Lincoln Electric SVM186-A User Manual

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®

PRECISION TIG 225

SVM186-A

October, 2008

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.

For use with machine code numbers:

11317, 11318, 11319
(11320 Ready-Pak)
(11321 Ready-Pak w/Cart)

View Safety Info View Safety Info View Safety Info View Safety Info

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Cleveland, Ohio 44117-1199 U.S.A. TEL: 1.888.935-3877 FAX: [phone] WEB SITE: www.lincolnelectric.com

SERVICE MANUAL

Copyright © Lincoln Global Inc.

• World's Leader in Welding and Cutting Products •

• Sales and Service through Subsidiaries and Distributors Worldwide •

i i

SAFETY

WARNING

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 Above For Diesel Engines

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. A Free 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.

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 Gasoline Engines

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.d. Keep all equipment safety guards, covers and devices in posi-

tion
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
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.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.

and in good repair.Keep hands, hair, clothing and tools

to perform required maintenance. Remove

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

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.

___________________________________________________

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.

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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.

Mar ‘95

ii ii

SAFETY

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.

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.

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. The operation of welding fume control equipment is affected
by various factors including proper use and positioning of the
equipment, maintenance of the equipment and the specific
welding procedure and application involved. Worker expo­sure level should be checked upon installation and periodi­cally thereafter to be certain it is within applicable OSHA PEL
and ACGIH TLV limits.

5.c.

Do not weld in locations near chlorinated hydrocarbon
coming from degreasing, cleaning or spraying operations.
The heat and rays of the arc can react with solvent vapors
form phosgene, a highly toxic gas, and other irritating prod­ucts.

5.d. Shielding gases used for arc welding can displace air and

cause injury or death. Always use enough ventilation,
especially in confined areas, to insure breathing air is safe.

vapors

to

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5.e. 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.

Aug ‘06

iii iii

SAFETY

WELDING and CUTTING
SPARKS can
cause fire or explosion.

6.a.

Remove fire hazards from the welding area.

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
been “cleaned”. For information, purchase “Recommended
Safe Practices for the
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.

Sparks and spatter are thrown from the welding arc. Wear oil

6.f.
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.

If this is not possible, cover them to prevent

though

they have

Preparation

for Welding and Cutting of

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.

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.

6.I. Read and follow NFPA 51B “ Standard for Fire Prevention
During Welding, Cutting and Other Hot Work”, available from
NFPA, 1 Batterymarch Park,PO box 9101, Quincy, Ma
022690-9101.

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

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Jan ‘07

iv iv

SAFETY

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 LʼArc

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.

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.

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.

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.

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Mar ‘93

v v

SAFETY

Electromagnetic Compatibility (EMC)

Conformance
Products displaying the CE mark are in conformity with European Community Council Directive of 3 May
1989 on the approximation of the laws of the Member States relating to electromagnetic compatibility
(89/336/EEC). It was manufactured in conformity with a national standard that implements a harmonized
standard: EN 60974-10 Electromagnetic Compatibility (EMC) Product Standard for Arc Welding Equipment.
It is for use with other Lincoln Electric equipment. It is designed for industrial and professional use.

Introduction
All electrical equipment generates small amounts of electromagnetic emission. Electrical emission may be
transmitted through power lines or radiated through space, similar to a radio transmitter. When emissions
are received by other equipment, electrical interference may result. Electrical emissions may affect many
kinds of electrical equipment; other nearby welding equipment, radio and TV reception, numerical controlled
machines, telephone systems, computers, etc. Be aware that interference may result and extra precautions
may be required when a welding power source is used in a domestic establishment.

Installation and Use
The user is responsible for installing and using the welding equipment according to the manufacturer’s
instructions. If electromagnetic disturbances are detected then it shall be the responsibility of the user of the
welding equipment to resolve the situation with the technical assistance of the manufacturer. In some cases
this remedial action may be as simple as earthing (grounding) the welding circuit, see Note. In other cases
it could involve construction of an electromagnetic screen enclosing the power source and the work com­plete with associated input filters. In all cases electromagnetic disturbances must be reduced to the point
where they are no longer troublesome.

Note: The welding circuit may or may not be earthed for safety reasons according to national

codes. Changing the earthing arrangements should only be authorized by a person who is
competent to access whether the changes will increase the risk of injury, e.g., by allowing
parallel welding current return paths which may damage the earth circuits of other equip­ment.

Assessment of Area
Before installing welding equipment the user shall make an assessment of potential electromagnetic prob­lems in the surrounding area. The following shall be taken into account:

a) other supply cables, control cables, signaling and telephone cables; above, below and adjacent to the

welding equipment;

b) radio and television transmitters and receivers;

c) computer and other control equipment;

d) safety critical equipment, e.g., guarding of industrial equipment;

e) the health of the people around, e.g., the use of pacemakers and hearing aids;

f) equipment used for calibration or measurement

g) the immunity of other equipment in the environment. The user shall ensure that other equipment being

used in the environment is compatible. This may require additional protection measures;

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h) the time of day that welding or other activities are to be carried out.

L10093 3-1-96H

vi vi

SAFETY

Electromagnetic Compatibility (EMC)

The size of the surrounding area to be considered will depend on the structure of the building and other
activities that are taking place. The surrounding area may extend beyond the boundaries of the premises.

Methods of Reducing Emissions

Mains Supply
Welding equipment should be connected to the mains supply according to the manufacturer’s recommen­dations. If interference occurs, it may be necessary to take additional precautions such as filtering of the
mains supply. Consideration should be given to shielding the supply cable of permanently installed welding
equipment, in metallic conduit or equivalent. Shielding should be electrically continuous throughout its
length. The shielding should be connected to the welding power source so that good electrical contact is
maintained between the conduit and the welding power source enclosure.

Maintenance of the Welding Equipment
The welding equipment should be routinely maintained according to the manufacturer’s recommendations.
All access and service doors and covers should be closed and properly fastened when the welding equip­ment is in operation. The welding equipment should not be modified in any way except for those changes
and adjustments covered in the manufacturers instructions. In particular, the spark gaps of arc striking and
stabilizing devices should be adjusted and maintained according to the manufacturer’s recommendations.

Welding Cables
The welding cables should be kept as short as possible and should be positioned close together, running at
or close to floor level.

Equipotential Bonding
Bonding of all metallic components in the welding installation and adjacent to it should be considered.
However, metallic components bonded to the work piece will increase the risk that the operator could
receive a shock by touching these metallic components and the electrode at the same time. The operator
should be insulated from all such bonded metallic components.

Earthing of the Workpiece
Where the workpiece is not bonded to earth for electrical safety, not connected to earth because of its size
and position, e.g., ships hull or building steelwork, a connection bonding the workpiece to earth may reduce
emissions in some, but not all instances. Care should be taken to prevent the earthing of the workpiece
increasing the risk of injury to users, or damage to other electrical equipment. Where necessary, the con­nection of the workpiece to earth should be made by a direct connection to the workpiece, but in some
countries where direct connection is not permitted, the bonding should be achieved by suitable capaci­tance, selected according to national regulations.

Screening and Shielding
Selective screening and shielding of other cables and equipment in the surrounding area may alleviate
problems of interference. Screening of the entire welding installation may be considered for special applica-

1

tions.

_________________________

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1

Portions of the preceding text are contained in EN 60974-10: “Electromagnetic Compatibility (EMC)
product standard for arc welding equipment.”

L10093 3-1-96H

I I

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- MASTER TABLE OF CONTENTS FOR ALL SECTIONS -

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Page

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

Installation..................................................................SectionA

Operation ..................................................................SectionB

Accessories ................................................................SectionC

Maintenance ................................................................SectionD

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

TroubleshootingandRepair ...................................................SectionF

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

Parts Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .P-536, P-210-R, P-66-J.6

PRECISION TIG® 225

A-1 A-1

Installation.............................................................................A-1

TechnicalSpecifications.............................................................A-2,A-3

SafetyPrecautions ....................................................................A-4

Select Suitable Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-4

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

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

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

LiftingandMoving ....................................................................A-4

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

TABLE OF CONTENTS - INSTALLATION SECTION

Machine Grounding and High Frequency Interference Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-5

Input and Grounding Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-5

InputReconnectProcedure .............................................................A-6

OutputConnections ...................................................................A-6

ConnectionsForTig(GTAW)Welding .....................................................A-7

Tig Torch Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-7

Work Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-7

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

RemoteControlConnection .............................................................A-7

Connections For Stick (SMAW) Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-7

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

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PRECISION TIG® 225

A-2 A-2

INSTALLATION

TECHNICAL SPECIFICATIONS - PRECISION TIG® 225 (K2533-1AND K2535-1,-2)

INPUT - SINGLE PHASE ONLY

Standard Voltage

Input Current at Rated Output

Power Factor

Idle Current

208/230/1/60

42A / 39A Effective

0.62 Min.

and 94A / 85A Maximum

OUTPUT RANGE

Output Current

Range

5-230 Amps (AC)
5-230 Amps (DC)

Maximum Open

Circuit Voltage

(STICK AND TIG)

AC OCV: 75
DC OCV: 66

CC (Constant Current)

RATED OUTPUT

Process Duty Cycle**

Weld Current*

GTAW

10% Duty Cycle

20% Duty Cycle

100% Duty Cycle

225A AC/DC
180A AC/DC

90A AC/DC (BAL.)

80A AC (AUTO-BAL.)

SMAW
10% Duty Cycle
20% Duty Cycle

100% Duty Cycle

225A AC/DC
180A AC/DC

90A AC/DC

**Chart gives max. rated Output Amps @% Duty Cycle (Based on a 10 minute cycle).

(Example; 180A@20% for AC/DC Stick and TIG)

* Inputs and ratings include a 20 amp rated load on the 115vac receptacle.

AC/DC Stick and Auto-Balance TIG Output Limits

2

Using provided input cable for protected

input supply

1

Weld Voltage (NEMA)

3.0A/2.7A Max.

Type of Output

AC/DC

15.7 V AC/DC

15.2 V AC/DC

14.1 V AC/DC

14.0 V AC/DC

29.0 V AC/DC

27.2 V AC/DC

23.4 V AC/DC

100%

90%

80%

70%

AC/DC Stick & Bal.TIG

60%

50%

40%

30%

Output Duty Cycle

with Max. Aux. load or
Auto-B al. TIG w/o Aux.

AC Auto -B al. T IG w ith
Max. Aux. L oad

20%

10%

0%

50 70 90 110 130 150 170 190 210 230

1

Output Limits allow for continuous max. rated load on 115vac auxiliary receptacle.

2

Wiring and protection based on the 2005 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.

Output Amps

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PRECISION TIG® 225

A-3 A-3

INSTALLATION

TECHNICAL SPECIFICATIONS - CANADIAN (K2533-2), INTERNATIONAL K2534-1)

K2533-2 INPUT (at Rated Output)

Voltage/Phase/Freq.

460/575/1/60

Voltage/Phase/Freq.

380/400-415/1/50/60

N80

Max. OCV.

75 V (AC)
66 V (DC)

Process Duty Cycle**

SMAW

15%
20%

100%

Current

18 A/15 A Effective

42 A/33 A Max.

Power Factor

0.62 Min.

K2534-1 INPUT (at Rated Output)

Current

21 A/20 A Effective

50 A/48 A Max.

Power Factor

0.62 Min.

OUTPUT RANGE

Weld Current

5-230 A (AC)
5-230 A (DC)

RATED OUTPUT

Weld Current*

225 A AC/DC

180 A AC/DC

90 A AC/DC

Idle Current

1.3 A/1.0 A Max.

Idle Current

1.5 A/1.4 A Max.

Output Type

CC (Constant Current)

AC or DC

Weld Voltage (NEMA)

29.0 V

27.2 V

23.4 V

GTAW

10%
20%

100%

225 A AC/DC

180 A AC/DC

90 A AC/DC (Bal.)

80 A AC (Auto-Bal.)

* Inputs and ratings include a 6 amp rated load on the 115vac receptacle.
** Based on a 10 minute cycle.

PHYSICAL DIMENSIONS

MODEL HEIGHT WIDTH DEPTH WEIGHT

Machine Only

(K2533-1,-2)

(K2534-1)

Ready-Pak

(K2535-1)

Ready-PakW/Cart

(K2535-2)

(2)

Dimensions are without Lift Eyebolt and Torch Holder

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

ENVIRONMENTAL RANGES

Operating Temperature -4°F to 104°F (-20°C to 40°C)
Storage Temperature -40°F to 185°F (-40°C to 85°C)

(2)

25.62 in.
751 mm

25.62 in.
651 mm

38.01 in.
966 mm

15.7 V

15.2 V

14.1 V

14.0 v

Approx. 192 lbs.

87.1 kgs

Approx. 212lbs..

96.2 kgs.

Approx. 258lbs.

117.0 kgs.

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PRECISION TIG® 225

A-4 A-4

SAFETY PRECAUTIONS

Read entire installation section before starting
installation.

WARNING

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 PRECISION TIG® 225 to a
power supply grounded per the National Electrical
Code and any local codes.

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

SELECT SUITABLE LOCATION
MOUNTING

INSTALLATION

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 unit.
Refer to the Accessories section of this manual.

WARNING

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® 225.

Environmental Rating

The PRECISION TIG® 225 power source carries an
IP21S 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.

• The PRECISION TIG® 225 must be located where
there is free circulation of clean air such that air
movement in and out the back air vents will not be
restricted.

• Dirt and dust that can be drawn into the PRECISION
TIG® 225 should be kept to a minimum. Failure to
observe these precautions can result in excessive
operating temperatures and nuisance shutdown.

GRINDING

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

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.

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STACKING

PRECISION TIG® 225 cannot

be stacked.

LIFTING AND MOVING

The PRECISION TIG® 225 models are provided with
an Eyebolt used for lifting the unit with a hoist.

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PRECISION TIG® 225

A-5 A-5

MACHINE GROUNDING AND HIGH FRE­QUENCY INTERFERENCE PROTECTION

Locate the Precision TIG® 225 away from radio controlled
machinery. The normal operation of the Precision TIG®
225 may adversely affect the operation of RF controlled
equipment, which may result in bodily injury or damage to
the equipment.

INSTALLATION

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 covers and all screws securely in place.

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

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.

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 AND GROUNDING CONNECTIONS

Only a qualified electrician should connect the PRECI­SION TIG® 225. Installation should be made in accor­dance with the appropriate National Electrical Code, all

local codes and the information in this manual.

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 #6-3 input power cord and a NEMA 6 -50R receptacle
is included with the Ready-Pak™ models. Other voltage
models have an #12-3 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 begin-
ning of this section. Fuse the input circuit with the recom­mended super lag fuses or delay type
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.

1

circuit breakers.

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PRECISION TIG® 225

A-6 A-6

FIGURE A.1 Reconnect Leads

INPUT LEADSINPUT LEADS

L1 & L2L1 & L2

LEAD H1LEAD H1

(DO NOT(DO NOT
REMOVE)REMOVE)

FOR LOWEST RATED VOLTAGEFOR LOWEST RATED VOLTAGE

: H2 CONNECTED : H2 CONNECTED

FOR HIGHEST RATED VOLTAGEFOR HIGHEST RATED VOLTAGE

: H3 CONNECTED : H3 CONNECTED

BACK VIEW OF LINE SWITCHBACK VIEW OF LINE SWITCH

INSTALLATION

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.

CAUTION

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

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

Multiple voltage models are shipped connected for
the highest voltage. To change this connection
refer to the following instructions.

WARNING

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.

OUTPUT CONNECTIONS

ELECTRODE/GAS

OUTLET
RECEPTACLE
(TWIST-MATE)

WORK CABLE & CLAMP

FIGURE A.2 Location of Output Connections

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

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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® 225.

PRECISION TIG® 225

A-7 A-7

CONNECTIONS FOR TIG (GTAW) WELDING

TIG TORCH CONNECTION

INSTALLATION

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

A PTA-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

WARNING

A work cable with attached work clamp is factory con­nected to the PRECISION TIG® 225. To minimize high
frequency interference, refer to Input and Ground
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® 225
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.

WARNING

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® 225
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 the Accessories
Section of this manual for STICK welding equipment

which is available for use with the PRECISION TIG®

225. An electrode holder with Twist-Mate™ cable and
Twist-Mate™ connector are available separately for
use with the PRECISION TIG® 225. (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.

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PRECISION TIG® 225

A-8 A-8

NOTES

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PRECISION TIG® 225

B-1 B-1

Operation..............................................................................B-1

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

GraphicSymbols .....................................................................B-2

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

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

RecommendedProcesses ..............................................................B-3

ProcessLimitations ...................................................................B-3

Recommended Equipment/Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-3

EquipmentLimitation ..................................................................B-3

TABLE OF CONTENTS - OPERATION SECTION

WeldingCapability ....................................................................B-3

Controls and Settings . . . . . . . . . . . . . . . . . . . . ..........................................B-4,B-5

Power-Up Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-5

CaseRearComponents................................................................B-6

OperatingSteps ......................................................................B-7

WeldinginTIGMode ..................................................................B-7

PulseTIGMode ......................................................................B-7

RemoteControlOperation ..............................................................B-8

Benefits of the PRECISION TIG® 225 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .B-8

WeldinginStickMode .................................................................B-9

Recommended Electrode Amperage Ranges ...............................................B-9

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PRECISION TIG® 225

B-2 B-2

T

SAFETY PRECAUTIONS

OPERATION

GRAPHIC SYMBOLS THAT APPEAR ON

HIS MACHINE OR IN THIS MANUAL

Read and understand this entire section before operat­ing the machine.

INPUT POWER

WARNING

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.

POSITIVE OUTPUT

NEGATIVE OUTPUT

DIRECT CURRENT

PROTECTIVE
GROUND

WARNING OR
CAUTION

DO NOT SWITCH
WHILE WELDING

SINGLE PHASE
TRANSFORMER AC AND
RECTIFIER DC POWER
SOURCE

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

• Wear eye, ear and body
protection.

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

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

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

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OFF

ON

PRECISION TIG® 225

B-3 B-3

PRODUCT DESCRIPTION

OPERATION

PROCESS LIMITATIONS

The PRECISION TIG® 225 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 Micro-Start II™
Technology for its lower Minimum(5 amps) to higher
Maximum (230 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.) A new undercarriage
(with gas bottle rack) is available for field installation, or is
included with an available Ready-Pak TIG Welding
Package. The PRECISION TIG® patented convenient
built-in storage provisions for welding components and
cable management.

The PRECISION TIG® 225 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 shielding

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.

An Auxiliary 115vac Receptacle with Circuit Breaker are
included on the back panel of the PRECISION TIG® 225
models. The Canadian (K2533-2) and International (K2534-

1) models are rated 6 amps, while the 208/230/1/60 models

(K2533-1 and K2535-1/-2) are rated 20 amps (for use with
Lincoln’s 115v SP and Power MIG models).

RECOMMENDED PROCESSES AND EQUIP­MENT

RECOMMENDED PROCESSES

The PRECISION TIG® machines are not recommended for
arc gouging due to its 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® 225 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 with Domestic, Canadian
and International input voltages for user configuration, with
optional accessories.

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

Plug Cable and Receptacle (K2533-1)

460/575/1/60 Machine only with cable (K2533-2)
380/400/415/1/50/60 Machine only

with cable (K2534-1)

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® 225 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® 225 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.

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The PRECISION TIG® 225 is recommended for the TIG
(GTAW) and Stick (SMAW) welding processes within its out­put capacity range of 5 amps DC or AC to 225 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.

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WELDING CAPABILITY(Duty Cycle)

The PRECISION TIG® 225 is rated at 225 amps, 29 volts, at
10% 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® 225

B-4 B-4

OPERATION

CONTROLS AND SETTINGS

All operator controls and adjustments are located on the front of the PRECISION TIG 225. Refer to Figure B.1
and corresponding explanations.

FIGURE B.1 - CONTROL PANEL

13

9

5

3

4

8

1

2

1. POWER SWITCH

2. POLARITY SWITCH

3. MODE SWITCH

4. AC BALANCE CONTROL

5. MAXIMUM

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

OUTPUT CONTROL (AMPS)

6

7

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10

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, also
see the following page for Power-Up Sequence).

2. POLARITY SWITCH – The rotary power switch has

3-positions for DC+, AC and DC- selections for the
electrode output stud welding polarity.

CAUTION

• 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 potentiometer

control permits AC TIG wave balance adjustment
from Max. Penetration (~80% negative wave) at full
CW rotation setting, to CCW rotation Max. Cleaning
(~60% positive wave), and includes:

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• Auto Balance position indicated by the Green panel

light turning on. This 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) connect-

ed 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
would not have stopped flowing.

PRECISION TIG® 225

11

12

during Post Flow time, since shielding gas

B-5 B-5

8. PULSE TIG CONTROL – The Pulse TIG feature

built into the PRECISION TIG® 225 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
fixed 50%.

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

9. THERMAL SHUTDOWN LIGHT This Yellow LED

panel light turns on if the machine output is shut­down because internal overheating has occurred,
and turns off when cooled to reset.

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)toStickwill
automatically disable
trol and switch the output control back to the Max
Output panel control.

the connected remote con-

OPERATION

POWER-UP SEQUENCE

When the PRECISION TIG® 225 Power switch is ini­tially turned On , the following will be observed:
(Refer to this Section Controls and Settings Figure
B.1)

• The cooling fan will run for about 5 seconds.

• The previous (prior to Power Off) settings of Mode
and Maximum Output will be initiated.

• If in TIG Mode, the shielding gas solenoid valve will

and dur-

be activated for the time set by the Post Flow Time
control.

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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 10ft.(3.05m) cable with work

clamp is factory connected to the welder and its
clamp 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.

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PRECISION TIG® 225

B-6 B-6

OPERATION

CASE REAR COMPONENTS

FIGURE B.2

4

3

5

2

1. INPUT CABLE– This #6-3 (208/230V) or #12-3

(380V and higher) heavy duty cable with cable
clamp is factory installed on all models. The
Domestic models (208/230V) also are equipped with
a NEMA 6-50P plug.

2. GAS INPUT CONNECTOR – This is a 5/8-18 right-

hand thread female fitting for connection of input gas
supply.

3. COOLING AIR VENTS – Air is drawn in through the

upper vents and exhausted out through the lower
vents. The louver baffle steers exhaust air down and
prevents it from re-entering the upper vents.

4. MACHINE RATING PLATE

5. RECEPTACLE AND CIRCUIT BREAKER-115vac

auxiliary NEMA 6-20R .

1

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PRECISION TIG® 225

B-7 B-7

OPERATION

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.

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• 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.

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PRECISION TIG® 225

B-8 B-8
REMOTE CONTROL OPERATION

OPERATION

BENEFITS OF THE PRECISION TIG® 225 DESIGN

A Foot Amptrol is included with the PRECISION TIG®
225 Ready-Pak models and available 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 (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.

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® 225 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.

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® 225 will start a 3/32”, 2%
thoriated tungsten electrode at 15 amperes provided
the electrode tip is properly grounded and not contam­inated.

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PRECISION TIG® 225

B-9 B-9
WELDING IN STICK MODE

OPERATION

5. Turn the power switch to “ON”.

1. Put the electrode holder and cable quick connect

6. Adjust the Current Control to the desired amps.
plug into the electrode output receptacle. Turn clock­wise until tight. Connect the work clamp to the work

7. Strike an arc and weld.
piece.

NOTE: When the TIG/STICK switch is set to “STICK”

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

the output is always on when the power switch
is on. A remote control has no effect on the

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

welding current and the gas flow and high fre­quency TIG arc starter are disabled.

DC+).

4. Place the electrode in the electrode holder.

WARNING

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

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

RECOMMENDED ELECTRODE AMPERAGE RANGES - PRECISION TIG 225

The PRECISION TIG 225 is rated from 5-225 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 225
Blue Max procedures are based on C6.1 6/95

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

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GTAW Process

Electrode Polarity DC- AC Approximate Argon

Electrode Tip Preparation

Electrode Type

Sharpened Balled Gas Flow Rate

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

EWTh-1, EWCe-2

EWTh-2, EWLa-1

EWP EWCe-2, EWLa-1 Stainless

EWTh-1, EWTh-2

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.

PRECISION TIG® 225

B-10 B-10

NOTES

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PRECISION TIG® 225

C-1 C-1

Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-1

Standard Equipment Packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-2

FactoryInstalledOptions ...............................................................C-3

FieldInstalledOptions .................................................................C-4

TABLE OF CONTENTS - ACCESSORIES SECTION

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PRECISION TIG® 225

C-2 C-2

STANDARD EQUIPMENT PACKAGES

The PRECISION TIG® 225 will be available in two
Factory-Configured Welding Packages:

1. PRECISION TIG® 225 Ready-Pak (K2535-1)

• 208/230/1/60 Machine (K2533-1)

• 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® 225 will also be available as Basic models with Domestic, Canadian and International
input voltages for user-configuration:with optional accessories. (See Table C.1)

ACCESSORIES

2. PRECISION TIG® 225 Ready-Pak w/Cart (K2535-

2)

• 208/230/1/60 Machine (K2533-1)

• 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 K2533-1 Machine Only model.

TABLE C.1

Select Machine

Optional
Torch Starter Kit
(Select one)

Water Cooler Not Applicable K1813-1 115V 50/60Hz Cool-Arc 40

Optional Under­Storage Cart

Optional Remote
Trigger Device
(Select one)

208/230/1/60 Machine with 9 ft.(2.7m) NEMA 6-50P Plug Cable and Receptacle (K2533-1)
460/575/1/60 Machine only with Cable (K2533-2)

380/400-415/1/50-60 Machine only with Cable (K2534-1)

Water Cooled System

K2267-1 TIG-Mate 20 Torch Starter Kit
K1813-1 115V 50/60Hz Cool-Arc 40

K2348-1

K814 Arc Start Switch
K870 Foot Amptrol
K963-3 Hand Amptrol

K2266-1 TIG-Mate Torch Starter

Air Cooled System

Not Applicable

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PRECISION TIG® 225

C-3 C-3

FACTORY INSTALLED OPTIONS

The PRECISION TIG® 225 will be available in two
Factory-Configured Welding Packages:

1. PRECISION TIG® 225 Ready-Pak (K2535-1)

• 208/230/1/60 Machine (K2533-1)

• 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’ Ultra-Flex Torch (K1782-12) Includes:

- 3/32 2%Th Tungsten

- 3/32 Collet (10N24)

- 3/32 Collet Body (10N32)

- #7 Alumina Nozzle (10N47)

• Foot Amptrol (K870)

• TIG Slide Rule ( WC332)*

• GTAW Book (JFLF-834)*

• Lift Eyebolt*

The PRECISION TIG® 225 will also be available as Basic models with Domestic, Canadian and International
input voltages for user-configuration with optional accessories: (See Table C.2)

ACCESSORIES

2. PRECISION TIG® 225 Ready-Pak w/Cart (K2535-

2)

• 208/230/1/60 Machine (K2533-1)

• 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’ Ultra-Flex Torch (K1782-12) Includes:

- 3/32 2%Th Tungsten

- 3/32 Collet (10N24)

- 3/32 Collet Body (10N32)

- #7 Alumina Nozzle (10N47)

• Foot Amptrol (K870)

• TIG Slide Rule (WC332)*

• GTAW Book (JFLF-834)*

• Lift Eyebolt*

• Under-Storage Cart (K2348-1)

* Included with K2533-1 Machine Only model.

Select Machine

Optional
Torch Starter Kit
(Select one)

Water Cooler

Optional Under­Storage Cart

Optional Remote
Trigger Device
(Select one)

TABLE C.2
208/230/1/60 Machine with 9 ft.(2.7m) NEMA 6-50P Plug Cable and Receptacle (K2533-1)
460/575/1/60 Machine only with Cable (K2533-2)

380/400-415/1/50-60 Machine only with Cable (K2534-1)

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

•WaterHose&HoseCoupler

• Work Cable & Clamp (Not required for

PRECISION TIG® 225)

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

K2348-1

K814 Arc Start Switch
K870 Foot Amptrol
K963-3 Hand Amptrol

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® 225)

Not Applicable

Air Cooled System

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PRECISION TIG® 225

C-4 C-4

FIELD INSTALLED OPTIONS

The following Options/Accessories are available for the
PRECISION TIG® 225:

• 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)

ACCESSORIES

• 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.)

• K870 Foot Amptrol

Single pedal foot activation of arc start switch and
output control, with 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® 225)

• K2374-1 Electrode Holder and Cable

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

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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

•WorkCable&Clamp
(Not required for PRECISION TIG® 225)

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PRECISION TIG® 225

D-1 D-1

Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .D-1

SafetyPrecautions ....................................................................D-2

Routine and Periodic Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .D-2

SparkGapAdjustment .................................................................D-2

FanMotororFanBladeReplacement.....................................................D-2

TABLE OF CONTENTS - MAINTENANCE SECTION

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PRECISION TIG® 225

D-2 D-2

.020 Spark Gap

MAINTENANCE

SAFETY PRECAUTIONS

WARNING

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.

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

WARNING

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

•PCBoards

• Fan Blades

WARNING

Use extreme caution when working with a high fre­quency circuit. 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 contami­nant's, 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 decal's.

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

FIGURE D.1 SPARK GAP

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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 .020(.5mm) is set at the factory to a
gap of 0.015 inches (0.4mm) 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).

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.020 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.

.30ł

FIGURE D.2

PRECISION TIG® 225

E-1 E-1

TABLE OF CONTENTS-THEORY OF OPERATION SECTION

TheoryofOperation .....................................................................E-1

GeneralDescription ...................................................................E-2

InputPowerCircuit ....................................................................E-2

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

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

DCWeldingOutput ...................................................................E-5

ACWeldingOutput ...................................................................E-6

SCROperation .......................................................................E-7

ProtectiveCircuits ....................................................................E-8

ThermalProtection ....................................................................E-8

OverloadProtection ...................................................................E-8

FIGURE E.1 PRECISION TIG® 225 BLOCK LOGIC DIAGRAM

BY-PASS

INPUT
POWER
SWITCH

115 VAC
Receptacle

BYPASS
ASBLY

FAN

Circuit Breaker
Protected

MAIN

TRANSFORMER

H1

H2

H3

X1

X2

18VAC

115VAC

18VAC

POLARITY

SWITCH

AC

DC+

SCR

BRIDGE

DC-

AC

SHUNT

CONTROL

BOARD

BOARD

HI-FREQUENCY
TRANSFORMER

C
H
O
K
E

HIGH VOLTAGE
TRANSFORMER

115VAC

CIRCUIT

MODE

SWITCH

POWER

"ON"

DIGITAL
DISPLAY

F
E
E
D
B
A
C
K

WORK

ELECTRODE

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REMOTE

RECEPTACLE

AUTO

BALANCE

LED

TIG
LED

STICK
LED

PULSE
FREQ.

LED

PRECISION TIG® 225

THERMAL

LIGHT

GAS

VALVE

THERMO-

STATS

OUTPUT
CONTROL

BALANCE

AC

CONTROL

PULSE
CONTROL

POSTFLOW
CONTROL

E-2 E-2

THEORY OF OPERATION

FIGURE E.2 - General Description & Input Power Circuit

BY-PASS

INPUT
POWER
SWITCH

BYPASS
ASBLY

115 VAC
Receptacle

FAN

Circuit Breaker
Protected

MAIN

TRANSFORMER

H1

H2

H3

REMOTE

RECEPTACLE

X1

X2

18VAC

115VAC

18VAC

POLARITY

AC

AC

THERMAL

LIGHT

SWITCH

DC+

SCR

BRIDGE

DC-

CONTROL

BOARD

GAS

VALVE

SHUNT

F
E
E

D

B

A

C

K

THERMO-

STATS

BOARD

C
H
O
K
E

OUTPUT
CONTROL

HIGH VOLTAGE

TRANSFORMER

CIRCUIT

115VAC

MODE

SWITCH

HI-FREQUENCY
TRANSFORMER

POWER

"ON"

DIGITAL
DISPLAY

WORK

ELECTRODE

AUTO

BALANCE

LED

PULSE
FREQ.

LED

TIG
LED

STICK
LED

GENERAL DESCRIPTION

The PRECISION TIG® 225 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
Technology for its lower Minimum (5amps) to high-

er Maximum (225 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.)

TM

AC

BALANCE

CONTROL

PULSE
CONTROL

POSTFLOW
CONTROL

INPUT POWER CIRCUIT

The desired single-phase input power is connected to
the TIG 225 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, the 115 VAC
receptacle, 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.

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NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion

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PRECISION TIG® 225

E-3 E-3

THEORY OF OPERATION

FIGURE E.2 - Output Rectification & Feedback Control

BY-PASS

INPUT
POWER
SWITCH

BYPASS
ASBLY

115 VAC
Receptacle

FAN

Circuit Breaker
Protected

MAIN

TRANSFORMER

H1

H2

H3

REMOTE

RECEPTACLE

X1

X2

115VAC

18VAC

18VAC

POLARITY

AC

AC

THERMAL

LIGHT

SWITCH

DC+

SCR

BRIDGE

DC-

CONTROL

BOARD

GAS

VALVE

SHUNT

F
E
E
D
B
A
C
K

THERMO-

STATS

BOARD

C
H
O
K
E

OUTPUT
CONTROL

HIGH VOLTAGE
TRANSFORMER

CIRCUIT

115VAC

MODE

SWITCH

HI-FREQUENCY
TRANSFORMER

POWER

"ON"
DIGITAL
DISPLAY

WORK

ELECTRODE

AUTO

BALANCE

LED

PULSE
FREQ.

LED

TIG
LED

STICK
LED

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.

AC

BALANCE

CONTROL

PULSE
CONTROL

POSTFLOW
CONTROL

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NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion

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PRECISION TIG® 225

E-4 E-4

THEORY OF OPERATION

FIGURE E.2 - High Voltage/High Frequency Circuit.

BY-PASS

INPUT
POWER
SWITCH

115 VAC
Receptacle

BYPASS
ASBLY

FAN

Circuit Breaker
Protected

MAIN

TRANSFORMER

H1

H2

H3

X1

X2

18VAC

115VAC

18VAC

POLARITY

SWITCH

AC

DC+

SCR

BRIDGE

DC-

AC

SHUNT

E
E
D
B
A
C
K

CONTROL

BOARD

BOARD

HI-FREQUENCY
TRANSFORMER

C
H
O
K
E

HIGH VOLTAGE

TRANSFORMER

115VAC

CIRCUIT

MODE

SWITCH

POWER

"ON"

DIGITAL
DISPLAY

F

WORK

ELECTRODE

REMOTE

RECEPTACLE

THERMAL

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.

GAS

THERMO-

OUTPUT

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NOTE: Unshaded areas of Block Logic

Diagram are the subject of discussion

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PRECISION TIG® 225

E-5 E-5

CHOKE

THEORY OF OPERATION

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.

ELECTRODE

PRIMARY

1Ø

G

G

FIGURE E.5 DC Welding Current Generation.

G

G

DC

WORK

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PRECISION TIG® 225

E-6 E-6

THEORY OF OPERATION

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.

CHOKE

G

G

G

G

ELECTRODE

PRIMARY

1Ø

DC

WORK

FIGURE E.6 AC Square Wave Welding Current Generation.

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PRECISION TIG® 225

E-7 E-7

THEORY OF OPERATION

SCR OPERATION

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

ode 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.

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ANODE

CATHODE

GATE

INPUT

OUTPUT

GATE

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

FIGURE E.7 SCR Operation

PRECISION TIG® 225

E-8 E-8

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.

THEORY OF OPERATION

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

THERMAL PROTECTION

The machine is electronically protected from producing

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.

excessively high output currents. The output is limited
to 200 amps.

115 VAC RECEPTACLE

The auxiliary receptacle is circuit breaker protected.
Canadian {K2J33-2} and International {K2J34-1}
modes are 6 amps. K2533-1 and K2535-1/-2
208/230/1/60 modes are rated 20 amps.

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PRECISION TIG® 225

F-1 F-1

TABLE OF CONTENTS - TROUBLESHOOTING AND REPAIR

Troubleshooting and Repair.............................................................................................................................F-1

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-55

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PRECISION TIG® 225

F-2 F-2

TROUBLESHOOTING AND REPAIR

HOW TO USE TROUBLESHOOTING GUIDE

WARNING

Service and Repair should only be performed by Lincoln Electric Factory Trained
Personnel. Unauthorized repairs performed on this equipment may result in danger to
the technician and machine operator and will invalidate your factory warranty. For your
safety and to avoid Electrical Shock, please observe all safety notes and precautions
detailed throughout this manual.

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

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

Step 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 the following
categories: output problems, function prob­lems, wire 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. RECOMMENDED
COURSE OF ACTION

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
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 specified 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.

to eliminate

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CAUTION

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

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

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PRECISION TIG® 225

F-3 F-3

TROUBLESHOOTING AND REPAIR

PC BOARD TROUBLESHOOTING PROCEDURES

WARNING

ELECTRIC SHOCK
can kill.

•

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

CAUTION

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

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

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.

- 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.

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

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

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PRECISION TIG® 225

F-4 F-4

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

Machine is dead. No output - No fan-No115VACatreceptacle.

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

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

4. CB-1 circuit breaker open.

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.

RECOMMENDED

COURSE OF ACTION

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.

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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.

CAUTION

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

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

PRECISION TIG® 225

F-5 F-5

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

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.

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

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.

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CAUTION

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

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

PRECISION TIG® 225

F-6 F-6

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

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.

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

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.

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CAUTION

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

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

PRECISION TIG® 225

F-7 F-7

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

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

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

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.

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.

CAUTION

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.

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

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

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

PRECISION TIG® 225

F-8 F-8

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

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

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

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.

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CAUTION

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

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

PRECISION TIG® 225

F-9 F-9

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

The arc "flutters" when TIG weld­ing.

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

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.

The arc "pulsates" when AC TIG welding.

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

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

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

CAUTION

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

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

PRECISION TIG® 225

F-10 F-10

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

Black areas along weld bead.

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

1. This may be a welding proce­dure problem.

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

3877.

Weak high frequency - machine has normal welding.

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. 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).

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

CAUTION

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

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

PRECISION TIG® 225

F-11 F-11

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

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.

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

1. This may be a welding proce­dure problem.

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

3877.

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

CAUTION

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

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

PRECISION TIG® 225

F-12 F-12

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

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

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

1. If the machine location is in a
highly dirty environment with
conductive contaminant's, 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.

RECOMMENDED

COURSE OF ACTION

1. Check the high voltage trans­former (T3). The normal resis­tance of the secondary winding
of the high voltage transformer
is 12.5k ohms.

WARNING

ELECTRIC SHOCK CAN
KILL. When 115VAC is

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

3877.

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

2. CheckthevaluesofR3,and

C4.

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. 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.

3.

Perform the T1 Transformer

Test.

4. The control board may be
faulty. Replace.

1. Possible gas supply problems.

Consult your local welder/gas dis­tributor.

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CAUTION

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

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

PRECISION TIG® 225

F-13 F-13

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

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.

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

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.

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

CAUTION

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

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

PRECISION TIG® 225

F-14 F-14

Observe Safety Guidelines detailed in the beginning of this manual.

TROUBLESHOOTING AND REPAIR

PROBLEMS

(SYMPTOMS)

Stick electrode "Blasts Off" when arc is struck.

The stick electrode "sticks" in the puddle.

POSSIBLE AREAS OF

MISADJUSTMENT(S)

OUTPUT PROBLEMS

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.

RECOMMENDED

COURSE OF ACTION

1. Perform the SCR Bridge Test.

2. The control board may be
faulty. Replace.

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

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

1. Check work and electrode
cablesforlooseorpoorconnec­tions.

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

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

CAUTION

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

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

PRECISION TIG® 225

F-15 F-15

TROUBLESHOOTING AND REPAIR

HIGH FREQUENCY CIRCUIT DISABLE PROCEDURE

WARNING

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
or machine operator and will invalidate your factory warranty. For your safety and to avoid
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.

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

WARNING

HIGH VOLTAGE IS STILL PRESENT IN THE HIGH FREQUENCY CIRCUIT.

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

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PRECISION TIG® 225

F-16 F-16

TROUBLESHOOTING AND REPAIR

HIGH FREQUENCY CIRCUIT DISABLE PROCEDURE (continued)

FIGURE F.1 – SPARK GAP ASSEMBLY

.020 Spark Gap

LEFT SIDE OF MACHINE

PROCEDURE

1. Remove input power to the TIG 225 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 225 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.

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PRECISION TIG® 225

F-17 F-17

TROUBLESHOOTING AND REPAIR

T1 TRANSFORMER TEST

WARNING

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
or machine operator and will invalidate your factory warranty. For your safety and to avoid
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.

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® 225 Wiring Diagrams
3/8” nutdriver

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PRECISION TIG® 225

F-18 F-18

TROUBLESHOOTING AND REPAIR

T1 TRANSFORMER TEST (continued)

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

PRECISION TIG 225 CONTROL BOARD

J2

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

J3

PIN 3 (LEAD #204)
PIN 4 (LEAD #201)

PROCEDURE

1. Remove main supply power to the machine.

2. Using the 3/8” nutdriver remove the case wrap­around 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 225 ON.

J4

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

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

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PRECISION TIG® 225

F-19 F-19

TROUBLESHOOTING AND REPAIR

T1 TRANSFORMER TEST (continued)

PROCEDURE

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 be 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.

TABLE F.1 T1 TRANSFORMER VOLTAGE

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)

TO 115VAC

PLUG J4 PIN 3 (LEAD #232)

X1 TO X2 80 VAC

CHECK DURING FIRST 5 SECONDS OF POWER UP

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PRIMARY WINDINGS PRIMARY VOLTAGES

H1 TO H2 208VAC

H1 TO H3 230VAC

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

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PRECISION TIG® 225

F-20 F-20

NOTES

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PRECISION TIG® 225

F-21 F-21

TROUBLESHOOTING AND REPAIR

STATIC SCR TEST

WARNING

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
or machine operator and will invalidate your factory warranty. For your safety and to avoid
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.

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® 225 Wiring Diagrams
3/8” nutdriver
SCR Heat Sink Assembly Drawing

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PRECISION TIG® 225

F-22 F-22

TROUBLESHOOTING AND REPAIR

STATIC SCR TEST (continued)

FIGURE F.3 – Plug J2 Location on Control Board

PLUG J2 REMOVED

PRECISION TIG 225 CONTROL

J2

J3

TEST PROCEDURE

1. Remove main supply power to the TIG 225 and
remove the case wrap-around cover.

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

J4

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PRECISION TIG® 225

F-23 F-23

TROUBLESHOOTING AND REPAIR

CASE COVER REMOVAL AND REPLACEMENT PROCEDURE (continued)

FIGURE F.4 – SCR TEST POINTS

SCR2 CATHODE

SCR1 ANODE

SCR1 CATHODE/SCR2 ANODE

SCR3 ANODE/SCR4 CATHODE

SCR3 CATHODE

SCR4 ANODE

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TEST PROCEDURE (continued)

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.

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PRECISION TIG® 225

F-24 F-24

NOTES

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PRECISION TIG® 225

F-25 F-25

TROUBLESHOOTING AND REPAIR

ACTIVE SCR TEST

WARNING

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
or machine operator and will invalidate your factory warranty. For your safety and to avoid
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.

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® 225 Wiring Diagrams
3/8” nutdriver

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PRECISION TIG® 225

F-26 F-26

TROUBLESHOOTING AND REPAIR

ACTIVE SCR TEST (continued)

FIGURE F.5 – ACTIVE SCR TEST SETUP

SW1

R2

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.

TEST PROCEDURE

1. Remove main supply power to the TIG 225
machine.

V

SCR
under
test

R1

SW2

A

G

C

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

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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 Test

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

- Check the battery by shorting

PRECISION TIG® 225

F-27 F-27

TROUBLESHOOTING AND REPAIR

ACTIVE SCR TEST (continued)

FIGURE F.6 – SCR GATE LOCATIONS

SCR2 CATHODE

SCR1 ANODE

SCR1 CATHODE/SCR2 ANODE

SCR3 ANODE/SCR4 CATHODE

SCR3 CATHODE

SCR4 ANODE

PLUG J7

3

SCR1

1

S24018-4 (INSERTION SIDE)

SCR GATE LEADS/TEST POINTS

4

SCR4SCR3

SCR2

2

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TEST PROCEDURE (continued)

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 SW-2 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

PRECISION TIG® 225

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.

F-28 F-28

NOTES

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PRECISION TIG® 225

F-29 F-29

TROUBLESHOOTING AND REPAIR

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 volts

0 volts

2ms

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.

SCOPE SETTINGS

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

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

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

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

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PRECISION TIG® 225

F-30 F-30

TROUBLESHOOTING AND REPAIR

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

volts

2ms

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.

0volts

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SCOPE SETTINGS

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

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

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

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

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PRECISION TIG® 225

F-31 F-31

TROUBLESHOOTING AND REPAIR

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.

____________________________________________________________________

volts

50

0volts

2ms

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.

SCOPE SETTINGS

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

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

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

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

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

PRECISION TIG® 225

F-32 F-32

TROUBLESHOOTING AND REPAIR

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.

____________________________________________________________________

volts

50

2ms

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.

0 volts

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

SCOPE SETTINGS

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

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

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

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

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

PRECISION TIG® 225

F-33 F-33

TROUBLESHOOTING AND REPAIR

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.

____________________________________________________________________

volts

50

2ms

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.

0 volts

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

SCOPE SETTINGS

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

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

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

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

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

PRECISION TIG® 225

F-34 F-34

TROUBLESHOOTING AND REPAIR

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.

____________________________________________________________________

volts

50

2ms

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.

0volts

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

SCOPE SETTINGS

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

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

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

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

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

PRECISION TIG® 225

F-35 F-35

TROUBLESHOOTING AND REPAIR

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.

____________________________________________________________________

50

volts

2ms

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

0volts

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

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

SCOPE SETTINGS

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

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

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

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

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

PRECISION TIG® 225

F-36 F-36

TROUBLESHOOTING AND REPAIR

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.

____________________________________________________________________

50

volts

0volts

2ms

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.

SCOPE SETTINGS

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

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

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

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

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

PRECISION TIG® 225

F-37 F-37

TROUBLESHOOTING AND REPAIR

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.

____________________________________________________________________

volts

50

2ms

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 non­functioning 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.

0 volts

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

SCOPE SETTINGS

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

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

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

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

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

PRECISION TIG® 225

F-38 F-38

NOTES

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

PRECISION TIG® 225

F-39 F-39

TROUBLESHOOTING AND REPAIR

SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE

WARNING

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
or machine operator and will invalidate your factory warranty. For your safety and to avoid
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.

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

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

PRECISION TIG® 225

F-40 F-40

TROUBLESHOOTING AND REPAIR

SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (continued)

FIGURE F.7 – CASE BACK MOUNTING SCREWS

REAR PANEL
MOUNTING
SCREWS

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

PROCEDURE

1. Remove input power to the TIG 225 machine.

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

PRECISION TIG® 225

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.

F-41 F-41

TROUBLESHOOTING AND REPAIR

SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (continued)

FIGURE F.8 – FRONT PANEL MOUNTING SCREWS

FRONT PANEL
MOUNTING
SCREWS

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

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.

PRECISION TIG® 225

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.

F-42 F-42

TROUBLESHOOTING AND REPAIR

SCR BRIDGE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (continued)

FIGURE F.9 – PLUG J2 ON CONTROL BOARD

PLUG J2 REMOVED

PRECISION TIG 225 CONTROL

J2

J3

J4

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

DIODE
PIGTAIL
CONNECTION

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

PRECISION TIG® 225

F-43 F-43

TROUBLESHOOTING AND REPAIR

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 225 cutting any necessary cable
ties.

REPLACEMENT PROCEDURE

1. Carefully place the new SCR bridge assembly

in position in the TIG 225.

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 pos-

itive 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 transformer 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. Besureto
replace sleeving and secure with cable ties.
Position with harness and secure with cable
ties.

11. Position and install the case back and secure
with the screws previously removed.

12. Install the gas hose onto the solenoid valve.

13. Tighten the input cable strain relief.

14. Assemble the case wrap-around cover.

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

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.

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

PRECISION TIG® 225

F-44 F-44

NOTES

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

PRECISION TIG® 225

F-45 F-45

TROUBLESHOOTING AND REPAIR

POLARITY SWITCH

REMOVAL AND REPLACEMENT PROCEDURE

WARNING

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
or machine operator and will invalidate your factory warranty. For your safety and to avoid
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.

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

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

PRECISION TIG® 225

F-46 F-46

TROUBLESHOOTING AND REPAIR

POLARITY SWITCH

REMOVAL AND REPLACEMENT PROCEDURE (continued)

REMOVAL PROCEDURE

1. Remove the input power to the TIG 225
machine.

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

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 micro-switch 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.

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

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 connection 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.

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

PRECISION TIG® 225

F-47 F-47

TROUBLESHOOTING AND REPAIR

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.

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

13. Using the Allen type wrench replace the output

control knob.

14. Replace the case wrap-around cover.

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

PRECISION TIG® 225

F-48 F-48

NOTES

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

PRECISION TIG® 225

F-49 F-49

TROUBLESHOOTING AND REPAIR

HIGH VOLTAGE TRANSFORMER

REMOVAL AND REPLACEMENT PROCEDURE

WARNING

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
or machine operator and will invalidate your factory warranty. For your safety and to avoid
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.

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

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

PRECISION TIG® 225

F-50 F-50

TROUBLESHOOTING AND REPAIR

HIGH VOLTAGE TRANSFORMER

REMOVAL AND REPLACEMENT PROCEDURE (continued)

FIGURE F.11 – SECONDARY LEADS AT HIGH FREQUENCY STARTER BOARD

REMOVAL PROCEDURE

1. Remove input power to the TIG 225 machine.

2. Using the 3/8” nutdriver remove the case wrap­around 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 connect from
one primary lead to lead #231A. Cut any nec­essary cable ties.

5. Remove the lead splice from the other primary
lead that is connected to lead #236 and the C4
capacitor. See wiring diagram. Cut any neces­sary cable ties.

TRANSFORMER
SECONDARY
LEADS

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 225 machine.

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

6. Using the phillips head screwdriver remove the

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

PRECISION TIG® 225

F-51 F-51

TROUBLESHOOTING AND REPAIR

HIGH VOLTAGE TRANSFORMER

REMOVAL AND REPLACEMENT PROCEDURE (continued)

FIGURE F.12 – HIGH VOLTAGE TRANSFORMER MOUNTING INSULATORS

SLOTTED REAR
MOUNTING INSULATORS

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

FRONT MOUNTING

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.

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

7. Replace the case wrap-around cover.

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

PRECISION TIG® 225

F-52 F-52

NOTES

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

PRECISION TIG® 225

F-53 F-53

TROUBLESHOOTING AND REPAIR

MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE

WARNING

Service and repair should be performed by only Lincoln Electric factory trained personnel.
Unauthorized repairs performed on this equipment may result in danger to the technician
or machine operator and will invalidate your factory warranty. For your safety and to avoid
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.

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

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

PRECISION TIG® 225

F-54 F-54

TROUBLESHOOTING AND REPAIR

MAIN TRANSFORMER AND OUTPUT CHOKE ASSEMBLY

REMOVAL AND REPLACEMENT PROCEDURE (continued)

REMOVAL PROCEDURE

1. Remove input power to the TIG 225 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 sec-

ondary 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.

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.

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

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

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

PRECISION TIG® 225

F-55 F-55

NOTES

RETEST AFTER REPAIR

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

INPUT IDLE AMPS

Input Volts/Hertz Maximum Idle Amps

208/60 2.70 Amps
230/60 3.00 Amps

OPEN CIRCUIT VOLTAGES

Stick Mode OCV

TIG Mode OCV

AC 70 - 75VAC

DC 55 - 66VDC

AC 70 - 80VAC

DC 60 - 66VDC

MAXIMUM ACCEPTABLE OUTPUT VOLTAGE -

AT MINIMUM OUTPUT SETTINGS

DC TIG Mode 5 Amps @ 12 Volts

MINIMUM ACCEPTABLE OUTPUT VOLTAGE -

AT MAXIMUM OUTPUT SETTINGS

DC TIG Mode 225 Amps @ 29 Volts

RECOMMENDED METERS FOR MACHINE OUTPUT TESTS

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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.

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PRECISION TIG® 225

F-56 F-56

NOTES

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PRECISION TIG® 225

G-1 G-1

ElectricalDiagrams .....................................................................G-1

WiringDiagram(G5646) ...............................................................G-2

EntireMachineSchematic(G5647).......................................................G-3

Control PC Board Schematic #1 (G5640) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-4

Control PC Board Schematic #2 (G5640) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-5

Control PC Board Schematic #3 (G5640) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-6

Control PC Board Assembly #1 (G5641) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-7

Control PC Board Assembly #2 (G5641) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-8

ByPass PC Board Schematic (S22530) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-9

TABLE OF CONTENTS - DIAGRAM SECTION

ByPass PC Board Assembly (L10121) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......G-10

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PRECISION TIG® 225

R

CLEVELAND , OHIO

G5646

A

SCR4

S

CR

2

S

CR

1

D

C

B

A

R

EAR GANG

L1

ELEC

TRO

DE

T3

NC

N

O

MI

CRO

-SWITCH

T2

L2

L3

C3

SCR3

H1

H

G

311A

312A

OP

EN

CLOS

ED

C

LOSED

G4

216

G3

2

1

8

G2

G1

217

220

AC

E

F

PC BO

ARD

CONTR

OL PC BOA

RD

D1

S2

SV1

GASVAL

VE

S2

A

BYPASS/

STABI

LIZER

H1

X1

X2

R 222

W 221

WO

RK

R2

ARC

STARTER

A

S'BLY

237

C4

R3

235

J3

236A

SP

ARK

GAP

284A

285A

AC
DC+
D

C-

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

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

POLARITY SWI

TCHMICR

OSWI

TCH

(

REAR V

IEW,

SHOWN IN AC POSITION

)

115V

AC

18V

AC

18V

AC

78V

AC

T1

POL

ARITY

SWITCH

H3
H2

H3 (

HIGH

)

H2 (LO

W)

L4

POS

X4
X5

X

3

X

6

X7

X8

C2

C

1

201

204

2

09

210

231

2

32

AUTO

BALANCE

LED

PULSE

F

REQ

LED

AC

B

ALA

N

CE

CO

NTRO

L

PULSE

CO

NTRO

L

POS

TFLO

W

CO

NTRO

L

STICK LE

D

TIG

LED

DIGITAL
DISPLAY

T

HER

M

A

L

LED

OUTPUT

CO

NTRO

L

M

ODE

SWI

TCH

B

(L1)

W

(L2

)

P

OWER

SWITCH

S1

G

FAN

115V

AC

+

(

)

(

)

_

DC

1

15VAC

238

239

210

209

201

313

314

1

2

3

4

6

5

7

11

12

R

222

W 221

1
2

89

10

RECEPTACL

E

C

A

B

B

10K

A-B

F

E

D

C

ATMINI

MUM

D

REMO

TE

TM

AMPTROL

O

PTIONAL

A

E

REMO

TE

J2

J1

A

1

J5

2

3
4
5
6

C
B

D

E

216A

2

4

0

L5

204

2

36

231A

2

60

R4

220A

245

R

5

2

18A

244

TRIG

GER

POWER

R1

284B

285B

285

2

8

4

AC

X2

F

RONT

GANG

RG

G

G

Y

220A

218A

231B

J4

3

1

1

312

245

244

216A

240

314

S4

CHOKE

313

S

EE RATING PLATEFOR SPECIFIC VOLTAGES

2

30 or 400-415 or 575 VOLT CONNECTION

H

1 and H3 (HIGH)TO PO

W

E

R S

W

I

TCH.

208 or 38

0 or 460

VOLT

CON

NECTION

H1 and H2 (LOW) TO POWER SWITCH.

H

3 NOT CONNECTED; INSULATE.

H2 NOT CON

NECTED; INSULATE.

C1 AND C2 MUST ALWAYS BE CONNECTED

ACROSS TRANSFORMER PRIMARIES

VOLTAGE RECONNECTION

(AS SHOWN & AS SHIP

PED F

ROM FACTORY

)

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

IT

E

LEAD COLORIN

G

COD

E:

CONNE

CTORPI

NNUMBER

S:

VIEWOFCONNE

CTORONPCBO

ARD

123 7

8

14

LATC

H

EXAMPLE: THIS I

S PIN7

OF

CONNE

CTORJ4

COMPONENTVALUE

UN

IT

S:

RE

SIS

TOR

S:

CAPACITOR

S:

OHMS/WATTS

MFD

/V

OLTS

J4

ELECTRICAL SYMBOL

S PER E1537.

4

3

2

1

235

260

G4

220

G2

G1

216

G3

218

217

1

2

3456

7

8

DC

POS

S

HUN

T

X

1

236

232A

INPUTPLUG(208V/230V ONLY)

TO GROUND PER

NATIONAL ELECTRIC

CODE

285

284

G4

G2

123

4

G3

G1

P7
J7

1

2

3

J6

4

CONNE

CT

GR

EENLEA

DTOGROUNDPER

NA

TIO

NALANDLOCAL EL

ECT

RICAL C

ODE

CONNECT

BLACKAND WHITE

LEADS

TO S

UPPLYCIRCUI

T

B

(L1)

W

(L2

)

G

380V AND ABOVE

208V/230V ONLY

311

312

115V

AC

231A

232

CB1

233

232A

231B

231

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
CB1

20A CIRCUIT BREAK ER(208V/230V O NLY)

6A CIRCUIT BRE AKER (380V AND AB OVE)
D1

FREE WHEELING DIODE
L1

OUTPUT INDUCTOR (CHOKE)
L2,L3 HIGH FREQUE NCY INDUCTORS
L4,L 5 RF TORO ID CHOKE S
R1,R2 HOLDING RE SISTORS, 100/100W
R3

PHASE SHIFT RESISTOR, 200/ 100W
R4,R5 MICRO S TART RESISTORS, 12/100W
S1

INPUT POWER SWITCH
S2

POLARITY SWITCH
S2A

MICRO SWITCH ON PO LARITY SWITCH
S4

MAIN CHOKE THERMOSTAT
SCR1,2,3,4 MAIN POWER SCR'S
SV1

GAS SOLENOID VALVE, 115VAC
T1

MAIN TRANSFORMER
T2

HIGH VOLTAGE TRANSFORME R
T3

HIGH FREQ UENCY TRANSFORM ER

R

ECEPTACLE

(

BACK VIEW)

C5

C6

G-2
WIRING DIAGRAM - COMPLETE MACHINE - ALL CODES (G5646)

ELECTRICAL DIAGRAMS

G-2

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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.

PRECISION TIG® 225

EN-170

S

O

L

I

D

E

D

G

E

E

NGINEERINGCONTROLLE

D

MANUFACTURER

:

No

RELEASEDFR

OM XA.02

G5647

Precision Ti g 225

MACHINE SCHEMATI C

NONE

G4588

Jbarto

R

Sam

ode

ll

Ap

prove

D

RAWN

BY:

DESIGNI

NFO

RMATI

ON

ENGINEER:

AP

PRO

VED

:

REFERENCE:

EQ

UIPMENT

TYPE:

SUBJECT:

SCALE:

MATERI AL
DISPOS

IT

ION:

APPROVAL
DATE:

PROJECT
NUMBER:

NA

C

RM38254

1

PAGE ___ OF

___

1

DOCUMENT
NUMBE

R:

DOCUMENT
REVISION:

THIS DOCUMENT CONTAINS PROPRIETARYINFORMATION OWNED BYLINCOLN GLOBA

L, INC.

AND MAYNOT BE DUPLICATED, COMMUNICATED

TO O

THER PARTIES OR US

ED FOR

ANYPURPOS

E WITHOUTTHE EXPRES

S WRIT

TEN PERMISSION

OF LINCOLN GLOBAL, INC.

PRO

PRIETARY & C

ONFIDENTIAL:

A

T

HE INFORMATIONON THIS

PRINTIS FOR

REFER

ENC

E

ON

LY.

COMPONENTSAND

CIRCUITRY MAY

BE

DIFFER

ENT

FROM

AN ACT

UAL MACHIN

E.

06/20/2006

CHANGEDETAIL:

G

5647

LEADCOLOR

COD

E:

B-BLACKORGRAY
G-

GREEN

O-

ORANGE
R-REDORPINK
U-BLUE
W-WHIT

E

Y-YELL

OW

C

OM

PONE

NT VALUEUNIT

S:

CAPA

CITOR: MFD/V

OLT

S

RE

SISTO

R: OHMS/W

ATT

S

CONNE

CTORPINNUM

BER

S:

VIEW OF CONNECTORON PC BOARD

1

2

6

7

12

LA

TCH

EX. 12 PIN CONNECTOR

LABELS:

C

OMM

ON

FRAME

GROUND

EA

RTHGROUND

SCR4

SCR3

SCR1

SCR2

M

AINSC

R

RECTIF

IE

R

D1

OUTPUT

INDUCTOR

AC

D

C

DC

DC

DC

AC

AC

AC

++

-

-

POLARITYSWITCH

SHUNT

MAIN

TRANSFORMER

X1

X2

H1

H2

H3

L2

L

1

+

-

250VAC

.0047/

400A/200mV

S

2

C1

C2

L

1

DC

+

DC

-

DC

+

DC

-

G1
G2
G3
G4
218
217
216
220

SCR3,SCR2 CATHODE
SCR1 CATHODE

SCR4 CATHODE

SCR1,SCR4 ANODE

SCR1 GATE
SCR2 GATE
SCR3 GATE
SCR4 GATE

216A

G4
G3
G2

G1

220

217
218

FREE

WHE

ELINGDIODE

POWER SWITC

H

R 222

(-)

W

221(+

)

W 221

R 222

S

HUNT (+)

S

HUNT (-)

1J1

2J1

TOROI

D

LOW

HIG

H

T1

BYPASS ASSEMBL

Y

R

1

WORK

SV

1

G

A

S

SOLENOID

FAN

X7

X8

HIGH FREQ.

TRANSFORMER

100/100

T2

S

F

C3

.0015/

12KV

SPA

RK

GAP .020

R

3

200/100

C

4

15/250

H

IGH

VOLTAG

E

T

R

ANSFORMER

L2

L3

T3

ELECT

ROD

E

HOL

DIN

G

RESISTORS

231

231

232

236B

237

2

38

239

236

H

I-FREQ (115VAC)

GAS (115VAC)

F

AN (115VAC)

2

35

260

314

3

13

T

HERMOSTATINPUT

235

232

260

232A

115

VAC IN

4J4
1J4

2J4

3

J4

X5

X6

X3

X4

1

8

VAC

C

ONTROLBOARD SUPPL

Y

1

8VAC

TRIGGER CIRCUIT

209

210

201

204

AUX.WINDINGS OF

MAIN T

RAN

SFORME

R T1

C

HOKE TSTAT

(SCHEMATIC S22530

)

B

YPASS/STABILIZER

PC

B

115VA

C

(115VA

C)

11

5VAC

5.5 OHMS
TYP.

1

4.5 KOHMS

T

YP.

1

2.5 OHM

TYP.

1

2

.5 OHM TYP.

T1

T1

HI-FR

EQ CIRCUIT

3

DIGIT

METER

CWR1CW

10K

RECEPTACLE

TM

OPTIONAL AMPTROL REMOTE
CONTROL

AND ARC S

TART SWITCH

A

B

C

D

E

F

U

N

R

B

W

10K

TOROI

D

C

A

B

OUTPUTCONTRO

L

(ENCO

DER)

+5Vref

+

5Vr

ef

C

W

R2

C

W

10K

+

5Vr

ef

CWR3CW

10K

+5Vref

B

ALANCE

PU

LSE FREQ

UEN

CY

POSTFLOW

+

15V

M

ODE

STICK
(

RED)

TIG

(GR

EEN

)

MICRO-

P

ROCESSOR

AUT0BALA

NCE

(GREE

N)

FRE

QUE

N

C

Y

(GREE

N)

THERMAL
(YELLOW)

SEE

RATIN

G PLATE

FOR

SPE

CIFIC

VOLTAGES

230or400-415or575

VOLT C

ONNE

CTIO

N

H

1 and H3(HIG

H) T

O P

OWER SWI

TCH.

208 or380 or460

VOLT C

ONNE

CTIO

N

H

1 and H2(LO

W) T

O P

OWER SWI

TCH.

H3NOT CONNE

CTED; I

NSULAT

E.

H2NOT CONNE

CTED; I

NSULAT

E.

C

1AN

D C

2

M

UST AL

W

A

YS BECONNECTE

D

A

CR

OSS

TRAN

SFORMER PRIMARIES

VOLTAGE RECONNECTION

(

AS S

HOWN

& A

S SHIPPE

D FROM FA

CTO

RY)

R2

C

LOSED

I

N DC

311

312

311

312

MICRO SWITCH INPUT

5

J3

6

J3

N.C.

R5

12/100

E

ACH

R4

220A

218A

ARCSTARTER

ASSEMBL

Y

1J3

2

J3

7J3

8J3

4J3

3J3

100/100

284A

285A

285B

2

84B

284

2

85

MIC

RO SWITCHC

LOSE

D INDC

OPEN I

N A

C

W

B

G

INPUT PLUG

216

BACKGROUNDRESISTORS

BACKGROUND AC INPUT

BACKGROUND ( - )

BACKGROUND ( + )

240

11J3

9J3

10J3

12J3

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

1J5

3J5

2J5

5J5

6J5

METER

INTERFA

CE

LE

D I

NTERFA

CE

J2

J3

J4

J5

J6

J1

+15V

(G

REEN)

CONTRO

L PCB MAIN

COMPONENT &

DIA

NOSTI

C LE

D LAYOUT

(VIEWED F

ROM

COMPONENT SIDE)

AUTO LOCAL/ REMOTE
STI CK MODE

:

ALWAYS LOCAL

TIG MODE

:

REMOTE IFP LUGGED

LOCAL IFUNPL UGGED

2 PIN

6 PIN

8 PIN

12 PIN

4 PIN

4PIN(W

HIT

E)

PROGR

AMMING

CONNECTOR

HI-FREQ BYPASS
CONNECTI ON

SCH

EMATIC G5640-

ASSEMBLY

G5641-

CONTR

OL PC BOA

RD

+5V

30 S

1S

20 HZ

O

FF

MA

X.

PENETR

ATI

ON

AUTO

MA

X. CLEANING

5-2

30A

A

Cand DC

+5V

+5Vref

O

UTPUT CONTROL &
MODE SETTINGS ARE
M

EMORIZED AT POWER

-

DOWN AND RECALLED

A

TPOWER

-U

P

S

CR

GAT

ING & SNUBBE

R

+1

5V

+5V

MICRO-STA

RT

CIRCUIT

+1

5V

OUTP

UT REGU

LATOR

+1

5V

115V CIRC

UIT

T

RIAC& OPTO-TRIA

C

D

RIVE

R

+1

5V

(PCB AS'BLY

L10121-1

)

435 OHMS TYP.

12 OHMS TYP.

FAN RUNS F OR 5 S AT POWER- UP
STOPS AT

I

DLE 8 MINUT ES

AFTER WELDING.

COMPONE

NT LOCATIONDESC

RIPTIONS ARE AS VIE

WED

FROM

FRONTOF

MACHIN

E U

NLESS STATE

D

OT

HERW

ISE

G4
G

3

G2

G1

IN-LINE

CONNECTO

RJ7

4
3
2

1

InF

ront ofmain

t

ransformer,

A

ttachedtoBase

Leftside of

Machine

n

ear fron

t

R

e

ar Panel

R

ight Side

R

i

ght Side of S

CRB

ridge

R

e

ctifier

.

T

op o

f

M

achine

behind C

hoke.

R

i

ghtside o

f

M

achine

a

bove Choke Coil.

R

i

ght side ofmachine,

frontofgas

solenoid,

att

ached

toB

ase

A

ttached

toPow

e

r S

w

i

tch

S

1

Front Panel Leftside

F

ront Panel Center

Front Panel Top

I

nside hi-freq box on

r

ight side ofmachine

n

ear fron

t

R

e

ar ofmachine a

t

t

ached

t

o

base,

below fan

0.1 HZ

R

ight

frontside of

Main Trans

form

er

Between SCR

Bridge halves

behind choke

.

M

ounted

tof

ron

t

s

ide

ofhi-f

req box on

right

side o

f m

achine

n

ear front.

Lower leftside of

Polar

ity Sw

itch

Inside

hi-

freq

box

on

r

ight side ofmachine

near

fron

t

BACKGROUND AC INPUT

245
244

216A

240

TWISTED PAIRS

PO

STFL

OW

FR

EQUENCY

(NOR

MALLY

CLOSE

D

O

PEN AT 135CTYP.)

R

ight rearside ofMain

Transformer

80 VAC

On top of

Main

T

ransfor

m

e

r

Inside

sleevingat

top

leftside of

Main Rectifier

DISPLAY PRESET AT

IDLE

ACTU

AL AMP

WHE

N WEL

DING

NOHOL

D FUNCTIO

N

(DISA

BLE

D INSTICK)

OUTP

UT CONTROL

X1

SOFTWARE

VE

RSION LABEL

6

5V I

N

D

C

75V INAC

POWE

R-UP

SEQUENCE

METERANDMODEDISPLAYTHEPREVIOUSOUTP

UT

CONTR

OL ANDMODESETTINGS. FAN

RUNSFO

R5

SECOND

S. IF MODEI

STI

G, GASFLOWSFOR

ATI M

E

S

ET BYTHEPOSTFLOW

KNO

B. OUTPUT ISH

OT IF

MODEISSTICK. I

NTI G MODEOUTPUT ISCOLDUNTIL

TRI

GGERISCLOSED

(DISP1)

A1

S

1

METER,

ENCODER,S

WITCH, LEDs,

AND

ALLP

OTE

N

TIOMETER

S

A

RE

MOUNTEDONPC

BOARD

TYPIC

ALO

CV

TO

GGLE BETWEEN TIG &

S

TI

CK.

HI

-F

REQ, GAS, BALANCE
CONTROL, P ULSE
FREQUENCY, &
MICRO-

STARTCIRCU

IT

ARE DISABLED I N STICK

LED

1

LE

D 3

LE

D 4

LED

5

LE

D 2

THERMAL
(YELLOW)

LE

D 6

NEXTTO MODE S WITCH

NEX

TTOBALANCE POT.

NEX

TTOPULSE

FREQUENCY P

OT

.

N

EX

T

TOM

E

TER

NEX

TTO M

ETER

NEX

TTOM

ODE SWITCH

OFF

IN STICK AND DC TIG

OFF

IN STICK, BLI NKS AT

FREQUENCY RATE

TWO

T

HERMAL LEDs TO

LIGH

T

THROUGH

BACK

-LIT T

HERMAL

SYMBOL

MO

DE

MICRO-

PROCESSOR

1J6

2J6

3

J6

4J6

+5Vref

DATA

S

CLK

XRES

P

ROGRAMMI

NGC

ONNECTOR

FORS

OFT

WAREUPGRADE

HI-FREQ

BYPASSCONNE

CTI

ON

FR

OM BOTT

OM L

EFT

MOUNTINGHOLETO

SHE

ET

MET

AL

Left fr

ont

SCR4

SCR2

SCR1

SCR3

G4

216

G3

2

1

8

G2

G1

217

AC

D1

+

( )

( )

_

216A

X2

220

218A

POS

SHUNT

220A

DC

216A

R

222R 222

W

222

TO0 CO

PPER BAR

B

OTTOM

CO

PPER

BAR

6

GA.

F

L

EX LEADS

7

GA. FLEX LEAD

A

LUMINUM BAR

FARTHEST LEFT
SCR ( VI EWED
FROM FRONT

)

FARTHEST RIGHT

SCR

(VIEWED

FROM

FRONT)

S

CR

H

E

ATS

INK

SC

R BRI

DGE AN

D POLARITYSWITCH CONNECTION DETAIL

240

POS

DC

285

284

OUTPUT

INDUCTOR

X1

MOU

NTIN

G HO

LE

Gang D

GangA

gang

B

GangC

Reargang

G

Rearg

ang H

GangF

Gang E

GAN

G LOCATIONS

ARE

VI

EWE

D FROM REAR

OF

S

WITC

H

POLA

RITYS

WIT C

H

MICROS

WIT C

H

A-C, D

-E,

B-F

B-D, C

-E,

A-F,

G-H

B-

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

OPEN

CL

OSED

CL

OSED

AC
DC+
DC-

3

11

312

MICRO SWITC

H

U

NUSED TERMINA

L

RECONNE

CT ISDONEAT

POWERS

WIT

CH

C

e

nter ofmachine

T

op rear

SEE

C

ONNECTIO

N

DETA

IL

SETPOINT

PHAS

E_FI

RE

INTERFA

CE

INTERFA

CE

AC/DC

THERMOSTAT

DETERMINE IF HI-FREQ IS
CON

TI

NUOUS OR START

ONLY,

M

IN. CURRENT, AND

BALANCE CONTROL

DISABLE OUTPU

T

&HI-FREQ

IF T

HERMOSTATOPEN

CURREN

T

FEEDBACK

Iarc

PHASE
D

ETECT

OR

POWER SUPPLY

+1

5V

+5V

+5V

re

f

-15V

P

HASE

TO MICRO PROCESSOR
AND SCR GA

TI

NG

PHASE

PHASE

A

UTO
LOCAL/
R

EMOTE
CONTRO

L

DET_REM

REM_SENSE

REM_POT

TO MICRO
PROCESSSOR

DET_REM

RE

M_

SENSE

RE

M_POT

From Auto Loc/R

em

P

olling sign

al

Hi

= Loc

al

Remote cont

rol

TRIGGE

R

INTERFA

CE

TRIGGER

TRIGGER

TO MICRO
PROCESSOR

DO N

OT

REVERSE LEADS

209&21

0, USED FOR SCR

PHASE

TIMING

115V

5000V

HI-FREQ

OFF

IN STICK

STAR

T

ONLY I N DC TIG

CON

TI

NUOUS IN AC TIG

Right front

C

ent

er fro

nt

TYP

. RPM:
1600 RPM 60Hz
1340 RPM 50Hz

1

5 - 20 OHM

GATE-CATHO

DE

R

ESISTANCE TYP.

F

IRE_SCR

BG

-15V

RF
CHOKES

+15V

-1

5V

+5V

+2

4V

+5V

+24V

+5V

re

f

+

24

V

+5V

re

f

+2

4V

DC

AC

POS

Gang

D

Gang

A

Gang

C

Gang

G

Gang

B

Gang

H

Gang

E

G

ang F

CBW

CBW

CBW

CBW

CBW

CBW

CBW

CBW

CBW =CONNECT ED
B

YSW

ITC

H

T

HESE CONN EC

TIO

NS

ARE

M

ASE BY POLARITY

SW

IT

CH, THEY ARE N

OT

P

HYSICAL LEADS

CBW

SEE CONNECTION DETAIL

B

ALANCE

CONTR

OLIS

DISABLEDINSTICK

AND

D

CTI

G

P

ULSEF

REQUENCYIS

DISABLEDINSTI

CK

115

VAC

C

B

1

231A

231B

233

232A

C6

C5

.

22/400V

2

0A (208V/230V)

6

A (3

8

0

V & ABOVE

)

SC

R1

SC

R3

SC

R2

SC

R4

4 RED LED'S

BALANCE

MI

CRO

ST

ART

GA

S

FA

NHF

AC

LOCAL

GREE

N L

ED'S

TROU

BLE SHOOTING LED'S

PRESEN

T O

NLY O

N

PCBREVI

SIONB O

R LATER

G-3
SCHEMATIC - COMPLETE MACHINE - ALL CODES (G5647)

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

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

ELECTRICAL DIAGRAMS

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

PRECISION TIG® 225

G-3

G-4
SCHEMATIC - CONTROL PC BOARD #1 (G5640)

ELECTRICAL DIAGRAMS

G-4

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

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

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

PRECISION TIG® 225