-415/1/50-60 Machine only with Cable (K2346-1)

Air Cooled System

K2266-1 TIG-Mate Torch Starter
Kit Includes:

• 150A PTA-17 12.5 ft.(3.81m) Torch.

• KP508 Parts Kit.

• Regulator & Hose.

• K1622-1 Twist Mate Torch Adapter.

• Work Cable & Clamp (Not required for Precision
TIG 185)

K1813-1 115V 50/60Hz Cool-Arc 40

TABLE C.1

K2348-1
K814 Arc Start Switch

K870 Foot Amptrol
K870-1 Start Pedal Foot Amptrol
K963-3 Hand Amptrol

PRECISION TIG 185

ACCESSORIES

C-3 C-3

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FIELD INSTALLED OPTIONS

The following Options/Accessories are available for the
Precision TIG 185:

• K2348-1 Under-Storage Cart
Includes a front magnetic latch storage drawer and
rear storage bin on a single bottle undercarriage.
(L12225 Installation Instructions included)

• K870 Foot Amptrol

Single pedal foot activation of arc start switch and
output control, with 25 ft.(7.6m) plug cable.

• K870-1 Start Pedal Foot Amptrol

Independent start pedal on control pedal provides
two-stage foot action to easily feel start switch clo­sure at minimum output level for enhanced arc start
and crater-fill control. Provided with adjustable, or
removable , heel stop and 25 ft.(7.6m) plug cable.

• K963-3 Hand Amptrol

Fastens to torch for convenient thumb activation of
arc start switch and output control, with 25 ft.(7.6m)
plug cable:

• K814 Arc Start Switch

Needed for TIG welding without an Amptrol. Includes
25 ft.(7.6m) plug cable, and attaches to torch for
convenient finger control.

• TIG-Mate Torch Starter Kits:

Includes Torch with Twist-Mate adapter and acces­sories listed below:

K2266-1 TIG-Mate Torch Starter Kit Includes:

• 150A PTA-17 12.5 ft.(3.8m) Torch

• KP508 Parts Kit

• Regulator & Hose

• K1622-1 Twist Mate Torch Adapter

• Work Cable & Clamp (Not required for Precision
TIG 185)

K2267-1 TIG-Mate 20 Torch Starter Kit Includes:

• 200A PTW-20 12.5 ft.(3.8m) Torch

• KP510 Parts Kit

• Regulator & Hose

• K1622-4 Twist Mate Torch Adapter

• Water Hose & Hose Coupler

• Work Cable & Clamp
(Not required for Precision TIG 185)

• Magnum “Pro-Torch™ TIG Torch” assemblies and
Accessories.

Requires Twist-Mate Adapter:

K1622-1 for PTA-9/-17
K1622-3 for PTA-26
K1622-4 for PTW water cooled torch

• Harris #3100211 Harris Argon Flow Regulator

(Includes 10 ft.(3.1m) hose.)

• K2374-1 Electrode Holder and Cable

200 amp Electrode Holder with 10 ft.(3.1m) cable
and Twist-Mate connector.

PRECISION TIG 185

NOTES

C-4 C-4

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PRECISION TIG 185

Section D-1 Section D-1

TABLE OF CONTENTS

- MAINTENANCE SECTION -

Maintenance ...........................................................................................................Section D

Safety Precautions ........................................................................................................D-2

Routine Maintenance.....................................................................................................D-2

Periodic Maintenance....................................................................................................D-2

Spark Gap Adjustment ..................................................................................................D-2

Fan Motor and Blade Replacement ..............................................................................D-2

Major Component Locations.........................................................................................D-3

PRECISION TIG 185

MAINTENANCE

D-2 D-2

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SAFETY PRECAUTIONS

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.

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

To avoid receiving a high frequency shock, keep
the TIG torch and cables in good condition.

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

ROUTINE AND PERIODIC MAINTENANCE

1. Disconnect power supply lines to machine before
performing periodic maintenance.

2. Periodically clean the inside of the machine with a
low pressure air system. Be sure to clean the fol­lowing components thoroughly.

• Main Transformer

• Electrode/Gas Output Receptacle

• Polarity Switch

• Rectifier Assembly

• Arc Starter/Spark Gap Assembly

• PC Boards

• Fan Blades

3. Inspect welder output and control cables for fraying,
cuts, and bare spots.

4. Keep TIG torch and cables in good condition.

5. Clean air louvers to ensure proper air flow and cool­ing.

6. The fan motor has sealed ball bearings which
require no maintenance.

7. SPARK GAP ADJUSTMENT
The spark gap is set at the factory to a gap of 0.020

See Figure D.1. This setting is adequate for most
applications. Where less high frequency is desired,
the setting can be reduced to 0.015 inches (0.4mm).

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 machine. This is particularly important when
working on the secondary circuit of the high volt­age transformer (T3) because the output voltage is
dangerously high.

----------------------------------------------------------------------­Refer to figure D.1. 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 the spark gap. Do not disturb the facto­ry setting.

To check the spark gap:

- Turn off input power as specified above.

- Remove the right side panel from the
machine, the spark gap box is located on the
lower right side.

- Check the spark gap with a feeler gauge.

If adjustment is needed:

- Adjust the gap by loosening the allen head
screw in one of the aluminum blocks, near
the front of the unit and tighten the screw in
the new position.

If the gap is correct:

- Replace the wraparound.

8. Inspect gas hose and inlet fitting for cracks or leaks.

9. Replace any unreadable labels or decals.

10. Verify that the machine and welding circuit is prop­erly grounded.

FIGURE D.1 SPARK GAP

FAN MOTOR OR FAN BLADE REPLACEMENT

When installing a new fan blade or fan motor be sure
to maintain proper shaft spacing per Figure D.2 below.

WARNING

WARNING

WARNING

.020 Spark Gap

FIGURE D.2

.30

PRECISION TIG 185

MAINTENANCE

D-3 D-3

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FIGURE D.2 — LOCATION OF MAINTENANCE COMPONENTS.

1

9

5

8

8

3

6

2

4

7

1. Case Front Assembly

2. Case Back Assembly

3. Arc Starter & Bypass Assembly

4. Center Assembly

5. Cover Assembly

6. Cart Base Assembly

7. Upper Cylinder Support Assembly

8. TIG Torch & Cable Assembly

9. Foot Amptrol Assembly (Pedal)

X

NOTES

D-4 D-4

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X

Section E-1 Section E-1

Theory of Operation ...............................................................................................Section E

General Description ......................................................................................................E-2

Input Power Circuit .......................................................................................................E-2

Output Rectification and Feedback Control.................................................................E-3

High Voltage/High Frequency Circuit ...........................................................................E-4

DC Welding Output.......................................................................................................E-5

AC Welding Output.......................................................................................................E-6

SCR Operation..............................................................................................................E-7

Protective Circuits.........................................................................................................E-8

Thermal Protection .......................................................................................................E-8

Overload Protection......................................................................................................E-8

TABLE OF CONTENTS

- THEORY OF OPERATION SECTION -

FIGURE E.1 – PRECISION TIG 185 BLOCK LOGIC DIAGRAM

INPUT
POWER
SWITCH

MAIN

TRANSFORMER

POLARITY

SWITCH

SCR

BRIDGE

X1

X2

AC

AC

DC+

DC-

CONTROL

BOARD

18VAC

18VAC

115VAC

FAN

REMOTE

RECEPTACLE

H1

H2
H3

SHUNT

115VAC

HIGH VOLTAGE
TRANSFORMER

CIRCUIT

BY-PASS

BOARD

HI-FREQUENCY
TRANSFORMER

C
H
O
K
E

WORK

ELECTRODE

THERMAL

LIGHT

GAS

VALVE

THERMO-

STATS

OUTPUT
CONTROL

MODE

SWITCH

POWER

"ON"

DIGITAL
DISPLAY

F
E
E

D

B

A

C

K

AUTO
BALANCE
LED

TIG
LED

STICK
LED

PULSE
FREQ.
LED

BYPASS
ASBLY

AC
BALANCE
CONTROL

PULSE
CONTROL

POSTFLOW
CONTROL

PRECISION TIG 185

THEORY OF OPERATION

E-2 E-2

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INPUT POWER CIRCUIT

The desired single-phase input power is connected to
the TIG 185 through an input power switch located in
the front panel of the machine. The machine can be
configured for either 230VAC or 208VAC input voltage
by connecting the appropriate lead (H2 or H3) to the
input power switch. When the input power switch is
turned “ON” the input voltage is applied directly to the
primary of the main transformer.

The main transformer changes the high voltage, low
current input power to a low voltage, high current out­put which is available at the main secondary winding
(X1 and X2). In addition three auxiliary windings are

incorporated in the main transformer. The 115VAC
winding supplies power to the fan motor and also,
through the control board, powers the gas solenoid
valve and the high voltage transformer. The 18VAC
winding provides power to the trigger circuitry. The
other 18VAC winding is rectified and regulated to a
15VDC supply which operates the circuitry on the con­trol board.

FIGURE E.2 Main Transformer and Input Power

INPUT
POWER
SWITCH

MAIN

TRANSFORMER

POLARITY

SWITCH

SCR

BRIDGE

X1

X2

AC

AC

DC+

DC-

CONTROL

BOARD

18VAC

18VAC

115VAC

FAN

REMOTE

RECEPTACLE

H1

H2
H3

SHUNT

115VAC

HIGH VOLTAGE

TRANSFORMER

CIRCUIT

BY-PASS

BOARD

HI-FREQUENCY
TRANSFORMER

C
H
O
K
E

WORK

ELECTRODE

THERMAL

LIGHT

GAS

VALVE

THERMO-

STATS

OUTPUT
CONTROL

MODE

SWITCH

POWER

"ON"

DIGITAL
DISPLAY

F
E
E
D
B
A
C
K

AUTO
BALANCE
LED

TIG
LED

STICK
LED

PULSE
FREQ.
LED

BYPASS
ASBLY

AC
BALANCE
CONTROL

PULSE
CONTROL

POSTFLOW
CONTROL

NOTE: Unshaded areas of block logic diagrams are the subject of discussion.

GENERAL DESCRIPTION

The PRECISION TIG 185 is a member of our field
acclaimed Precision TIG family of industrial arc weld­ing power sources. Premium features include:

1. Precise constant current output.

2. Full range square wave AC/DC TIG (GTAW) weld­ing.

3. Enhanced version of the patented MicroStart

TM
Technology for its lower Minimum (5amps) to high­er Maximum (185 amps) output control range.

4. Built-in high frequency stabilization for DC TIG
starting and continuous AC TIG welding.

5. AC/DC Stick (SMAW capability.)

PRECISION TIG 185

THEORY OF OPERATION

E-3 E-3

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OUTPUT RECTIFICATION AND
FEEDBACK CONTROL

The AC output from the main transformer secondary is
rectified and controlled through the SCR bridge.
Output current is sensed at the shunt as a low voltage
signal and fed back to the control board. The control
board compares the commands of the mode switch,
output control, AC balance control, pulse control, post­flow control, or remote control with the feedback infor­mation. The appropriate SCR gate firing signals are
created by the control board and sent to the SCR
bridge. The control board controls the firing of the
SCRs, which control the output of the machine. See
SCR Operation. The control board monitors the ther­mostats, and also controls the gas solenoid valve, ther­mal light, auto balance LED, pulse frequency LED, TIG
LED, stick LED, and the digital display.

FIGURE E.3 Control Board and Output Feedback Control.

INPUT
POWER
SWITCH

MAIN

TRANSFORMER

POLARITY

SWITCH

SCR

BRIDGE

X1

X2

AC

AC

DC+

DC-

CONTROL

BOARD

18VAC

18VAC

115VAC

FAN

REMOTE

RECEPTACLE

H1

H2
H3

SHUNT

115VAC

HIGH VOLTAGE
TRANSFORMER

CIRCUIT

BY-PASS

BOARD

HI-FREQUENCY
TRANSFORMER

C
H
O
K
E

WORK

ELECTRODE

THERMAL

LIGHT

GAS

VALVE

THERMO-

STATS

OUTPUT
CONTROL

MODE

SWITCH

POWER

"ON"

DIGITAL
DISPLAY

F
E
E
D
B
A
C
K

AUTO
BALANCE
LED

TIG
LED

STICK
LED

PULSE
FREQ.
LED

BYPASS
ASBLY

AC
BALANCE
CONTROL

PULSE
CONTROL

POSTFLOW
CONTROL

NOTE: Unshaded areas of block logic diagrams are the subject of discussion.

PRECISION TIG 185

THEORY OF OPERATION

E-4 E-4

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HIGH VOLTAGE / HIGH
FREQUENCY CIRCUIT

The control board passes the 115VAC voltage to the
primary of the high voltage transformer. The sec­ondary of the high voltage transformer is coupled to a
spark gap generator and also to the high frequency
transformer. The high frequency transformer transfers
the high frequency “spark” to the electrode terminal
which is coupled to the TIG torch.

FIGURE E.4 High Voltage/High Frequency Circuit.

INPUT
POWER
SWITCH

MAIN

TRANSFORMER

POLARITY

SWITCH

SCR

BRIDGE

X1

X2

AC

AC

DC+

DC-

CONTROL

BOARD

18VAC

18VAC

115VAC

FAN

REMOTE

RECEPTACLE

H1

H2
H3

SHUNT

115VAC

HIGH VOLTAGE
TRANSFORMER

CIRCUIT

BY-PASS

BOARD

HI-FREQUENCY
TRANSFORMER

C
H
O
K
E

THERMAL

LIGHT

GAS

VALVE

THERMO-

STATS

OUTPUT
CONTROL

MODE

SWITCH

POWER

"ON"

DIGITAL
DISPLAY

F
E
E
D
B
A
C
K

BYPASS
ASBLY

NOTE: Unshaded areas of block logic diagrams are the subject of discussion.

PRECISION TIG 185

THEORY OF OPERATION

E-5 E-5

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DC WELDING OUTPUT

When the polarity switch is placed in either DC position, the AC voltage from the main transformer secondary is

applied to the SCR bridge. The SCR bridge and choke circuits are connected in a conventional full wave bridge

and filter configuration, resulting in a controlled DC output. Since the choke is in series with the negative leg of

the bridge and also in series with the welding load, a filtered DC is applied to the machine output terminals.

FIGURE E.5 DC Welding Current Generation.

CHOKE

WORK

ELECTRODE

PRIMARY

1Ø

G

G

G

G

DC

PRECISION TIG 185

THEORY OF OPERATION

E-6 E-6

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AC WELDING OUTPUT

Rotating the polarity switch to the AC position changes the welding power circuit. One lead (X1) of the main

transformer secondary is connected to the machine output work terminal. The other secondary lead (X2) is

connected to one of the AC connections on the SCR bridge. The electrode terminal is connected to the other

AC side of the bridge. The choke is now electrically across the negative and positive SCR bridge connections.

With the ability of the choke to store energy and the SCRs to turn on at the appropriate times, an AC square

wave is developed and applied to the output terminals.

FIGURE E.6 AC Square Wave Welding Current Generation.

CHOKE

WORK

ELECTRODE

PRIMARY

1Ø

G

G

G

G

DC

AC

PRECISION TIG 185

THEORY OF OPERATION

E-7 E-7

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SCR OPERATION

A silicon controlled rectifier (SCR) is a three terminal
device used to control rather large currents to a load.
An SCR acts very much like a switch. When a gate
signal is applied to the SCR it is turned ON and there
is current flow from anode to cathode. In the ON state
the SCR acts like a closed switch. When the SCR is
turned OFF there is no current flow from anode to
cathode thus the device acts like an open switch. As
the name suggests, the SCR is a rectifier, so it pass­es current only during positive half cycles of the AC
supply. The positive half cycle is the portion of the
sine wave in which the anode of the SCR is more
positive than the cathode.

When an AC supply voltage is applied to the SCR, the
device spends a certain portion of the AC cycle time in
the on state and the remainder of the time in the off
state. The amount of time spent in the ON state is con­trolled by the Gate.

An SCR is fired by a short burst of current into the gate.
This gate pulse must be more positive than the cath­ode voltage. Since there is a standard PN junction

between gate and cathode, the voltage between these
terminals must be slightly greater than 0.6V. Once the
SCR has fired it is not necessary to continue the flow
of gate current. As long as current continues to flow
from anode to cathode the SCR will remain on. When
the anode to cathode current drops below a minimum
value, called holding current, the SCR will shut off.
This normally occurs as the AC supply voltage passes
through zero into the negative portion of the sine wave.
If the SCR is turned on early in the positive half cycle,
the conduction time is longer resulting in greater SCR
output. If the gate firing occurs later in the cycle the
conduction time is less resulting in lower SCR output.

FIGURE E.7 SCR Operation

CATHODE

ANODE

GATE

GATE

INPUT

OUTPUT

NOTE: AS THE GATE
PULSE IS APPLIED
LATER IN THE CYCLE
THE SCR OUTPUT
IS DECREASED.

PRECISION TIG 185

THEORY OF OPERATION

E-8 E-8

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PROTECTIVE CIRCUITS

Protective circuits are designed into the PRECISION
TIG 185 to sense trouble and shut down the machine
before the trouble damages the internal machine com­ponents. Both thermal protection and current overload
are included. Fan as needed (F.A.N.) Fan runs for 5
seconds at power-up and stops at idle 8 minutes after
welding.

THERMAL PROTECTION

9. OVER TEMPERATURE LIGHT- If the welder
overheats due to blocked air flow, high ambient air
temperature, or exceeded duty cycle, an internal ther­mostat will open disabling the welding output and this
yellow light will illuminate. The cooling fans will contin­ue to run to cool the unit during this time. The light will
go out when the unit cools and the thermostat resets.
Once the light goes out, the machine will again
become available to weld.

Once the machine cools sufficiently the thermostats
are self-resetting. If the thermostat shutdown is caused

by excessive output or duty cycle and the fan is oper­ating normally, the power may be left on, and the reset
should occur within a 15 minute period. If the fan is not
functioning properly or the air intake louvers are
obstructed, then the input power must be removed and
the fan problem or air obstruction corrected.

OVERLOAD PROTECTION

The machine is electronically protected from producing
excessively high output currents. The output is limited
to 200 amps.

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PRECISION TIG 185

Section F-1 Section F-1

TABLE OF CONTENTS

- TROUBLESHOOTING & REPAIR SECTION -

Troubleshooting & Repair Section ........................................................................Section F

How to Use Troubleshooting Guide..............................................................................F-2

PC Board Troubleshooting Procedures and Replacement...........................................F-3

Troubleshooting Guide..................................................................................................F-4

Test Procedures

High Frequency Circuit Disable Procedure ..........................................................F-15

T1 Transformer Test ..............................................................................................F-17

Static SCR Test ....................................................................................................F-21

Active SCR Test ....................................................................................................F-25

Oscilloscope Waveforms

Normal Open Circuit Voltage Waveform-AC TIG Mode.......................................F-29

Normal Open Circuit Voltage Waveform-DC TIG Mode.......................................F-30

Normal Open Circuit Voltage Waveform-AC Stick Mode.....................................F-31

Normal Open Circuit Voltage Waveform-DC Stick Mode ....................................F-32

Typical Output Voltage Waveform-Machine Loaded AC TIG Mode.....................F-33

Typical Output Voltage Waveform-Machine Loaded DC TIG Mode ....................F-34

Typical Output Voltage Waveform-Machine Loaded AC Stick Mode ..................F-35

Typical Output Voltage Waveform-Machine Loaded DC Stick Mode..................F-36

Abnormal Open Circuit Voltage-DC TIG Mode One SCR not Functioning..........F-37

Replacement Procedures

SCR Bridge Assembly Removal and Replacement .............................................F-39

Polarity Switch Removal and Replacement .........................................................F-45

High Voltage Transformer Removal and Replacement ........................................F-49

Main Transformer and Output Choke Removal and Replacement ......................F-53

Retest after Repair ......................................................................................................F-57

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PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-2 F-2

CAUTION

This Troubleshooting Guide is provided to help
you locate and repair possible machine
malfunctions. Simply follow the three-step
procedure listed below.

Step 1. LOCATE PROBLEM (SYMPTOM). Look
under the column labeled “PROBLEM
(SYMPTOMS)”. This column describes possible
symptoms that the machine may exhibit. Find
the listing that best describes the symptom that
the machine is exhibiting. Symptoms are
grouped into three main categories: Feeding
Problems and Welding Problems.

Step 2. PERFORM EXTERNAL TESTS. The
second column, labeled “POSSIBLE AREAS OF
MISADJUSTMENT(S)”, lists the obvious external
possibilities that may contribute to the machine
symptom. Perform these tests/checks in the
order listed. In general, these tests can be
conducted without removing the case
wrap-around cover.

Step 3. PERFORM COMPONENT TESTS. The
last column, labeled “Recommended Course of
Action” lists the most likely components that may
have failed in your machine. It also specifies the
appropriate test procedure to verify that the
subject component is either good or bad. If there
are a number of possible components, check the
components in the order listed to eliminate one
possibility at a time until you locate the cause of
your problem.

All of the referenced test procedures referred to in
the Troubleshooting Guide are described in detail
at the end of this chapter. Refer to the
Troubleshooting and Repair Table of Contents to
locate each specific Test Procedure. All of the
referred to test points, components, terminal
strips, etc., can be found on the referenced
electrical wiring diagrams and schematics. Refer
to the Electrical Diagrams Section Table of
Contents to locate the appropriate diagram.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF. Perform High
Frequency Disable Procedure.

WARNING

PRECISION TIG 185

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TROUBLESHOOTING & REPAIR

F-3 F-3

Sometimes machine failures appear to be due to PC
board failures. These problems can sometimes be
traced to poor electrical connections. To avoid prob­lems when troubleshooting and replacing PC boards,
please use the following procedure:

1. Determine to the best of your technical ability
that the PC board is the most likely component
causing the failure symptom.

2. Check for loose connections at the PC board
to assure that the PC board is properly
connected.

3. If the problem persists, replace the suspect PC
board using standard practices to avoid static
electrical damage and electrical shock. Read
the warning inside the static resistant bag and
perform the following procedures:

PC board can be damaged by static electricity.

- Remove your body’s static
charge before opening the static­shielding bag. Wear an anti-static
wrist strap. For safety, use a 1
Meg ohm resistive cord connected
to a grounded part of the
equipment frame.

- If you don’t have a wrist strap,
touch an un-painted, grounded,
part of the equipment frame. Keep
touching the frame to prevent
static build-up. Be sure not to
touch any electrically live parts at
the same time.

- Tools which come in contact with the PC board must
be either conductive, anti-static or static-dissipative.

ELECTRIC SHOCK
can kill.

•

Have an electrician install and
service this equipment. Turn the
input power OFF at the fuse box
before working on equipment. Do
not touch electrically hot parts.

- Remove the PC board from the static-shielding bag
and place it directly into the equipment. Don’t set the
PC board on or near paper, plastic or cloth which
could have a static charge. If the PC board can’t be
installed immediately, put it back in the static-shield­ing bag.

- If the PC board uses protective shorting jumpers,
don’t remove them until installation is complete.

- If you return a PC board to The Lincoln Electric
Company for credit, it must be in the static-shielding
bag. This will prevent further damage and allow prop­er failure analysis.

4. Test the machine to determine if the failure

symptom has been corrected by the
replacement PC board.

NOTE: It is desirable to have a spare (known good)
PC board available for PC board troubleshooting.

NOTE

: Allow the machine to heat up so that all

electrical components can reach their operating
temperature.

5. Remove the replacement PC board and

substitute it with the original PC board to
recreate the original problem.

a. If the original problem does not reappear by

substituting the original board, then the PC
board was not the problem. Continue to look
for bad connections in the control wiring
harness, junction blocks, and terminal strips.

b. If the original problem is recreated by the

substitution of the original board, then the PC
board was the problem. Reinstall the
replacement PC board and test the machine.

6. Always indicate that this procedure was

followed when warranty reports are to be
submitted.

NOTE

: Following this procedure and writing on the

warranty report, “INSTALLED AND SWITCHED PC
BOARDS TO VERIFY PROBLEM,” will help avoid
denial of legitimate PC board warranty claims.

PC BOARD TROUBLESHOOTING PROCEDURES

ATTENTION
Static-Sensitive
Devices
Handle only at
Static-Safe
Workstations

WARNING

CAUTION

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TROUBLESHOOTING & REPAIR

F-4 F-4

PRECISION TIG 185

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

OUTPUT PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

Machine is dead. No output - No fan

The fan runs normally. No output from the machine in either Stick or TIG modes.

1. Make sure that the input power
switch is in the "ON" position and
the machine is plugged in.

2. Check the input voltage at the
machine. Input voltage must
match the rating plate and volt­age connection. Refer to
Reconnect Procedure in the
Installation section of this manu­al.

3. Blown or missing fuses in the
input line.

1. Check for proper input voltages
per nameplate and voltage
reconnect configuration.

2. Check to make sure the polarity
switch is in the proper position
and functioning correctly.

1. Check the input power switch
and associated wires for loose or
faulty connections.

2. Perform the T1 Transformer
Test.

1. Check for loose or faulty connec­tions on the heavy current carry­ing leads. (polarity switch, output
choke output terminals etc.)

2. Perform the T1 Transformer
Test.

3. Perform the SCR Bridge Test.

4. Check current control R1 for
proper operation. Normal resis­tance is 10,000 ohms. Also
check associated leads for loose
or faulty connections.

5. The control board may be faulty.
Replace.

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

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TROUBLESHOOTING & REPAIR

F-5 F-5

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

PRECISION TIG 185

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

OUTPUT PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

Fan runs - No output from machine in either Stick or TIG modes and the yellow light on the control panel is on.

The machine does not respond (no
gas flow, no high frequency and no
open circuit voltage) when the arc
start switch or Amptrol is activated ­fan is working normally.

1. The welding application may
have exceeded the recommend­ed duty cycle. Allow the unit to
run until the fan cools the unit
and the yellow light goes out.

2. The air louvers may be blocked.
Remove air obstruction and allow
unit to cool.

1. Make certain the machine is in
the TIG mode.

2. The Amptrol may be defective.
Check for continuity(zero ohms)
between pins "D" and "E" on
cable connector when the
Amptrol is depressed.

1. One of the thermostats may be
faulty. Check or replace. See
wiring diagram.

2. Check for loose or faulty wires on
the thermostats and associated
circuitry. See wiring diagram.

1. Check the continuity (zero ohms)
of the leads between the remote
receptacle and plug J5 on the
control board. See wiring dia­gram.

2. Perform the T1 Transformer
Test.

3. The control board may be faulty.
Replace.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-6 F-6

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

OUTPUT PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

Machine regularly over heats - ther­mostat opens. Yellow light on front
panel glows. The fan runs but the
machine has no output.

The machine does not have output in the Stick mode. The machine operates correctly in the TIG mode.

Machine regularly over heats - ther­mostat opens. Yellow light on front
panel glows. The fan runs but the
machine has no output.

The machine does not have output
in the Stick mode. The machine
operates correctly in the TIG mode.

1. The thermostat(s) may be faulty.
Check or replace.

2. The control board may be faulty.

1. Check the Stick/TIG switch(S3)
and associated leads. See
wiring diagram.

2. The control board may be faulty.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-7 F-7

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

OUTPUT PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

Machine welds at a very low output
regardless of the current control set­ting.

The machine welds at a very high
output regardless of the current con­trol setting.

1. If welding in the TIG mode the
remote control device may be
defective.

2. Make certain the input line volt­age is correct for the machine
reconnect configuration.

3. Check the welding cables and or
torch for loose or faulty connec­tions.

1. If welding in the TIG mode the
remote control device may be
defective.

1. Check the polarity switch and
associated leads.

2. Check the interior connections of
the heavy current carrying leads.

3. Perform the SCR Bridge Test.

4. Perform the T1 Transformer
Test.

5. Check the current control for
proper operation. Normal resis­tance is 10k ohms. See wiring
diagram.

6. The control board may be faulty.

1. Perform the SCR Bridge Test.

2. Perform the T1 Transformer
Test.

3. Check the current control for
proper operation. Normal resis­tance is 10k ohms. See wiring
diagram.

4. The control board may be faulty.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-8 F-8

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

TIG MODE PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

Machine output is intermittently lost. Gas flow and high frequency are also interrupted.

1. The problem may be caused by
high frequency interference.
Make sure that the machine is
grounded properly according to
the installation instructions. If
there are other high frequency
sources in the area, make certain
that they are grounded properly.

2. Make sure the Amptrol is operat­ing properly.

3. Check to make sure that the
input voltage is correct for the
machine reconnect configuration.
Refer to Reconnect Procedure
in the Installation section of this
manual.

1. Check for loose or faulty connec­tion on the leads between the
remote receptacle and plug J5
on the control board. See wiring
diagram.

2. Check the plugs on the control
board for loose connections.

3. The control board may be faulty.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-9 F-9

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

TIG MODE PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

The arc "flutters" when TIG welding.

The arc "pulsates" when AC TIG welding.

1. The tungsten electrode may be
too large in diameter for the cur­rent setting.

2. The tungsten tip may not be
"sharp" enough.

3. The gas shielding may be insuffi­cient. Increase the gas flow and
or reduce the tungsten stickout
beyond the gas cup.

4. Check for contaminated gas or
leaks in the gas line, torch, or
connections.

5. If a helium blend is used as a
shielding gas then reduce the
percentage of helium.

1. Make sure the gas and proce­dure are correct for the process
being used.

1. Check the polarity switch for
proper operation and loose or
faulty lead connections. See
wiring diagram.

2. Perform the SCR Bridge Test.

3. Check for loose or faulty connec­tions at the shunt. ( leads #221
and #222 ).

4. Check components R3 and C4 in
the high voltage transformer pri­mary circuit. Replace if neces­sary. See wiring diagram.

5. The control board may be faulty.
Replace.

1. Check the micro switch S2A on
the polarity switch. It may be
stuck closed. See wiring dia­gram.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-10 F-10

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TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

TIG WELDING PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

Black areas along weld bead.

Weak high frequency - machine has normal welding.

1. Clean any oily or organic conta­mination from the work piece.

2. Tungsten electrode may be cont­aminated. Replace or sharpen.

3. Check for contaminated gas or
leaks in the gas line, torch, or
associated connections.

4. The gas shielding may be insuffi­cient. Increase gas flow: reduce
tungsten stickout beyond the gas
cup.

1. Check for loose or faulty connec­tions at the torch and/or welding
cables.

2. The gas shielding may be insuffi­cient. Increase gas flow: reduce
tungsten stickout beyond the gas
cup.

3. Check spark gap operation and
setting. Normal is (0.015").
Refer to Maintenance section of
this manual.

4. The work and electrode cables
may be in poor condition allowing
the high frequency to "leak off".
Use good quality cables with a
high natural rubber content, such
as Lincoln Stable Arc Cable.
Cables should be as short as
possible.

1. This may be a welding proce­dure problem.

Contact The Lincoln Electric Service
Department, 1-888-935-3877.

1. Make sure that 115VAC is being
applied to the primary of the high
voltage transformer (T3). See
wiring diagram.

2. Check for any open or arcing
high frequency component.
Replace as required.

(Examples: C3, R3, C4)

3. If spark is weak at the spark gap,
check or replace the high fre­quency circuit.

(Examples: T3, L3, L4).

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-11 F-11

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Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

TIG WELDING PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

High frequency "spark" is present at tungsten electrode, but operator is unable to establish a welding arc. Machine has normal open circuit voltage. Refer to Technical Specifications in the Installation Chapter.

1. The torch may be faulty. Check
or replace.

2. The current control may be set
too low.

3. The tungsten electrode may be
contaminated. Replace or sharp­en.

4. The electrode may be too large
for the process.

5. If a helium blend is being used
as a shielding gas, then reduce
the percentage of helium.

6. Check the welding cables for
loose or faulty connections.

1. This may be a welding procedure
problem.

Contact The Lincoln Electric Service
Department 1-888-935-3877.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-12 F-12

Return to Section TOC Return to Section TOC Return to Section TOC Return to Section TOC

Return to Master TOC Return to Master TOC Return to Master TOC Return to Master TOC

TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

TIG WELDING PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

No high frequency. Machine is in
the TIG mode and has normal out­put.

No gas flow when Amptrol is activat­ed in the TIG mode. Machine has
normal output - fan runs.
A "click" can be heard indicating that
the gas solenoid valve is operating.

1. If the machine location is in a
highly dirty environment with con­ductive contaminants, check and
clean the spark gap with a low
pressure air stream per the main­tenance instructions.

2. Check spark gap operation and

setting. Normal is (0.020").
Refer to Maintenance section of
this manual.

1. The gas supply is either empty or
not turned on.

2. The flow regulator may be set
too low.

3. Check the gas hose for kinks or
blockages.

4. Check the filter screen inside gas
inlet fitting to solenoid valve.

1. Check the high voltage trans­former (T3). The normal resis­tance of the secondary winding
of the high voltage transformer is

12.5k ohms.

ELECTRIC SHOCK CAN
KILL. When 115VAC is

applied to the primary of
T3. Avery high voltage is devel­oped on the secondary winding.
For assistance call the Lincoln
Electric Service Department 1-888­935-3877.

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

2. Check the values of R3, and C4.

3. Perform the T1 Transformer Test.

4. The control board may be faulty.

Replace.

1. Possible gas supply problems.
Consult your local welder/gas dis-

tributor.

WARNING

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-13 F-13

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TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

TIG WELDING PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

When AC TIG welding, the arc is
erratic and there is a loss of "clean­ing" of the work piece.

The end of the tungsten electrode melts away.

1. The tungsten electrode may be
too small for the process. Use a
larger diameter tungsten or a
pure tungsten.

2. If a helium blend is used as a
shielding gas, then reduce the
percentage of helium.

1. The welding current is too high
for the electrode type and or
size. See Table B.1 in the
Operation Section.

1. Check components R3 and C4 in
the high voltage transformer pri­mary circuit.

2. Perform the SCR Bridge Test.

1. This may be a welding procedure
problem.

Contact The Lincoln Electric Service
Department 1-888-935-3877.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-14 F-14

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TROUBLESHOOTING GUIDE Observe Safety Guidelines

detailed in the beginning of this manual.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con­tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-888-935-3877.

STICK WELDING PROBLEMS

PROBLEMS

(SYMPTOMS)

POSSIBLE AREAS OF

MISADJUSTMENT(S)

RECOMMENDED

COURSE OF ACTION

Stick electrode "Blasts Off" when arc is struck.

The stick electrode "sticks" in the puddle.

Variable or sluggish welding arc when welding in the Stick mode.

1. Weld current may be set too high
for electrode size. Reduce cur­rent control setting, or use a larg­er diameter electrode.

1. The weld current may be set too
low. Increase the current control
setting or use a smaller diameter
electrode.

1. Check work and electrode cables
for loose or poor connections.

2. The weld cables may be too small

or too long to permit the desired
current to flow.

3. The weld current may be set too
low.

1. Perform the SCR Bridge Test.

2. The control board may be faulty.
Replace.

1. Check the polarity switch for
excessive wear or faulty connec­tions.

2. Check interior connection of the
heavy current carrying leads.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-15 F-15

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Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger
to the technician or machine operator and will invalidate your factory warranty . For
your safety and to avoid electrical shock, please observe all safety notes and pre­cautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per­form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

WARNING

HIGH FREQUENCY CIRCUIT DISABLE PROCEDURE

TEST DESCRIPTION

This procedure will disable the high frequency circuit. The technician will then be able to
take voltage measurements without the possibility of high frequency damage to his test
equipment.

MATERIALS NEEDED

3/8” Nutdriver
5/64” Allen type wrench
.020” feeler gauge

HIGH VOLTAGE IS STILLPRESENT IN THE HIGH FREQUENCY CIRCUIT.

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

WARNING

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-16 F-16

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PROCEDURE

1. Remove input power to the TIG185
machine.

2. Using the 3/8” nutdriver remove the
right side panel.

3. Locate the Spark Gap Assembly at
the right side of the machine. See
Figure F.1.

4. With the 5/64” Allen type wrench
loosen the set screw holding the
upper electrode in place.

5. Increase the distance between the
electrodes to at least 3/8” by sliding
one electrode away from the other
electrode. Secure the one electrode
in this position.

6. This should disable the high frequen­cy circuit. Visually check to make

sure high frequency sparking is
NOT present before connecting
any test equipment to the TIG 185
machine.

7. When voltage testing and scope
measurements are complete reset
the spark gap electrodes to .020” air
gap. Tighten the set screw using the
5/64” Allen wrench.

HIGH FREQUENCY CIRCUIT DISABLE PROCEDURE

.015 Spark Gap

LEFT SIDE OF MACHINE

FIGURE F.1 SPARK GAP ASSEMBLY

.020

Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger
to the technician or machine operator and will invalidate your factory warranty . For
your safety and to avoid electrical shock, please observe all safety notes and pre­cautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per­form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

PRECISION TIG 185

F-17 F-17

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WARNING

TROUBLESHOOTING & REPAIR

T1 TRANSFORMER TEST

TEST DESCRIPTION

This procedure will determine if the correct voltage is being applied to the primary of the
T1 transformer and also if the correct voltages are being induced on the secondary
windings of the transformer.

MATERIALS NEEDED

Volt/Ohm Meter

Precision TIG 185 Wiring Diagrams
3/8” nutdriver

PRECISION TIG 185

F-18 F-18

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TROUBLESHOOTING & REPAIR

T1 TRANSFORMER TEST (continued)

TEST PROCEDURE

1. Remove main supply power to the
machine.

2. Using the 3/8” nutdriver remove the
case wrap-around cover.

3. Locate plugs J3 and J4 on the

control board. See Figure F.2.

4. Carefully apply the correct input
power making certain the reconnect
configuration at the input switch is
correct for the input voltage applied.
Turn the TIG 185 ON.

5. Using the voltmeter carefully test for
the correct transformer secondary
voltages per Table F.1.

PRECISION TIG 185 CONTROL BOARD

J2

J3

J4

PIN 4 (LEAD #201)

PIN 3 (LEAD #204

)

PIN 7 (LEAD #209)
PIN 8 (LEAD #210)

PIN 3 (LEAD #232)
PIN 2 (LEAD #260)

FIGURE F.2 - Plugs J3 & J4 on Control Board

PRECISION TIG 185

F-19 F-19

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TROUBLESHOOTING & REPAIR

T1 TRANSFORMER TEST (continued)

6. If all of the secondary voltages are
correct the T1 transformer is func­tioning properly.

A. If all of the secondary voltages

are missing or incorrect make
certain that the correct input volt­age is being applied to the correct
primary leads. See Table F.1.

B. If the correct input voltage is

being applied to the primary leads
and any or all of the secondary
voltages are incorrect the T1
transformer may faulty. See

Main Transformer and Output

Choke Removal and
Replacement. Also check the

leads for broken or loose connec­tions between plugs J3, J4 and
the T1 transformer.

7. Replace case wrap-around cover.

TEST POINTS ACCEPTABLE VOLTAGES

SECONDARY WINDINGS SECONDARY VOLTAGES

PLUG J3 PIN 8 (LEAD #210)

TO 18VAC

PLUG J3 PIN 7 (LEAD #209)

PLUG J3 PIN 4 (LEAD #201)

TO 18VAC

PLUG J3 PIN 3 (LEAD #204)
PLUG J4 PIN 2 (LEAD #260)

CHECK DURING FIRST 5 SECONDS OF POWER UP

TO 115VAC

PLUG J4 PIN 3 (LEAD #232)

X1 TO X2 80 VAC

PRIMARY WINDINGS PRIMARY VOLTAGES

H1 TO H2 208VAC
H1 TO H3 230VAC

TABLE F.1 T1 TRANSFORMER VOLTAGE

NOTE: If the input voltages vary the secondary voltages will vary accordingly.

PRECISION TIG 185

NOTES

F-20 F-20

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PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-21 F-21

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Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger
to the technician or machine operator and will invalidate your factory warranty . For
your safety and to avoid electrical shock, please observe all safety notes and pre­cautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per­form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

WARNING

STATIC SCR TEST

TEST DESCRIPTION

This procedure is a quick check to determine if an SCR is shorted or “leaky”. See
machine waveform section for normal and abnormal SCR waveforms.

MATERIALS NEEDED

Volt/Ohm Meter (Analog)

Precision TIG 185 Wiring Diagrams
3/8” nutdriver
SCR Heat Sink Assembly Drawing

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-22 F-22

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TEST PROCEDURE

1. Remove main supply power to the
TIG 185 and remove the case wrap­around cover.

2. Locate and remove plug J2 from the
control board. See Figure F.3.

STATIC SCR TEST (continued)

PLUG J2 REMOVED

PRECISION TIG 185 CONTROL

J2

J3

J4

Figure F.3 - Plug J2 Location on Control Board

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-23 F-23

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3. Using an analog ohmmeter test the
resistance from anode to cathode of
SCR1. Reverse the meter leads and
check from cathode to anode of
SCR1. See Figure F.4. If a low resis­tance is indicated in either direction
SCR1 is faulty. Replace SCR Bridge
Assembly. See SCR Bridge

Assembly Removal and
Replacement.

4. Repeat Step #3 testing SCR2, SCR3
and SCR4.

5. The further check the SCR’s func­tions use an SCR tester and proceed
to the Active SCR Test.

STATIC SCR TEST (continued)

SCR1 ANODE

SCR1 CATHODE/SCR2 ANODE

SCR2 CATHODE

SCR3 CATHODE

SCR4 ANODE

SCR3 ANODE/SCR4 CATHODE

FIGURE F.4 SCR TEST POINTS

PRECISION TIG 185

NOTES

F-24 F-24

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PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-25 F-25

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Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger
to the technician or machine operator and will invalidate your factory warranty . For
your safety and to avoid electrical shock, please observe all safety notes and pre­cautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per­form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

WARNING

ACTIVE SCR TEST

TEST DESCRIPTION

This procedure will determine if the device is able to be gated “ON” and conduct current
from anode to cathode.

MATERIALS NEEDED

An SCR tester as outlined in this procedure.

Precision TIG 185 Wiring Diagrams
3/8” nutdriver

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-26 F-26

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TEST PROCEDURE

1. Remove main supply power to the
TIG 185 machine.

2. Locate and remove plug J2 from the
control board. See Figure F.3.

3. Perform test procedure as outlined in
Figure F.5. Repeat test for all four
SCRs. See Figure F.6.

4. Construct the circuit outlined in Figure
F.5. One 6V lantern battery can be
used. Resistor values are ±10%. The
voltmeter scale should be low,
approximately 0-5 or 0-10 volts.

5. Battery

T

est - Check the battery by
shorting leads (A) and (C) and then
close switch SW-1. Re-place battery if
voltage is less than 4.5 volts.

ACTIVE SCR TEST (continued)

FIGURE F.5 ACTIVE SCR TEST SETUP

SW1

R2

SW2

R1

A

G

C

V

SCR
under
test

R1= 4 ohms /10 watts
R2= 3 ohms/ 10 watts

6volt
Lantern
Battery

To test SCRs construct the circuit outlined above.
Resistor values are plus or minus ten percent. The
voltmeter scale should be low, approximately 0-5 or
0-10 volts DC.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-27 F-27

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6. Connect SCR into the test circuit as
shown (A) lead to anode (C) lead to
cathode and (G) lead to the gate.

7. Close switch SW-1 (switch SW-2
should open), voltmeter should read
zero. If the voltmeter reads higher
than zero the SCR is shorted.

8. With switch SW-1 closed, close
switch SW-2 for two seconds and
release. The voltmeter should read 3
to 6 volts before and after switch SW­2 is released. If the voltmeter does not
read, or reads only while SW-2 is
depressed, the SCR or battery is
defective (repeat Battery Test
Procedure above).

9. Open switch SW-1, disconnect the
gate lead (G) and reverse the (A) and
(C) leads on the SCR. Close switch
SW-1. The voltmeter should read
zero. If the voltage is higher than
zero, the SCR is shorted.

10. Replace SCR Bridge Assembly if

any SCRs do not pass the test in
Step #3. See SCR Bridge

Assembly Removal and
Replacement.

11. Replace plug J2 into the control

board.

12. Replace the case wrap-around

cover.

ACTIVE SCR TEST (continued)

SCR1 ANODE

SCR1 CATHODE/SCR2 ANODE

SCR2 CATHODE

SCR3 CATHODE

SCR4 ANODE

SCR3 ANODE/SCR4 CATHODE

FIGURE F.6 SCR GATE LOCATIONS

3

4

2

1

SCR1

SCR4SCR3

SCR2

S24018-4 (INSERTION SIDE)

PLUG J2

SCR GATE LEADS/TEST POINTS

PRECISION TIG 185

NOTES

F-28 F-28

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PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-29 F-29

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NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM

AC TIG MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

50 V

2 ms

0 V

This is the typical AC output voltage wave­form generated from a properly operating
machine. Note that each vertical division
represents 50 volts and that each horizontal
division represents 2 milliseconds in time.

Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................50 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-30 F-30

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NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM

DC TIG MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

50 V

2 ms

0 V

This is the typical DC (+) output voltage
waveform generated from a properly operat­ing machine. Note that each vertical division
represents 50 volts and that each horizontal
division represents 2 milliseconds in time.

Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................50 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-31 F-31

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NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM

AC STICK MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

50 V

2 ms

0 V

This is the typical AC output voltage wave­form generated from a properly operating
machine. Note that each vertical division
represents 50 volts and that each horizontal
division represents 2 milliseconds in time.

Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................50 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-32 F-32

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NORMAL OPEN CIRCUIT VOLTAGE WAVEFORM

DC STICK MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

50 V

2 ms

0 V

This is the typical DC (+) output voltage
waveform generated from a properly operat­ing machine. Note that each vertical division
represents 50 volts and that each horizontal
division represents 2 milliseconds in time.

Note: Scope probes connected at machine
output studs: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................50 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-33 F-33

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TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED

AC TIG MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

10 V

2 ms

0 V

MACHINE LOADED TO 180 AMPS AT
16VDC.

This is the typical AC output voltage wave­form generated from a properly operating
machine. Note that each vertical division
represents 10 volts and that each horizontal
division represents 2 milliseconds in time.
The machine was loaded with a resistance
grid bank. The grid load meters read 180
amps and 16VDC

Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................10 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-34 F-34

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TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED

DC TIG MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

10 V

2 ms

0 V

MACHINE LOADED TO 180 AMPS AT
16VDC.

This is the typical DC (+) output voltage
waveform generated from a properly operat­ing machine. Note that each vertical division
represents 10 volts and that each horizontal
division represents 2 milliseconds in time.
The machine was loaded with a resistance
grid bank. The grid load meters read 180
amps and 16VDC

Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................10 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-35 F-35

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TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED

AC STICK MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

10 V

2 ms

0 V

MACHINE LOADED TO 180 AMPS AT
26VDC.

This is the typical AC output voltage wave­form generated from a properly operating
machine. Note that each vertical division
represents 10 volts and that each horizontal
division represents 2 milliseconds in time.
The machine was loaded with a resistance
grid bank. The grid load meters read 180
amps and 26VDC

Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................10 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-36 F-36

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TYPICAL OUTPUT VOLTAGE WAVEFORM - MACHINE LOADED

DC STICK MODE

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

10 V

2 ms

0 V

MACHINE LOADED TO 180 AMPS AT
26VDC.

This is the typical AC output voltage wave­form generated from a properly operating
machine. Note that each vertical division
represents 10 volts and that each horizontal
division represents 2 milliseconds in time.
The machine was loaded with a resistance
grid bank. The grid load meters read 180
amps and 26VDC

Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................10 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-37 F-37

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ABNORMAL OPEN CIRCUIT VOLTAGE - DC TIG MODE

ONE OUTPUT SCR NOT FUNCTIONING

CAUTION

HIGH VOLTAGE / HIGH FREQUENCY can damage test equipment.

• Perform all voltage and waveform checks with high frequency circuit OFF.

• Perform High Frequency Disable Procedure.

____________________________________________________________________

50 V

2 ms

0 V

This is NOT the typical DC (+) output voltage
waveform. One output SCR is not function­ing. Note the “gap”in the waveform. One
SCR gate was disconnected to simulate an
open or non-functioning output SCR. Note
that each vertical division represents 50
volts and that each horizontal division repre­sents 2 milliseconds in time.

Note: Scope probes connected at machine
output terminals: (+) probe to electrode, (–)
probe to work.

Volts/Div. ...............................50 V/Div.

Horizontal Sweep.................2 ms/Div.

Coupling.........................................DC

Trigger.....................................Internal

SCOPE SETTINGS

PRECISION TIG 185

NOTES

F-38 F-38

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PRECISION TIG 185

F-39 F-39

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TROUBLESHOOTING AND REPAIR

Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger
to the technician or machine operator and will invalidate your factory warranty . For
your safety and to avoid electrical shock, please observe all safety notes and pre­cautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per­form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

WARNING

SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE

TEST DESCRIPTION

This procedure will aid the technician in the removal and replacement of the SCR
assembly

MATERIALS NEEDED

5/16” nutdriver

3/8” nutdriver

Needle nose pliers

7/16” Wrench

3/8” Wrench

Slot head screwdriver

Dow Corning 340 Heat Sink compound

PRECISION TIG 185

F-40 F-40

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TROUBLESHOOTING AND REPAIR

SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

PROCEDURE

1. Remove input power to the TIG 185
machine.

2. Using the 3/8” nutdriver remove the
case wrap-around cover.

3. With the slot head screwdriver
loosen the input cable strain relief to
allow movement of case back.

4. Using the 3/8” nutdriver remove the
two lower screws from the case back.
See Figure F.7.

5. With the 5/16” nutdriver remove the
two screws holding the case back to
the internal divider panel. See Figure
F.7.

6. Remove the gas hose from the gas
solenoid valve.

7. Carefully pull the case back and fan
assembly away to allow access to
the SCR Bridge Assembly. Support
the case back so as not to stress the
fan motor leads. It is not necessary
to disconnect the fan motor leads.

8. Using the 5/16” nutdriver remove the
two screws holding the front panel
assembly to the base. See Figure
F.8.

FIGURE F.7 CASE BACK MOUNTING SCREWS

REAR PANEL
MOUNTING
SCREWS

PRECISION TIG 185

F-41 F-41

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TROUBLESHOOTING AND REPAIR

SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

9. Remove plug J2 from the control
board. (See Figure F.9.) Also
remove plug and lead harness from
internal divider panel.

10. Carefully slide the internal divider

panel away a few inches to allow
access to the SCR bridge assem­bly.

11. Using the 7/16” wrench disconnect

the diode pigtail connection from the
polarity switch lead. See Figure
F.10. Cut any necessary cable ties
and remove insulating sleeving.

Note placement of sleeving and cable
ties for reassembly.

12. Using the 7/16” wrench remove the

X2 secondary transformer lead from
the left side AC SCR heat sink.

13. With the 7/16” wrench remove the
shunt from the SCR bridge left side
negative heat sink.

14. Using the 7/16” wrench remove the
polarity switch lead from the right
side AC SCR heat sink.

15. Using the 7/16” wrench remove the
positive lead from the right side
positive heat sink.

FIGURE F.8 FRONT PANEL MOUNTING SCREWS

FRONT PANEL
MOUNTING
SCREWS

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-42 F-42

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SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

FIGURE F.9 PLUG J2 ON CONTROL BOARD

PLUG J2 REMOVED

PRECISION TIG 185 CONTROL

J2

J3

J4

FIGURE F.10 DIODE PIGTAIL CONNECTION TO POLARITY SWITCH LEAD.

DIODE
PIGTAIL
CONNECTION

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-43 F-43

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SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

16. With the 3/8” wrench remove the
four mounting screws holding the
SCR bridge assembly to the main
transformer frame. Note insulator
placement.

17. Carefully remove the SCR bridge
assembly from the TIG 185 cutting
any necessary cable ties.

REPLACEMENT PROCEDURE

1. Carefully place the new SCR bridge

assembly in position in the TIG 185.

2. Using the 3/8” wrench install the four

mounting screws taking special care
that the insulators are in the correct
positions.

USE DOW CORNING 340 HEAT SINK
COMPOUND ON ALL ALUMINUM
CONNECTIONS

3. Assemble the positive lead to the

right side positive heat sink.

4. Assemble the lead from the polarity

switch to the right side AC heat sink.
Note: Also connect lead #216

5. Assemble the shunt to the SCR

bridge left side negative heat sink.

6. Assemble the X2 secondary trans-

former lead to the left side AC SCR
heat sink. Note: Also connect lead
#217

7. Assemble the diode pigtail lead to

the polarity switch lead. See Figure
F.10. Be sure to replace sleeving
and secure with cable ties. Position
with harness and secure with cable
ties.

8. Replace any previously removed

cable ties.

9. Position the internal divider panel
and secure with the screws previous­ly removed.

10. Install the J2 plug into the control

board and position the harness in
the internal divider panel.

11. Position and install the case back

and secure with the screws previ­ously removed.

12. Install the gas hose onto the sole-

noid valve.

13. Tighten the input cable strain relief.

14. Assemble the case wrap-around

cover.

PRECISION TIG 185

NOTES

F-44 F-44

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PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-45 F-45

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Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger
to the technician or machine operator and will invalidate your factory warranty . For
your safety and to avoid electrical shock, please observe all safety notes and pre­cautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per­form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

WARNING

POLARITY SWITCH

REMOVAL AND REPLACEMENT PROCEDURE

TEST DESCRIPTION

This procedure will aid the technician in the removal and replacement of the polarity
switch.

MATERIALS NEEDED

3/8” Nutdriver

1/2” Wrench

7/16” Wrench

Phillips head screwdriver

5/64” Allen type Wrench

Needle nose pliers

Slot head screwdriver (2 required)

Wiring diagram

POLARITY SWITCH

REMOVAL AND REPLACEMENT PROCEDURE

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-46 F-46

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POLARITY SWITCH

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

REMOVAL PROCEDURE

1. Remove the input power to the TIG
185 machine.

2. Using the 3/8” nutdriver remove the
case wrap-around cover.

3. Using the 3/32” Allen type wrench
remove the output control knob.

4. Using the Phillips head screwdriver
remove the screw from the polarity
switch handle.

5. With the 2 slot head screwdrivers
carefully pry the polarity switch han­dle from the shaft.

6. Remove the five plastic snap rivets
holding the name plate to the case
front. These can be removed by gen­tly prying at the rivet between the
name plate and the case front.

7. Remove the name plate.

8. With the 1/2” wrench remove the
“positive” flex lead from the polarity
switch. See wiring diagram. Label
lead and connection point for
reassembly.

9. With the 1/2” wrench remove the
“AC” flex lead from the polarity
switch. This lead connects to the AC
plate on the SCR bridge. See wiring
diagram. Label lead and connection
point for reassembly.

10. Using the 1/2” wrench remove the

flex lead from the rear gang of the
polarity switch. This lead connects
to the D1 diode on the SCR bridge.
See wiring diagram. Label lead and
connection point for reassembly.

11. Using the 1/2” wrench remove the

flat copper lead from the polarity
switch. This lead connects to the
high frequency transformer coil and
the by-pass board. See wiring
diagram. Label lead and connec-

tion point for reassembly.

12. Using the 1/2” wrench remove the
other flat copper lead from the
polarity switch. This lead connects
to the lower terminal on the by-pass
board and the “work” lead. See
wiring diagram. Label lead and
connection point for reassembly.

13. Using the 1/2” wrench remove the
choke lead from the polarity switch.
See wiring diagram. Label lead and
connection point for reassembly.

14. With the 1/2” wrench remove the X1
secondary lead from the polarity
switch. See wiring diagram. Label
lead and connection point for
reassembly.

15. With the 7/16” wrench remove the
two nuts and washers that hold the
polarity switch to the front panel.

16. Carefully rotate the polarity switch
assembly to gain access to the
micro-switch.

17. Carefully unsolder the two leads
(#311 and #312) from the micro­switch located on the polarity switch
assembly. See wiring diagram.
Label leads and connection points
for reassembly.

18. Carefully remove the polarity switch
assembly from the machine.

POLARITY SWITCH

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-47 F-47

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POLARITY SWITCH

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

REPLACEMENT PROCEDURE

1. Carefully position the new polarity
switch in position on the front panel.
Make certain the micro-switch is
assembled to the polarity switch cor­rectly.

2. Solder leads #311 and #312 to the
micro -switch.

3. Assemble and tighten the two nuts
and washers that hold the polarity
switch to the front panel.

4. Assemble the X1 secondary lead to
the polarity switch. Make certain
washers are in place and the nut is
tight.

5. Assemble the choke lead to the
polarity switch. Make certain wash­ers are in place and the nut is tight.

6. Assemble the flat copper leads to the
polarity switch. Make certain they
are connected to the proper termi­nals and the nuts are tightened.

7. Assemble the flex lead from diode
D1 to the rear gang of the polarity
switch. Make certain washers are in
place and the nut is tight.

8. Assemble the flex lead from the AC
bridge plate to the polarity switch.
Make certain washers are in place
and the nut is tight.

9. Assemble the “positive” flex lead to
the polarity switch. Make certain
washers are in place and the nut is
tight.

10. Clear the leads and check for

“shorted” or “grounded” leads.

11. Position the name plate and fasten

to the front with the previously
removed snap rivets.

12. Assemble the polarity switch handle

in place with the Phillips head screw
and check for correct switch opera­tion.

13. Using the Allen type wrench replace

the output control knob.

14. Replace the case wrap-around

cover.

PRECISION TIG 185

NOTES

F-48 F-48

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PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-49 F-49

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Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger
to the technician or machine operator and will invalidate your factory warranty . For
your safety and to avoid electrical shock, please observe all safety notes and pre­cautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per­form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

WARNING

TEST DESCRIPTION

This procedure will aid the technician in the removal and replacement of the high voltage
transformer.

MATERIALS NEEDED

3/8” Nutdriver

Phillips head screwdriver

Needle nose pliers

Wire cutters

HIGH VOLTAGE TRANSFORMER

REMOVAL AND REPLACEMENT PROCEDURE

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-50 F-50

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REMOVAL PROCEDURE

1. Remove input power to the TIG 185
machine.

2. Using the 3/8” nutdriver remove the case

wrap-around cover.

3. With the needle nose pliers remove the

two secondary leads from the quick-con­nects on the high frequency arc starter
board assembly. See Figure F.11.

4. Disconnect the in-line splice quick con-

nect from one primary lead to lead #231A.
Cut any necessary cable ties.

5. Remove the lead splice from the other pri-

mary lead that is connected to lead #236
and the C4 capacitor. See wiring dia­gram. Cut any necessary cable ties.

6. Using the phillips head screwdriver
remove the front mounting screws from
the base of the high voltage transformer.
Take note of insulator placement for
reassembly. NOTE: On some machines
the mounting screw configuration may be
different.

7. With phillips head screwdriver loosen the
two rear mounting screws.

8. Carefully slide the transformer forward
and remove from the TIG 185 machine.

FIGURE F.11 SECONDARY LEADS AT HIGH FREQUENCY STARTER BOARD

TRANSFORMER
SECONDARY
LEADS

HIGH VOLTAGE TRANSFORMER

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

HIGH VOLTAGE TRANSFORMER

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-51 F-51

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HIGH VOLTAGE TRANSFORMER

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

REPLACEMENT PROCEDURE

1. Carefully position the new high volt­age transformer in place in the two
rear mounting insulators. See Figure
F.12.

2. Install the front mounting insulators
and mounting screw.

3. Using the phillips head screwdriver
tighten all four mounting screws mak­ing certain the insulators are posi­tioned correctly.

4. Reconnect the two primary leads.

5. Reconnect the two secondary leads
to the high frequency arc starter
board assembly.

6. Replace any previously removed
cable ties.

7. Replace the case wrap-around
cover.

FIGURE F.12 HIGH VOLTAGE TRANSFORMER MOUNTING INSULATORS

FRONT MOUNTING
INSULATORS

SLOTTED REAR
MOUNTING INSULATORS

NOTE: On some machines the
mounting screw configuration may be
different.

PRECISION TIG 185

NOTES

F-52 F-52

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PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-53 F-53

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Service and repair should be performed by only Lincoln Electric factory trained
personnel. Unauthorized repairs performed on this equipment may result in danger
to the technician or machine operator and will invalidate your factory warranty . For
your safety and to avoid electrical shock, please observe all safety notes and pre­cautions detailed throughout this manual.

If for any reason you do not understand the test procedures or are unable to per­form the test / repairs safely, contact the Lincoln Electric Service Department for
electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.

WARNING

TEST DESCRIPTION

This procedure will aid the technician in the removal and replacement of the main
transformer and choke assembly.

MATERIALS NEEDED

3/8” Nutdriver

1/2” Wrench

Wire cutters

MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-54 F-54

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MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

REMOVAL PROCEDURE

1. Remove input power to the TIG 185
machine.

2. Perform the SCR Bridge Assembly
Removal Procedure.

3. Unsolder the two 115VAC leads and
leads B231 and B232 from the main
transformer leads. Label leads for
reassembly. See wiring diagram.

4. Unsolder leads W201 and W204
from the main transformer leads.
Label leads for reassembly. See
wiring diagram.

5. Unsolder leads R209 and U210 from
the main transformer leads. Label
leads for reassembly . See wiring dia­gram.

6. Using the 1/2” wrench remove the
shunt assembly from the choke lead.

7. With the 3/8” wrench remove the H1,
H2 or H3 lead from the input power
switch. See wiring diagram. Label
the leads and connection points for
reassembly. Cut any necessary
cable ties.

8. Remove plug J3 from the control
board and push through the interior
divider panel.

9. Using the 1/2” wrench remove the
choke lead from the polarity switch.
See wiring diagram. Label lead and
connection point for reassembly.

10. With the 1/2” wrench remove the X1
secondary lead from the polarity
switch. See wiring diagram. Label
lead and connection point for
reassembly.

11. With the 1/2” wrench remove the
four nuts and lock washers from the
transformer mounting bolts at the
base of the machine.

12. Carefully hoist the transformer/
choke assembly clear of the base.
Clear all leads.

PRECISION TIG 185

TROUBLESHOOTING & REPAIR

F-55 F-55

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MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (Continued)

REPLACEMENT PROCEDURE

1. Position the new transformer/choke
assembly onto the base and mount­ing bolts.

2. Assemble the four nuts and washers
to the mounting bolts on the base of
the machine.

3. Assemble the X1 secondary lead to
the polarity switch.

4. Assemble the choke lead to the
polarity switch.

5. Install the J3 plug into the control
board.

6. Assemble the H1, H2 or H3 lead onto
the input power switch. Insulate and
secure the unused lead (H2 or H3).

7. Assemble the shunt assembly to the
choke lead.

8. Solder leads R209 and U210 to the
main transformer leads. See wiring
diagram. Insulate connections.

9. Solder leads W201 and W204 to the
main transformer leads. See wiring
diagram. Insulate connections.

10. Solder the two 115VAC leads and

leads B231 and B232 to the main
transformer leads. See wiring dia­gram. Insulate connections.

11. Replace any previously removed

cable ties. Clear leads and check
for “shorts” or “grounds”.

12. Perform the SCR Bridge

Assembly Replacement
Procedure.

PRECISION TIG 185

NOTES

F-56 F-56

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PRECISION TIG 185

TROUBLESHOOTING AND REPAIR

F-57 F-57

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RETEST AFTER REPAIR

Should a machine under test be rejected for any reason requiring the removal of any mechanical part that could
affect the machine’s electrical characteristics, or if any electrical components are repaired or replaced, the machine
must be retested.

Input Volts/Hertz Maximum Idle Amps

208/60 2.50 Amps
230/60 3.00 Amps

Stick Mode OCV

AC 70 - 80VAC

DC 55 - 65VDC

TIG Mode OCV

AC 70 - 80VAC

DC 60 - 70VDC

DC TIG Mode 6 Amps @ 12 Volts

DC TIG Mode 200 Amps @ 29 Volts

MAXIMUM ACCEPTABLE OUTPUT VOLTAGE -

AT MINIMUM OUTPUT SETTINGS

MINIMUM ACCEPTABLE OUTPUT VOLTAGE -

AT MAXIMUM OUTPUT SETTINGS

RECOMMENDED METERS FOR MACHINE OUTPUT TESTS

VOLTMETER: AC and DC True RMS Meter - Fluke 8922A or equivalent

AMMETER: Columbia Type AX AC or DC Tong Ammeter

IMPORTANT: IF OTHER TYPE METERS ARE USED RESULTS MAY NOT BE ACCURATE.

INPUT IDLE AMPS

OPEN CIRCUIT VOLTAGES

PRECISION TIG 185

NOTES

F-58 F-58

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PRECISION TIG 185

Section G-1 Section G-1

TABLE OF CONTENTS

- ELECTRICAL DIAGRAMS SECTION -

Electrical Diagrams ...............................................................................................Section G

Wiring Diagram (G4549) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-2

Entire Machine Schematic (G4588) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-3

Control PC Board Schematic (G4550-1B4-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-4

Control PC Board Schematic (G4550-1B4-2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-5

Control PC Board Schematic (G4550-1B4-3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-6

Control PC Board Assembly (G4551-1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-7

ELECTRICAL DIAGRAMS

G-2

PRECISION TIG 185

WIRING DIAGRAM - ENTIRE MACHINE - (G4549)

G-2

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The wiring diagram specific to your code is pasted inside one of the enclosure panels of your machine.

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VOLTAGE RECONNECTION

SEE RATING PLATE FOR SPECIFIC VOLTAGES

230

or 400-415

(AS SHOWN & AS SHIPPED FROM FACTORY)

or 380

208

C1 AND C2 MUST ALWAYS BE CONNECTED
ACROSS TRANSFORMER PRIMARIES

C2

C1

or 575

VOLT CONNEC

H1 and H3 (HIGH) TO POWER SWITCH.
H2 NOT CONNECTED; INSULATE.

or 460 VOLT C

ONNEC

H1 and H2 (LOW) TO POWER SWITCH.
H3 NOT CONNECTED; INSULATE.

TIO

N

TIO

N

380V AND ABOVE

G

CONNECT GREEN LEAD TO GROUND PER
NATIONAL AND LOCAL ELEC TRICAL CODE

B

CONNECT BLACK AND WHITE LEADS

(L1)

TO SUPPLY CIRCUIT

W

(L2)

208V/230VONLY

TO GROUND PER

NATIONAL ELECTRIC CODE

10K A-B

AT MINIMUM

OPTIONAL

REMOTE

AMPTROL

WORK

ELECTRODE

TM

A
B
C
D
E
F

REMOTE

RECEPTACLE

AC

POS

8

2

4

A
B
C
D
E

4

2

C

FRONT
GANG

0

D

E

POLARITY

SWITCH

INPUTPLUG (208V/2

W

(L2)

B

(L1)

G

S1

POWER

SWITCH

L5

POLARITY SWITCH MICRO SWITCH
A-C, D-E, B-F

AC

B-D, C-E, A-F, G-H

DC+

B-D, A-E, C-F, G-H

DC-

REAR GANG

H

A

F

B

X

S2

DC

1

(REAR VIEW,

SHOWN IN AC POSITION)

285

G

OPEN
CLOSED
CLOSED

MICRO-SWITCH

S2A

NO

NC

312A

311A

S4

CHOKE

H3
H2

H1

313

314

1

4

A

2

5

3

3

2

2

6

0

3

6

2

2

12

3

4

1

2

J4

BALANCE

312

311

PULSE

FREQ

LED

1

A

2

C

3

B

J5

4

D

5
6

E

1

4

6

3

2

210

1
2

0

5

4

4

2

2

11

10

313

204

2
1

201

3

209

314

4

89

3

2

5

1

6

7

J3

AUTO

LED

AC
BALANCE
CONTROL

PULSE

CONTROL

G

POSTFLOW

CONTROL

G

MODE

SWITCH

TIG LED

THERMAL

LED

OUTPUT

CONTROL

DIGITAL
DISPLAY

CONTROL PC BOARD

Y

0
2
2

2

4

G

G

678

J2

RG

STICK LED

285

7

1

3

1

G

G

2

8

6

1

1

2

2

236

1

2345

R3

236A

C4

1

W 221

J1

2

R 222

L4

1

2

J6

3

4

231A

237

115VAC

T2

TRIGGER

POWER

H3 (HIGH)

H2 (LOW)

201

204
209

210

H1

X3

18VAC

X4
X5

18VAC

X6
X1

78VAC

X2

232

X8

115VAC

231

X7

T1

L1

L2

L3

239

238

SPARK

GAP

ARC

STARTER

AS'BLY

284

C3

T3

BYPASS/

STABILIZER

PC BOARD

284A

R2

285A

C1,C2 BY- PASS CAPACITORS, .0047/250VAC
C3 HIGH VOLTAGE CAPACITOR, .0025/10kV
C4 PHASE SHIFT CAPACITOR, 15/250VAC
C5,C6 BY- PASS CAPACITORS, .22/400VDC
CB1CIRCUIT BREAKER, 10A
D1 FREE WHEELING DIODE

284B

L1 OUTPUT INDUCTOR (CHOKE )
L2,L3HIGH FREQUENCY INDUCTORS

R1

L4,L5 RF TOROID CHOKE S
R1,R2 HOLDING RES ISTORS, 100/1 00W

285B

R3 PHASE SHIFT RESISTOR, 200/100W
R4,R5 MICRO START RESISTORS, 12/100W
S1 INPUT POWER SWITCH
S2 POLARITY SW ITCH
S2A MICROSWITCH ON POLARITY SWITCH

S4 MAIN CHOKE THERMOSTAT
SCR1,2,3,4 MAIN POWER SCR'S
SV1 GAS SOLENOID VALVE, 115VAC
T1 M AIN TRANSFORMER
T2 HIG H VO LTAGE TRANSFORMER
T3 HIG H FREQUENCY TRANSFORMER

P7

123

4

J7

2

1

3

4

G

G

G

G

G1

217

G2

G3

216

216A

G4

SHUNT

W 221
R 222

POS

220

220A

SCR1

SCR2

8

1

2

218A

( )

+

SCR3

X2

SCR4

_

( )

D1

DC

LEAD COLORING CODE:

B-BLACK R-RED
G-GREEN W-WHITE

CONNECTOR PIN NUMBERS:

123 7

8

VIEW OF CONNECTOR ON PC BOARD

ELECTRICAL SYMBOLS PER E1537.

30V ONLY

245

244

R4

220A

218A

AC

115VAC

J4

)

R5

260

231A

FAN

COMPONENT VALUE

UNITS:

RESISTORS:

CAPACITORS:

EXAMPLE: THIS IS PIN 7
OF CONNECTOR J4

14

LATCH

231

GAS VALVE

235

SV1

OHMS/WATTS

MFD/VOLTS

G4549

B

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ELECTRICAL DIAGRAMS

G-3

PRECISION TIG 185

SCHEMATIC - ENTIRE MACHINE - (G4588)

G-3

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.

G4588

ENGINEERING CONTROLLED
MANUFACTURER:

POWER-UP SEQUENCE
METER AND M OD E DI S PL A Y TH E P RE VI O U S OUT P UT

CONTROL AND MODE SETTINGS. FAN RUNS FOR 5
SECONDS. IF MODE IS TIG, GAS FLOWS FOR A TIME
SET BY THE POSTFLOW KNOB. OUTPUT IS HOT IF
MODE IS STICK. IN TIG MODE OUTPUT IS COLD UNTIL
TRIGGER IS CLOSED

TYPICAL OC V

65V IN DC
75V IN AC

METER, EN C O D ER, SWITCH, LEDs,
AND ALL POTENTIOMETER S A RE
MOUNTED ON PC BOARD

BALANCE CONTROL IS
DISABLED IN STICK AND
DC TIG

PULSE FREQUENCY IS
DISABLED IN STICK

AUTO LOCAL/REMOTE
STICK MODE: ALWAYS LOCAL
TIG MODE: REMOTE IF PLUGGED
LOCAL IF UNPLUGGED

RECEPTACLE

Left front

U

A

10K

OPTIONAL AMPTROL REMOTE
CONTROL AND ARC START SWITCH

N

B

R

C

B

D

W

E

F

TOROID

TM

HI-FREQ BYPASS CONNECTION
FROM BOTTOM L EFT
MOUNTING H OL E T O SH E ET
METAL

EN-170

CHANGE DETAIL:

No

OUTPUT CONTROL &
MODE SETTINGS ARE
MEMORIZED AT POWER

- DOWN AND RECALLED
AT POWER - UP

OUTPUT CONTROL

(ENCODER)

5 - 185A IN DC
7 - 185A IN AC

MAX. PENET R ATI ON

BALANCE

MAX. CLEA NI N G

AUTO

20 HZ

PULSE FREQUENCY

0.1 HZ

POSTFLOW

LED 1
STICK
(RED)

NEXT TO MODE SWITCH

LED 4

AUT0BALANCE

(GREEN)

NEXT TO BALANCE POT.

OFF IN STICK AND DC TIG

DET_REM

REM_SENSE

AUTO
LOCAL/
REMOTE
CONTROL

RF
CHOKES

1J5

3J5
2J5
5J5
6J5

HI-FREQ BYPASS
CONNECTION

RELEASED FROM X A.02

S1

MODE

+5Vref

OFF

30 S

1 S

REM_POT
TO MICRO
PROCESSSOR

DISPLAY PRESET AT IDLE

ACTUAL AMP WHEN WELDING

NO HOLD FUNCTION

3 DIGIT
METER

(DISP1)

+5V

METER

INTERFACE

+15V

TOGGLE BETWEEN TIG &
STICK.
HI-FREQ, GAS, BALANCE
CONTROL, PULSE
FREQUENCY, &
MICRO-START CIRCUIT
ARE DISABLED IN STICK

A

C

B

A1

+5Vref

From Auto Loc/Rem

CWR1CW

10K

+5Vref

CWR2CW

10K

+5Vref

CWR3CW

10K

NEXT TO MODE SWITCH

FREQUENCY

(GREEN)

NEXT TO PULSE
FREQUENCY POT.

OFF IN STICK, BLINKS AT
FREQUENCY RATE

+15V

-15V

4 PIN (WHITE)
PROGRAMMING
CONNECTOR

J6

+5Vref

(GREEN)

POSTFLOW

+5Vref

PHASE_FIRE
Iarc

SETPOINT

DET_REM

REM_POT

Polling signal
Hi = Local
Remote control

REM_SENSE

DATA

SCLK
XRES

LED 2
THERMAL
(YELLOW)

NEXT TO METER

SOFTWARE

FREQUENCY

6 PIN

PHASE

TRIGGER

TRIGGER
TO MICRO
PROCESSOR

MICRO-

TIG

J1

PROCESSOR

+5V

TRIGGER
INTERFACE

2 PIN

MICRO-PROCESSOR

X1

+5V

LED INTERFACE

LED 3

(GREEN)

LED 5

OUTPUT CONTROL

VERSION LABEL

J5

CONTROL PCB MAIN COMPONENT & DIANOSTIC LED LAYOUT

(VIEWED FROM COMPONENT SIDE)

+24V

+5V

SCR

PHASE

MICRO-START

CIRCUIT

-15V

+5Vref

+24V

INTERFACE

INTERFACE

+5Vref

+24V

+5Vref

115V CIRCUIT

DRIVER

TO MICRO PROCESSOR
AND SCR GATING

+5V

J2

8 PIN

J3

12 PIN

J4

4 PIN

SCHEMATIC G4550­ASSEMBLY G4551-

PHASE

PHASE
DETECTOR

LED 6
THERMAL
(YELLOW)

NEXT TO METER

TWO THERMAL LEDs TO
LIGHT THROUGH
BACK-LIT THERMAL
SYMBOL

POWER SUPPLY

CONTROL PC BOARD

11J3
10J3

9J3

12J3

4J4

1J4
3J4
2J4

5J2
6J2
3J2
8J2
2J2
1J2
4J2
7J2

1J1

2J1

5J3

6J3

2J3

1J3

1J6
2J6

3J6
4J6

4J3
3J3

7J3
8J3

SCR1 GATE
SCR2 GATE
SCR3 GATE
SCR4 GATE

SCR3,SCR2 CATHODE

SCR1 CATHODE

SCR4 CATHODE

SCR1,SCR4 ANODE

BACKGROUND AC INPUT
BACKGROUND ( - )
BACKGROUND ( + )
BACKGROUND AC INPUT

TOROID

SHUNT (+)
SHUNT (-)

CURRENT FEEDBACK

DETERMINE IF HI-FREQ IS
CONTINUOUS OR START
ONLY, MIN. CURRENT, AND
BALANCE CONTROL

MICRO SWITCH INPUT

THERMOSTAT INPUT

DISABLE OUTPUT & HI-FREQ
IF THERMOSTAT OPEN

PROGRAMMING CON N E CT OR
FOR SOFTWA R E U PG R A DE

HI-FREQ (115VAC)
GAS (115VAC)

115VAC IN

FAN (115VAC)

DO NOT REVERSE LEADS
209 & 210, USED FOR SCR
PHASE TIMING

209

18VAC

CONTROL BOARD SUPPLY

210

201

18VAC

TRIGGER CIRCUIT

204

AUX. WINDINGS OF

MAIN TRANSFORMER T1

Front Panel Top

G1
G2
G3
G4

218
217
216
220

216A
245
244
240

W 221

R 222

Left side of Machine

near front

236

235

232

260

X5
X6

T1

X3

X4

216

G4

4

G3

Rear of machine attached to

base, below fan

R4

12/100 EACH

R5

BACKGROUND RESISTORS

TWISTED PAIRS

311

312

314
313

(NORMALLY CLOSED

OPEN AT 135C TYP.)

In Front of main

transformer,

Attached to Base

HIGH
TRANSFORMER

200/100

R3

237

236B

C4

15/250

5.5 OHMS
TYP.

115V

231A

Rear Panel

Right Side

GAS

SOLENOID

(115VAC)

SV1

235

232

220A

IN-LINE CON N ECTOR J7

Inside sleeving at top left side of

Main Rectifier

CHOKE TSTAT

VOLTAGE

T2

S

14.5 KOHMS
TYP.

5000V

F

HI-FREQ CIRCUIT

231

218A

Inside hi-freq box on
right side of machine

L2

12.5 OHM TYP.

12.5 OHM TYP.

L3

3

G2

2

220

1

G1

217
218

On top of Main

Transformer

Lower left side of

Polarity Switch

near front

ARC STARTER ASSEMBLY

238

239

SPARK
GAP .020

435 OHMS TYP.

115VAC

12 OHMS TYP.

260

Right front side of
Main Transformer

COMPONENT LOCATION DESCRIPTIONS ARE AS VIEWED

FROM FRONT OF MACHINE UNLESS STATED

OTHERWISE

FAN

FIRE_SCR

BG

AC/DC

THERMOSTAT

+15V

(GREEN)

+15V

GATING & SNUBBER

+15V

(DISABLED IN STICK)

+15V

OUTPUT REGULATOR

+15V

TRIAC & OPTO-TRIAC

+24V
+15V

+5V

+5Vref

-15V

MODE

+5V

(GREEN)

BALANCE

216A

G4
G3
G2

FREE WHE ELI N G DIO D E

G1

DC

D1

R 222(-)

W 221(+)

OUTPUT

INDUCTOR

SCR4

SCR1

240

311

CLOSED

IN DC

N.C.

OPEN IN AC

HI-FREQ OFF IN STICK
START ONLY IN DC TIG
CONTINUOUS IN AC TIG

312

MICRO SWITCH CLOSED IN DC

C3

12KV

.0015/

HIGH FREQ.

TRANSFORMER

ELECTRODE

Right front

FAN RUNS FOR 5 S AT POWER-UP
STOPS AT IDLE 8 MINUTES
AFTER WELDING.

TYP. RPM:
1600 RPM 60Hz
1340 RPM 50Hz

Between SCR Bridge halves

behind choke.

PROPRIETARY & CONFIDENTIAL:

THE INFORMAT ION ON THIS
PRINT IS FOR REFERENCE
ONLY. COMPONENT S AND
CIRCUITRY MAY BE
FROM AN ACTUAL MACH INE .

MAIN SCR
RECTIFIER

-

SHUNT

400A/200mV

L1

Gang A

CBW

-

DC

T3

AC

284

284A

Top rear
SEE CONNECTION DETAIL

15 - 20 OHM

SCR3

GATE-CATHODE
RESISTANCE TYP.

+

SCR2

Right Side of SCR Bridge
Rectifier. Top of Machine

S

behind Choke.

O
P

Right side of Machine

above Choke Coil.

Gang D

Gang C

Gang B

Gang G

+

CBW

DC

-

DC

CBW

Gang H

AC

CBW

++

DC

CBW

Gang E

BYPASS/STABILIZER

PCB

(SCHEMATIC S22530)

(PCB AS'BLY L10121-1)

100/100

R2

284B

HOLDING RESISTORS

R1

100/100

Mounted to front side
of hi-freq box on
right side of machine
near front.

Center front

WORK

232

DIFFERENT

DC

AC

DC

CBW

CBW

-

DC

CBW

Gang F

285A

285B

Right rear side of Main

Transformer

DESIGN INFORMATION
DRAWN BY:
ENGINEER:

APPROVED:

+

AC

-

CBW

AC

DC

S2

POLARITY SWITCH

Front Panel Center

SEE CONNECTION DETAIL

285

Inside hi-freq box on

right side of machine

Right side of machine,

front of gas solenoid,

attached to Base

THIS DOCUMENT CONTAINS PROPRIETARY INFORMATION OWNED BY LINCOLN GLOBAL, INC. AND MAY NOT BE DUPLICATED, COMMUNICATED
TO OTHER PARTIES OR USED FOR ANY PURPOSE WITHOUT THE EXPRESS WRITTEN PERMISSION OF LINCOLN GLOBAL, INC.

REFERENCE:

Jbarto

Reference

TNguyen

SCALE:

Approve

NONE

X2

80 VAC

X1

CBW = CONNECTED
BY SWITC H
THESE CONNECTIONS
ARE MASE BY POLARITY
SWITCH, THEY ARE NOT
PHYSICAL LEADS

near front

231

T1

X7

115VAC

X8

EQUIPMENT TYPE:
SUBJECT:

MATERIAL
DISPOSITION:

Center of machine

MAIN

TRANSFORMER

T1

H3

H2

H1

SCR
HEATSINK

FARTHEST LEFT
SCR (VIEWED
FROM FRONT)

APPROVAL

UF

DATE:

C1

250VAC

C2

Attached to Power Switch

W

HIGH

LOW

BYPASS ASSEMBLY

.0047/

POWER SWITCH

S1

B

RECONNECT IS DONE AT
POWER SWITCH

Front Panel Left side

VOLTAGE RE CONNE CTION

SEE RATING PLATE FOR SPECIFIC VOLTAGES

230 o

r 400-415 or 575 VOLT CONNECTION

(AS SHOWN & AS SHIPPED FROM FACTORY)

H1 and H3 (HIGH) TO POWER SWITCH.
H2 NOT CONNECTED; INSULATE.

208 o

r 380 or 460 VOLT CONNECTION

H1 and H2 (LOW) TO POWER SWITCH.
H3 NOT CONNECTED; INSULATE.

C1 AND C2 MUST ALWAYS BE CONNECTED

ACROSS TRANSFORMER PRIMAR IES

TO0 COPPER BAR

A

SCR1

1
G

4

8

2

AC

DC-

DC+

8

1

2

SCR2

2
G

7

1

BOTTOM

2

COPPER
BAR

C
A

Gang D

Rear gang H

Gang E

Gang C

POLARITY SWITCH

A-C, D-E, B-F
B-D, C-E, A-F, G-H
B-D, A-E, C-F, G-H

8

1

2

( )

+

G3

S
O

216

P

6 GA. FLEX LEADS

DC

Gang F

MOUNTING HOLE

SCR3

A

A

2

6

6

X

1

1

2

2

Gang A

Rear gang G

gang B

A

0

0

2

2

2

2

240

S
O
P

SCR BRIDGE AND POLARITY SWITCH CONNECTION DETAIL

LEAD COLOR CODE:

B-BLACK O R GR A Y
G-GREEN
O-ORANGE
R-RED OR PIN K
U-BLUE
W-WHITE
Y-YELLOW

LABELS:

COMMON
FRAME GRO UN D

EARTH GROUND

Precision Tig 185

MACHINE SCHEMATIC

PROJECT
NUMBER:

CRM36191

02/20/2004

SCR4

G4

FARTHEST RIGHT SCR
(VIEWED FROM
FRONT)

OUTPUT INDUCTOR

285

MICRO SWITCH

X1

MICRO SW ITC H

OPEN

CLOSED

CLOSED

DOCUMENT
NUMBER:

T
N
U
H
S

D1

( )

_

UNUSED TERMINAL

311

312

GANG LOCATIONS ARE
VIEWED FROM REAR OF
SWITCH

COMPONENT VALUE UNITS:

CAPACITOR: MFD/VOLTS
RESISTOR: OHMS/W ATTS

CONNECTOR PIN NUMBERS:

EX. 12 PIN CONNECTOR

1

712

VIEW OF CONNECTOR ON PC BOARD

PAGE ___ OF ___

G4588

G

W 222
R 222R 222

ALUMINUM BAR

C
D

7 GA. FLEX LEAD

2

1

L1

LATCH

L2

6

1

DOCUMENT
REVISION:

A

INPUT PLUG

E
G
D
E
ID

L
O

S

ELECTRICAL DIAGRAMS

G-4

PRECISION TIG 185

SCHEMATIC - CONTROL PC BOARD - (G4550-1B4-1)

G-4

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual.

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