1 - Miller Electric

AUTOARCJ
OWNERS
MANUAL
Read and follow these instructions and all
safety blocks carefully.
Have only trained and qualified persons
install, operate, or service this unit.
Call your distributor if you do not understand
the directions.
Auto Arcfi Model 255
DC/CV Welding Power Source/Wire Feeder
For GMAW And FCAW Welding
Uses .023 .045 Hard Wire And .030 .045 Flux Cored Wire
200 Amperes, 28 Volts DC At 60% Duty Cycle
Uses Single-Phase Input Power
Overheating And Motor Overload Protection
Includes Gun And Shielding Gas Valve
December 1995 Form: OM-157 066D
Effective With Serial No. KG034070
~
1I~fl
~l
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Give this manual to the operator.
For help, call your distributor
or: MILLER Electric Mfg. Co., P.O. Box 1079,
Appleton, WI 54912 414-734-9821
auto_arc 7/93 ST-157 072-A PRINTED IN USA
-.

.1
MILLERS TRUE BLUEfi LIMITED WARRANTY
Effective January 1, 1995
(Equipment with a serial number preface of KD or newer)
This limited wsrrsnty supersedes eli previous MILLER wsrrsnties snd is esclusive with no other guarantees or wsrrenties expressed or implied.
LIMITED WARRANTY Subject to the terms snd conditions below, MILLER Electric
Mt g. Co., Appleton, Wisconsin, wsrrsnts to its originsl retsil purchaser that new
MILLER equipment sold after the effective dale of this limited warranty is free of de
fects in material and workmanship at the time it is shipped by MILLER. THIS WAR
RANTY IS EXPRESSLY IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FIT
NESS.
Within the warranty periods listed below, MILLER will repair or replace any war
ranted parts or components that fail due to such defects in material or workmanship.
MILLER must be notified in writing within thirty (30) days of such detect or failure, at
which lime MILLER will provide instructions on the warranty claim procedures lobe
followed.
MILLER shall honor warranty claims on warranted equipment listed below in the
event of such a failure within the warranty time periods. All warranty lime periods
start on the dale that the equipment wax delivered to the original retail purchaser, or
one year after the equipment is sent to a North American distributor or eighteen
months aher the equipment ix sent to an tntemational distributor.
1. 5 Years Parts 3 Years Labor
Original main power rectifiers
Inverters (input and output rectifiers only)
2. 3 Years Parts and Labor
*
Transtormer/Rectifier Power Sources
Plasma Arc Culling Power Sources
Semi-Automatic and Automatic Wire Feeders
Inverter Power Supplies
Inlellitigs
Robots
3. 2 Years Parts and Labor
Engine Driven Welding Generators
(NOTE: Engines are warranted separately by the engine manufacturer.)
Air Compressors
4. 1 Year Farm and Labor
*
Motor Driven Guns
Process Controllers
IHPS Power Sources
Water Coolant Systems
HF Units
Grids
Spot Welders
Load Banks
SDX Transformers
Running Gear/Trailers
Plasma Culling Torches (except APT, ZIPCUT & PLAZCUT Models)
Tecumseh Engines
DeuI.z Engines (outside North America)
Field Options
(NOTE: Field options are covered under True Bluefi for the remaining
warranty period of the product they are installed in, or for a minimum ot
one year whichever is greater.)
6 Months Batteries
6. 90 Days Parts and Labor
MIG Guna/TIG Torches
APT, ZIPCUT & PLAZCUT Model Plasma Culling Torches
Remote Controls
Accessory Kits
Replacement Parts
MILLERS True Bluefi Umited Warranty shall not apply to:
1. Items furnished by MILLER, but manufactured by others, such as engines or
trade accessories. These items are covered by the manufacturers warranty, if
any.
RECEIVING-HANDLING
2. Consumable components; such as contact tips, culling nozzles, contactorx
.and relays or pans that tail due to normal wear.
3. Equipment that has been modified by any party other than MILLER, or equip
ment that has been improperly installed, improperly operated or misused
based upon industry standards, or equipment which has not had reasonable
and necessary maintenance, or equipment which has been used for operation
outside of the specifications for the equipment.
MILLER PRODUCTS ARE INTENDED FOR PURCHASE AND USE BY COMMER
CIAL/INDUSTRIAL USERS AND PERSONS TRAINED AND EXPERIENCED IN
THE USE AND MAINTENANCE OF WELDING EQUIPMENT
In the event of a warranty claim covered by this warranty, the escfusive remedies
ahall be, at MILLERS option: (1 (repair; or (2) replacement; or, where authorized in
writing by MILLER in appropriate cases, (3) the reasonable cost of repair or replace
ment at an authorized MILLER service station; or (4) payment of or credit for the pur
chase price (less reasonable depreciation based upon actual use) upon retum of the
goods at customers risk and expense. MILLERS option of repair or replacement
will be FOB., Factory at Appleton, Wisconsin, or FOB. at a MILLER authorized ser
vice facilrty ax determined by MILLER. Therefore no compensation or reimburse
ment for transportation costs of any kind will be allowed.
TO THE EXTENT PERMITTED BY LAW, THE REMEDIES PROVIDED HEREIN
ARE THE SOLE AND EXCLUSIVE REMEDIES. IN NO EVENT SHALL MILLER BE
LIABLE FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL
DAMAGES (INCLUDING LOSS OF PROFIT), WHETHER BASED ON CON
TRACT, TORT OR ANY 0TH ER LEGAL THEORY.
ANY EXPRESS WARRANTY NOT PROVIDED HEREIN AND ANY IMPLIED WAR
RANTY, GUARANTY DR REPRESENTATtON ASTD PERFORMANCE, AND ANY
REMEDY FOR BREACH OF CONTRACT TORT OR ANY OTHER LEGAL
THEORY WHICH, BUT FOR THIS PROVISION, MIGHT ARISE BY IMPLICATION,
OPERATION OF LAW, CUSTOM OF TRADE DR COURSE OF DEAUNG, IN
CLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS
FOR PARTICULAR PURPOSE, WITH RESPECT TO ANY AND ALL EQUIPMENT
FURNISHED BY MILLER IS EXCLUDED AND DISCLAIMED BY MILLER.
Some states in the U.S.A. do not allow limitations of how long an implied warranty
lasts, or the exclusion of incidental, indirect, special or consequential damages, so
the above limitation or exclusion may not apply to you. This warranty provides spe
cific legal rights, and other rights may be available, but may vary Irom state to state.
In Canada, legislation in some provinces provides tor certain additional warranties
or remedies other than as stated herein, and to the extent that Ihey may not be
waived, the limitations and exclusions set out above may not apply. This Limited
Warranty provides specific legal rights, and other rights may be available, but may
vary from province to province.
Before unpacking equipment, check carton for any damage that may have occurred during shipment. File any claims for loss or damage
with the delivering carrier. Assistance for filing or settling claims may be obtained from distributor and/or equipment manufacturers
Transportation Department.
When requesting information about this equipment, always provide Model Designation and Serial or Style Number.
Use the following spaces to record Model Designation and Serial or Style Number of your unit. The information is located on the rating label
or nameplate.
Model
__________
Serial or Style No.
Date of Purchase
U
miller 6/95

ARC WELDING SAFETY PRECAUTIONS
ELECTRIC SHOCK can kill.
Touching live electrical parts can cause fatal shocks
or severe burns. The electrode and work circuit is
electrically live whenever the output is on. The input
power circuit and machine internal circuits are also
live when power is on. In semiautomatic or automatic
wire welding, the wire, wire reel, drive roll housing,
and all metal parts touchin9 the welding wire are
electrically live. Incorrectly installed or improperly
grounded equipment is a hazard.
1. Do not touch live electrical parts.
2. Wear dry, hole-free insulating gloves and body protection.
3. Insulate yourself from work and ground using dry insulating
mats or covers.
4. Disconnect input power or stop engine before installing or
servicing this equipment.
1.
2.
3.
a WARNING ARC WELDING can be hazardous.
PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH. KEEP CHILDREN
AWAY. PACEMAKER WEARERS KEEP AWAY UNTIL CONSULTING YOUR DOCTOR.
In welding, as in most jobs, exposure to certain hazards occurs. Welding is safe when precautions are taken. The
safety information given below is only a summary of the more complete safety information that will be found in the
Safety Standards listed on the next page. Read and follow all Safety Standards.
HAVE ALL INSTALLATION, OPERATION, MAINTENANCE, AND REPAIR WORK PERFORMED ONLY BY
QUALIFIED PEOPLE.
/,..
9~-22-
5. Properly install and ground this equipment according to its
6.
7.
Owners Manual and national, state, and local codes.
Turn off all equipment when not in use.
Do not use worn, damaged, undersized, or poorly spliced
cables.
8. Do not wrap cables around your body.
9. Ground the workpiece to a good electrical (earth) ground.
10. Do not touch electrode while in contact with the work (ground)
circuit.
11. Use only well-maintained equipment. Repair or replace
damaged parts at once.
12. Wear a safety harness to prevent falling if working above floor
level.
13. Keep all panels and covers securely in place.
ARC RAYS can burn eyes and skin; 1. Wear a welding helmet fitted with a proper shade of filter NOISE can damage hearing.
(see
ANSI Z49.1 listed in Safety Standards) to protect your face and
eyes when welding or watching.
Arc rays from the welding process produce intense 2. Wear approved safety glasses. Side shields recommended.
heat and strong ultraviolet rays that can burn eyes 3. Use protective screens or barriers to protect others from flash
and skin. Noise from some processes can damage and glare; warn others not to watch the arc.
earIng.
4. Wear protective clothing made from durable, flame-resistant
material (wool and leather) and foot protection.
5. Use approved ear plugs or ear muffs if noise level is high.
FUMES AND GASES can be hazardous 5. Work in a confined space only if it is well ventilated, or while
4~ to your health. wearing an air-supplied respirator. Shielding gases used for
Welding produces fumes and gases. Breathing
these fumes and gases can be hazardous to your
welding can displace air causing injury or death. Be sure the
breathing air is safe.
ea .
6. Do not weld in locations near degreasing, cleaning, or spraying
1.
2.
Keep your head out of the fumes. Do not breathe the fumes.
If inside, ventilate the area and/or use exhaust at the arc to
operations. The heat and rays of the arc can react with vapors to
form highly toxic and irritating gases.
remove welding fumes and gases.
7. Do not weld on coated metals, such as galvanized, lead, or
3. If ventilation is poor, use an approved air-supplied respirator. cadmium plated steel, unless the coating is removed from the
4. Read the Material Safety Data Sheets (MSDS5) and the weld area, the area is well ventilated, and if necessary, while
manufacturers instruction for metals, consumables, coatings, wearing an air-supplied respirator. The coatings and any metals
and cleaners. containing these elements can give off toxic fumes if welded.
WELDING can cause fire or explosion.
Sparks and spatter fly off from the welding arc. The
flying sparks and hot metal, weld spatter, hot
workpiece, and hot equipment can cause fires and
burns. Accidental contact of electrode or welding
wire to metal objects can cause sparks, overheating,
or fire.
Protect yourself and others from flying sparks and hot metal,
5.
6.
7.
8.
Watch for fire, and keep a fire extinguisher nearby.
Be aware that welding on a ceiling, floor, bulkhead, or partition
can cause fire on the hidden side.
Do not weld on closed containers such as tanks or drums.
Connect work cable to the work as close to the welding area as
practical to prevent welding current from traveling long,
possibly unknown paths and causing electric shock and fire
hazards.
Do not weld where flying sparks can strike flammable material. 9. Do not use welder to thaw frozen pipes.
Remove all flammables within 35 ft (10.7 m) of the welding arc. 10. Remove stick electrode from holder or cut off welding wire at
If this is not possible, tightly cover them with approved covers, contact tip when not in use.
4. Bealertthatweldingsparksandhotmaterialsfromweldingcan 11. Wear oil-free protective garments such as leather gloves,
through small cracks and openings to adjacent areas. heavy shirt, cuff less trousers, high shoes, and a cap.
FLYING SPARKS AND HOT METAL can
cause injury,
Chipping and grinding cause flying metal. As welds
cool, they can throw off slag.
1.
2.
Wear approved face shield or safety goggles. Side shields
recommended.
Wear proper body protection to protect skin.

CYLINDERS can explode if damaged.
Shielding gas cylinders contain gas under high
pressure. If damaged, a cylinder can explode. Since
gas cylinders are normally part of the welding
process, be sure to treat them carefully.
1. Protect compressed gas cylinders from excessive heat,
mechanical shocks, and arcs.
2. Install and secure cylinders in an upright position by chaining
them to a stationary support or equipment cylinder rack to
prevent falling or tipping.
3. Keep cylinders away from any welding or other electrical
circuits.
4. Never allow a welding electrode to touch any cylinder.
5. Use only correct shielding gas cylinders, regulators, hoses, and
fittings designed for the specific application; maintain them and
associated parts in good condition.
6. Turn face away from valve outlet when opening cylinder valve.
7. Keep protective cap in place over valve except when cylinder is
in use or connected for use.
PRINCIPAL SAFETY STANDARDS
8. Read and follow instructions on compressed gas cylinders,
associated equipment, and CGA publication P-i listed in Safety
Standards.
Safety in Welding and Cutting, ANSI Standard Z49.i, from American Welding Society, 550 N.W. LeJeune Rd, Miami FL 33126
Safetyand Health Standards, OSHA 29 CFR 1910, from Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.
Recommended Safe Practices for the Preparation for Welding and Cuffing of Containers That Have Held Hazardous Substances, American Weld
ing Society Standard AWS F4.i, from American Welding Society, 550 N.W. LeJeune Rd, Miami, FL 33126
National Electrical Code, NFPA Standard 70, from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269.
Safe Handling of Compressed Gases in Cylinders, CGA Pamphlet P-i, from Compressed Gas Association, 1235 Jefferson Davis Highway, Suite
50i, Arlington, VA 22202.
Code for Safety in Welding and Cutting, CSA Standard Wi 17.2, from Canadian Standards Association, Standards Sales, 178 Rexdale Boulevard,
Rexdale, Ontario, Canada M9W 1 R3.
Safe Practices For Occupation And Educational Eye And Face Protection, ANSI Standard Z87. 1, from American National Standards Institute, 1430
Broadway, New York, NY 10018.
Cuffing And Welding Processes, NFPA Standard 51 B, from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269.
SECTION 1 SAFETY INFORMATION 1
SECTION 2 SPECIFICATIONS 1
2-1. Volt-Ampere Curves 2
2-2. Duty Cycle
SECTION 3INSTALLATION 3
3-1. Installing Work Clamp
3-2. Installing Gas Supply
3-3. Gun Polarity Connections 5
34. Installing Drive Rolls And Welding Gun 5
3-5. Connecting Input Power 6
3-6. Installing Wire Spool And Adjusting Hub Tension.... 8
3-7. Threading And Feeding Welding Wire 8
EMF INFORMATION
Considerations About
NOTE ~ Welding And The Effects Of Low Frequency Electric And
Magnetic Fields
The following is a quotation from the General Conclusions Section
of the U.S. Congress, Office of Technology Assessment, Biological
Effects of Power Frequency Electric & Magnetic Fields
Background Paper, OTA-BP-E-53 (Washington, DC: U.S.
Government Printing Office, May 1989): . . there is now a . very
large volume of scientific findings based on experiments at the
cellular level and from studies with animals and people which clearly
establish that low frequency magnetic fields can interact with, and
produce changes in, biological systems. While most of this work is
of very high quality, the results are complex. Current scientific
understanding does not yet allow us to interpret the evidence in a
single coherent framework. Even more frustrating, it does not yet
allow us to draw definite conclusions about questions of possible
risk or to offer clear science-based advice on strategies to minimize
or avoid potential risks.
TABLE OF CONTENTS
2
3
4
To reduce magnetic fields in the workplace, use the following
procedures:
1. Keep cables close together by twisting or taping them.
2. Arrange cables to one side and away from the operator.
3. Do not coil or drape cables around the body.
4. Keep welding power source and cables as far away as
practical.
5. Connect work clamp to workpiece as close to the weld as
possible.
About Pacemakers:
The above procedures are among those also normally
recommended for pacemaker wearers. Consult your doctor for
complete information.
modl 0.1 4/93
SECTION 4-OPERATION 10
SECTION 5 MAINTENANCE & TROUBLESHOOTING 12
5-1. Routine Maintenance 12
5-2. Overload Protection 13
5-3. Wire Drive Assembly Maintenance 14
5-4. Gun Maintenance 15
5-5. Troubleshooting
SECTION 6 ELECTRICAL DIAGRAM 17
SECTION 7 PARTS LIST ia
Figure 7-1. Main Assembly
18
Figure 7-2. MWG-21C Gun 19
Figure 7-3. Baffle w/Cmpts
20
16

6
SECTION 1 SAFETY INFORMATION
Read all safety messages throughout this manual.
U Obey all safety messages to avoid injury.
U Learn the meaning of WARNING and CAUTION.
a WARNING
1 Safety Alert Symbol
modl.1 2/93
1 2
~
!~!~!t ;1~lI~Ie~U
=9 ELECTRIC SHOCK can kIII.f
3
2
a CAUTION
MOVING PARTS can Injure,
2 Signal Word
WARNING means possible death
or serious injury can happen.
CAUTION means possible minor
injury or equipment damage can
S Donottouchliveelectricalparts. ~fl
S Disconnect input power before ~\ installing
Keepawayfrommovingparts.
r Keep all panels and covers closed
happen.
3 Statement Of Hazard And
or servicing. ..4J
when operating.
Result
/ 4 Safety Instructions To Avoid
5 Hazard
READ SAFETY BLOCKS at start of
Section 3-1 before proceeding.
5 Hazard Symbol (If Available)
6 Safety Banner
Read safety blocks for each sym
bol shown.
7H NOTE ~ Turn Off switch when using high frequency. Special instructions for best oper
ation not related to safety.
Type Of Output
Rated Weld Output
Figure 1-1. Safety Information
SECTION 2- SPECIFICATIONS
Table 2-1. Welding Power Source
Specifications Description
Direct Current/Constant Voltage (DC/CV)
200 Amperes, 28 Volts DC, 60% Duty Cycle (See Section 2-2)
Type Of Input Power Single-Phase; 60 Hz; At 200 Or 230 Volts AC
Input Amperes At Rated Output
46 A At 200 V. 40 A At 230 V
Maximum Input Amperes While Idling 1.2 A At 200 V, 1 A At 230 V
KVA/KW Used At Rated Output
Maximum KVA/KW Used While Idling
Max. Open-Circuit Voltage
9.5 kVA/8.3 kW
0.24 kVA/0.17 kW
42 Volts DC
Control Circuit Voltage At Gun 24 Volts DC
Welding Processes Gas Metal Arc (GMAW) And Flux Cored Arc Welding (FCAW)
Calculated Speed Range At No Load 128 To 1051 ipm (3.2 To 266.9 mpm)
7 NOTE
Wire Diameter Range .030 To .045 in (0.8 To 1.1 mm) Flux Cored Wire; .023 To .045 in (0.6 To 1.1 mm) Hard Wire
Overall Dimensions Length: 37 in (940 mm); Width: 19 in (483 mm); Height: 30-1/4 in (768 mm)
Weight
Welding Gun
Rated Output (Air Cooled)
Cable Length 15 ft (4.6 m)
Net: 225 lb (102 kg); Ship: 271 lb (123 kg)
200 Amperes At 60% Duty Cycle Using CO2 Shielding Gas (See Section 2-2)
OM-157 066 Page 1

2-1. Volt-Ampere Curves
2-2. Duty Cycle
The volt-ampere curves show the
50 minimum and maximum voltage
and amperage output capabilities
of the welding power source.
Curves of other settings fall be
tween the curves shown.
0
A~ CAUTION
OUTRTr1
a)
Ui
~ .~..
~
-
~~1~
------H-----
x DurY CYCLE
R~~E
Jo
RAP~E
I I I I I
0 25 50 75 100 125 150 175 200 225
DC AMPERES
Figure 2-1. Volt-Ampere Curves
WELDING LONGER THAN RATED DUTY CYCLE can damage unit or gun and void warranty.
Do n ot weld at rated load longer than shown below.
OM-157 066 Page 2
10
Definition
Duty Cycle is percentage of 10
minutes that unit or gun can
weld at rated load without over
Minutes heating.
Figure 2-2. Duty Cycle
UNIT
60% Duty Cycle At 200 Amperes
g c3
6 Minutes Welding
Chart GUN
6 minutes Welding
GUN
ssbl .110/91 SB-049 424-0
wfwam8.2 8/93
4 Minutes Resting
4 minutes Resting
60% Duty Cycle At 180 Amperes Using Mixed Gas
sbl .38/93 SB-150 215

3-1. Installing Work Clamp
Tools Needed:
~ZZ~ 1/2, 3/4 in
SECTION 3-INSTALLATION
2
1
Figure 3-1. Installing Work Clamp
5
1 Work Cable
2 Boot
Slide boot Onto work cable. Route
cable out front panel opening from
inside.
3 Negative () Output Terminal
Connect cable to terminal and cov
er connection with boot.
4 Hardware
5 WorkClamp
Route cable through clamp handle
and secure to top of clamp with
hardware.
Close door.
Ret. 5T-154 630-A
OM-157 066 Page 3

3-2. Installing Gas Supply
OM-157 066 Page 4
a WARNING
CYLINDERS can explode if damaged.
Keep cylinders away from welding and other
electrical circuits.
Never touch cylinder with welding electrode.
Always secure cylinder to running gear, wall, or
other stationary support.
Figure 3-2. Typical Regulator/Flowmeter Installation
BUILDUP OF SHIELDING GAS can harm
health or kill.
Shut oft shielding gas supply when not in use.
1 Cylinder Bracket
2 S-Hook
Crimp between small hole in brack
et and chain.
3 Chain
4 Snap
2 Crimp onto open end of chain.
Obtain gas cylinder and chain to
running gear.
5 Cap
6 Cylinder Valve
Remove cap, stand to side of
valve, and open valve slightly. Gas
flow blows dust and dirt from valve.
Close valve.
7 Cylinder
8 Regulator/Flowmeter
Install so face is vertical.
9 Gas Hose Connection
Fitting has 5/8-18 right-hand
threads. Obtain and install gas
hose.
10 Flow Adjust
Typical flow rate is 20 cfh (cubic
feet per hour). Check wire man
ufacturers recommended flow
rate.
Make sure flow adjust is closed
when opening cylinder to avoid
damage to the flowmeter.
11 CO2 Adapter
12 0-Ring
Install adapter with 0-ring between
regulator/flowmeter and CO2
cylinder.
Tools Needed:
~ 5/8,1-1/8in
wam4.1 9/91
ssb3.r 5/94 ST-154 623 / ST.158 697-A

3-3. Gun Polarity Connections
4A WARNING
ELECTRIC SHOCK can kill.
Do not touch live electrical parts.
Turn Off welding power source, and disconnect input power before inspecting or installing.
Shown As Shipped Set For Electrode
Positive (DCEP) For Solid Steel Or
Aluminum Wires (GMAW Process).
Wire Drive Assembly Lead
To Positive ( ) Output Terminal
Work Clamp Lead To
Negative () Output Terminal
GUN POLARIfl
CHANGEOVER CONNECTIONS
Reverse Lead Connections For Electrode
Negative (DCEN) For Flux Cored Wires
(FCAW Process). Drive Assembly
Becomes Negative S-144~
5
Figure 3-3. Gun Polarity Connections
3-4. Installing Drive Rolls And Welding Gun
5
Tools Needed:
Figure 3-4. Gun Connections
Swami .1 2/93
1 Polarity Changeover Label
2 Wire Drive Assembly
3 Positive (+) Output Terminal
4 Negative () Output Terminal
Always read and follow wire man
ufacturers recommended polarity.
5 Circuit Breaker CB1 (see
Section 5-2).
Tools Needed:
~ 3/4,11/l6in
1 Pressure Adjustment
2 Pressure Assembly
3 Drive Roll
4 Securing Screw
Ref. ST-153 874-B
Install correct drive roll for wire size
and type using supplied screws.
5 Wire Drive Assembly
6 Gun Securing Knob
7 Gun End
Loosen securing knob. Insert gun
end through opening until it bot
toms against drive assembly.
Tighten knob.
8 Gun Trigger Plug
Insert into receptacle, and tighten
threaded collar.
Close pressure assembly. Close
door.
ST- 154 621 / Ref. ST-154 624-A
OM-157 066 Page 5

3-5. Connecting Input Power
a WARNING
ELECTRIC SHOCK can kill.
Do not touch live electrical parts.
Turn Off welding power source, and disconnect input power before inspecting or installing.
Have only qualified persons install unit.
A. Positioning Jumper Links
~ 3/8 in
Installation must meet National Electrical Code and all other codes.
2
Tools Needed:
OM-157 066 Page 6
200 VOLTS
230 VOLTS
S-153 980
Figure 3-5. Input Voltage Jumper Links Location
Jumper links allow operation on
different input voltages and are
factory set for the highest input
voltage.
Check input voltage available at
site.
1 Input Voltage Label
Look at jumper links and compare
link position with applicable label.
2 Screw
3 Access Door
swam3,1 2/93
To change link position, remove
screw and pivot door up.
4 Input Voltage Jumper Links
Location
Move links to match input voltage.
For example, use 200 volts posi
tion when 200 volts input power is
available.
Close door and secure with screw.
Close side door.
ssb5.1 2/92/ Ret. 5T-154 626-B / Ref. 5T-154 628-B

B. Connecting Input Power
Tools Needed:
Figure 3-6. Input Power Connections
Table 3-1. Electrical Service Requirements*
Have only qualified persons make
this installation.
1 Line Disconnect Device Of
Proper Rating
2 230 Volts AC Wall
Receptacle
3 Input Conductors
4 Grounding Conductor
Select size and length using
Table 3-1. Conductor rating must
comply with national, state, and
local electrical codes.
Install and connect grounding
conductor and input conductors in
conduit or equivalent between wall
receptacle and deenergized line
disconnect device.
Connect grounding conductor first,
then line input conductors.
Be sure grounding conductor goes
to an earth ground.
5 Overcurrent Protection
Select type and size using
Table 3-1. Install into deenergized
line disconnect device (fused dis
connect switch shown).
6 Input Power Plug
Turn off unit Power switch, and
connect plug to wall receptacle.
ssb2.2 12/94 Ret. 5T-154 619-B I Ret. ST-149 405-B
Input Voltage 200 230
Input Amperes At Rated Output 46 40
Recommended Standard Fuse Or Circuit Breaker Rating In Amperes 70 60
Mm Input Conductor Size In AWGIKcmiI 8 8
Max Input Conductor Length In Feet (Meters) 89(27) 117 (36)
Mm Grounding Conductor Size In AWGIKcmiI 8 10
These values are calculated from the 1993 edition of the National Electrical Code (NEC). S-0092-H
5
3
OM-157 066 Page 7

3-6. Installing Wire Spool And Adjusting Hub Tension
Figure 3-7. Installing Wire Spool And Adjusting Hub Tension
3-7. Threading And Feeding Welding Wire
OM-157 066 Page 8
a WARNING
CYLINDERS can explode if damaged.
Keep cylinders away from welding and other
electrical circuits.
Never touch cylinder with welding electrode.
Always secure cylinder to running gear, wall, or
other stationary support.
ELECTRIC SHOCK can kill.
Do not touch live electrical parts.
The welding wire, drive rolls, drive assembly, and all
metal parts touching the welding wire are electrically
live when welding or feeding wire using gun trigger.
Turn Off unit.
1 Wire Spool
2 Gun Contact lip
If necessary, cut welding wire off at
contact tip, and retract wire onto
spool and secure.
3 Retaining Ring
4 Compression Spring
Remove ring and pull off spool.
Compression spring is used with 8
in (200 mm) spools.
5 Hub
6 Hub Pin
Slide spool onto hub so wire feeds
off bottom. Turn spool until hub pin
fits hole in back of spool. Reinstall
retaining ring.
7 Hub Tension Nut
Grasp spool in one hand and turn
while using a wrench to adjust hub
tension nut. When a slight force is
needed to turn spool, tension is
set.
Thread welding wire (see Section
3-7). Close door.
Tools Needed:
WELDING WIRE can cause puncture
wounds.
Do not press gun trigger until instructed to do so.
Do not point gun toward any part of the body, other
people, or any metal when threading welding wire.
HOT SURFACES can burn skin.
Allow gun to cool before touching.
Z~ 15/16 in
Ref. ST-154 626-B / Ref. ST-072 573-B
swarn5.1 10/91 /swarn2.1 9/91

Close and tighten pressure assembly,
and let go of wire.
/
Press gun trigger until wire
comes out of gun. Reinstall
contact tip and nozzle.
-~
Hold wire tightly to keep it
from unraveling.
Remove gun nozzle
and contact tip.
Feed wire to check drive roll pressure.
Tighten knob enough to prevent slipping.
Figure 3-8. Threading And Feeding Welding Wire
1 Wire Spool
2 Welding Wire
3 Inlet Wire Guide
4 Pressure Adjustment Knob
5 Pressure Assembly
6 Drive Roll
7 Outlet Wire Guide
8 Gun Conduit Cable
Lay gun cable out straight.
Open pressure assembly. Pull and hold wire; cut off end. Push wire thru guides into gun;
continue to hold wire.
-~ =~
ION
POWER =
OOF~
Set switch.
6
Cut off wire.
Close and latch door.
ST-800 739-A / ST.154 251 / S-0627-A
OM-157 066 Page 9

OM-157 066 Page 10
a WARNING
ELECTRIC SHOCK can kill.
Always wear dry insulating gloves.
SECTION 4- OPERATION
Insulate yourself from work and ground.
Do not touch live electrical parts.
Keep all panels and covers securely in place
FUMES AND GASES can be hazardous
to your health.
Keep your head out of the fumes.
Ventilate area, or use breathing device.
Read Material Safety Data Sheets (MSDS5) and
manufacturers instructions for material used.
WELDING can cause fire or explosion.
Do not weld near flammable material.
Watch for fire; keep extinguisher nearby.
Do not locate unit over combustible surfaces.
Do not weld on closed containers.
Allow work and equipment to cool before handling
ARCING can damage switch.
Do not change Voltage switch position while
welding.
Arcing inside switch can damage contacts, causing
switch to fail.
~ ~
P
,..~
~
~
-
~
ARC RAYS can burn eyes and skin;
NOISE can damage hearing.
Wear welding helmet with correct shade of filter.
S Wear correct eye, ear, and body protection.
MOVING PARTS can cause injury.
Keep away from pinch points such as drive rolls.
Keep all doors, panels, covers, and guards closed
and securely in place.
MAGNETIC FIELDS FROM HIGH CUR
RENTS can affect pacemaker operation.
Pacemaker wearers keep away.
Wearers should consult their doctor before going
near arc welding, gouging, or spot welding opera
tions.
WELDING CURRENT can damage elec
tronic parts in vehicles.
Disconnect both battery cables before welding on a
vehicle.
Place work clamp as close to the weld as possible.
See Safety Precautions at beginning of manual for ba
sic welding safety information. swam6.2 8/92
Wear the following while
2 welding:
3
1 Dry, Insulating Gloves
/
Figure 4-1. Safety Equipment
Figure 4-2. Center Baffle Controls
2 Safety Glasses With Side
Shields
3 Welding Helmet With Correct
Shade Of Filter (See ANSI
Z49.1)
1 Wire Mode Switch
sb3.1 1/94
For better control of wire speed use
Low position when wire speed is
between 90 and 670 ipm. Use Full
position when wire speed is be
tween 150 ipm and 1030 ipm.
2 Voltage Range Selector
Place switch in desired position.
See inside rear cover for settings.
Ret. ST-153 874-B / S-171 601

Tools Needed:
Figure 4-3. Front Panel Controls
1 Wire Speed Control
Use control to set wire teed speed.
2 Voltage Control
Use control and Voltage Range
Selector (see Figure 4-2) to set arc
voltage. Step 6 ot Low range and
Step 1 ot High range overlap.
4 Power Switch
Use switch to turn unit On and Ott.
The pilot light comes on when unit
is turned on.
Use wire brush or sandpaper to
clean metal at weld joint area.
Connect work clamp to clean,
paint-tree location on workpiece,
as close as possible to weld area.
Ref. 5T-154 622-B / 5T-171 639/ Ref. ST-154 251
OM-157 066 Page 11

SECTION 5- MAINTENANCE & TROUBLESHOOTING
a WARNING
ELECTRIC SHOCK can kill.
Do not touch live electrical parts.
Turn Ofl welding power source, and disconnect
input power before inspecting, maintaining, or
servicing.
HOT PARTS can cause severe burns.
Allow cooling period before maintaining or
servicing.
5-1. Routine Maintenance
Turn Off all power before maintaining.
Each Spool Of Wire
See
Section I
5.4
________
Blow Out
Gun
Casing
~Clean
Nozzle
And Check
Contact lip
OM-157 066 Page 12
7
_
0
4f
-~ 3 Months
W~N~
Replace
Unreadable
Labels
Clean
~ lighten
3-1 Terminals
~Replace ~9
Parts
14-Pin Cord
Gas Hose Gun Cable
Figure 5-1. Maintenance Schedule
MOVING PARTS can cause injury.
Keep away from moving parts.
Keep away from pinch points such as drive rolls.
Maintenance and troubleshooting to be performed
only by qualified persons. swarnS 2 2/93
3-4
-~ 6 Months
Blow Out
Or
Vacuum
Inside
During Heavy Service,
Clean Monthly
Clean
Drive
Rolls

5-2. Overload Protection
a WARNING
A. Circuit Breaker CB1
B. Fuses Fl And F2
C. Overheating
Figure 5-2. Circuit Breaker CB1
Figure 5-3. Fuse Location
Figure 5-4. Overheating
READ SAFETY BLOCKS at start of
Section 5 before proceeding.
1 Circuit Breaker CB1
If CB1 opens, wire feed stops.
Check gun liner for blockage or
kinks, and check for jammed wire,
binding drive gear, or misaligned
drive rolls. Allow a cooling period
before resetting CB1.
Turn Off unit and disconnect input
power.
1 Fuse Fl (See Parts List For
Rating)
Fl protects the 115 volts ac wind
ing of transformer Ti. If Fl opens,
all weld output stops and pilot light
PL1 goes out.
2 Fuse F2 (See Parts List For
Rating)
F2 protects the 24 volts ac winding
of transformer Ti. If F2 opens, all
weld output stops.
Ret. ST-153 874-B
Ret. ST-800 928-B
OM-157 066 Page 13

5-3. Wire Drive Assembly Maintenance
Tools Needed:
OM-157 066 Page 14
Figure 5-5. Wire Drive Assembly Maintenance
READ SAFETY BLOCKS at start of
Section 5 before proceeding.
Turn Off unit and disconnect input
power.
1 Wire Spool
2 Gun Contact lip
Cut welding wire off at contact tip.
Retract wire onto spool and se
cure.
3 Drive Roll Alignment Bolt
Turn in or out until groove lines up
with wire guide.
4 Drive Roll
5 Wire Inlet Guide
Remove guide by pressing on
barbed area or cutting off one end
near housing and pulling it out of
hole. Push new guide into hole
from rear until it snaps in place.
6 Pressure Roll Arm
7 Cotter Pin
8 Pin
9 Screw
10 Bearing
Remove bearing as shown. Install
new bearing and secure with
screw. Reinstall arm onto pin and
secure with cotter pin.
Thread welding wire (see Section
3-7). Close door.
Ret. ST-154 626-B / SA-145 763 / ST-i 54633

5-4. Gun Maintenance
a WARNING
Head Tube
FLYING METAL CHIPS AND DIRT can cause injury and damage equipment.
S Point gun away from people and in a safe direction when blowing out with compressed air.
I
Remove nozzle,
contact tip, and
liner collet.
/
Remove liner.
Figure 5-6. Gun Maintenance
READ SAFETY BLOCKS at start of
Section 5 before proceeding.
//
II /
f
/
swarnlo.1 10/91
Turn Off unit and disconnect input
power.
1 Wire Spool
Cut welding wire off at contact tip.
Retract wire onto spool and se
cure.
2 Gun Securing Knob
Loosen knob and remove gun and
trigger plug.
Reassemble gun.
To Reassemble Gun:
Install contact tip.
Insert new liner.
Install collet onto liner and tighten
into gun/feeder connector using
wrench.
Cut liner off near collet so that liner
end is as close to drive rolls as pos
sible without touching.
Install nozzle.
Reinstall gun (see Section 3.4).
Thread welding wire (see Section
3-7). Close door.
Gun/Feeder
Connector
Tools Needed:
~ 3/8in
out
gun casin
Ret. ST-154 624-A/ ST-801 149
OM-157 066 Page 15

5-5. Troubleshooting
a WARNING
Welding Trouble
No weld output; wire does not feed.
No weld output; wire does not feed; fan i -.
motor continues to run and pilot light is
off.
No weld output; wire feeds.
Low weld output.
Wire Drive/Gun Trouble
Electrode wire feeding stops during i -.
welding. I
OM-157 066 Page 16
READ SAFETY BLOCKS at start of
Sectio n 5 before
proceeding.
Remedy
Secure power cord plug in receptacle.
Reset circuit breaker CB1. Replace fuse Fl and/or F2.
Replace building line fuse or reset circuit breaker if open
Secure gun trigger plug in receptacle or repair leads, or replace
trigger switch.
Thermostat open (overheating). Allow tan to run; the thermostat
will close when the unit has cooled.
Connect work clamp to get good metal to metal contact.
Replace contact tip.
1 -~
Section
-a 3-5
-a 5-2
-~ 3-5
-~ 3-4
]-..,
5-2
Figure 4-3
- Connect unit to proper input voltage or check for low line volt~~j - ~ I
Straighten gun cable and/or replace damaged parts.
Adjust hub tension.
Adjust drive roll pressure.
Replace contact tip if blocked.
Clean or replace wire inlet guide or liner if dirty or plugged.
Replace drive roll or pressure bearing if worn or slipping.
Secure gun trigger plug in receptacle or repair leads, or replace
trigger switch.
Check and replace Fl and/or F2.
Check and clear any restrictions at drive assembly and liner.
Have nearest Factory Authorized Service Station check drive
motor.
5-4
-~ 5-4
-~ 3-6
-~ 3-7
-a
-a
5-4
5-3, 5-4
5-3
3-4
-~ 5-2
-a 5-3, 5-4
-a
-

P4G20 S1A
SECTION 6- ELECTRICAL DIAGRAM
,., ,.,
~3/P.G3
e4/R.c4
~5/RG5
Figure 6-1. Circuit Diagram For Welding Power Source
I;~
cc~~~ 1 2
, ~ ~
U~ In .
A-A-A
9 y ~ RC3~l3>)___~~?-> 4
l~:3-3 >>~-~~< ~
~3-2>) I
~3-9>>
~3-15>>-
FS~3-I~> <
LRrvt
OM-157 066 Page 17
3
I~l
SB-173 544-B

7-3
Fig
0 (71 0 0) 0) -u CD CD
7
3
2
Cl)m C, 0z -ICl) I -I
6
13
)
14
K
I
23
7-2
Fig
19
20
21
22
073-B
ST-157
Assembly
Main
7-1.
Figure

Parts For Main Assembly
NOTE: All items indented by a dot(s) are included with the item listed directly above.
Item Part
No. No. Description
1 146168
2 083 526
009 418
3 072 802
009419
4 Fig 7-3
5 171 658
6 171 213
7
148 808
150783
049 399
116996
605 227
134 834
149 332
152742
048420
037 957
037 956
605 886
605 884
171 600
026 947
2
3
included w/ltem 7
Enclosure Panel
Housing Rcpt & Sockets
Terminal, female
Housing Plug & Pins
Terminal, male
Baffle w/Cmpts
Transformer
Stabilizer
Rear Panel w/Cmpts
Fan Motor
Fan Blade
Speed Nut
Gas Valve
Nylon Nut, .750
Hose
Hose Clamp
Rectifier
. Capacitor
Diode, RP
. Diode,
. Washer,
. Half
. Thermostat,
SP
.750
Nut, .750-16
NC
. Stand-Off
4
6
7
Item Part
No. No. Description
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
152862
009 970
143810
169654
044426
602 387
146 165
089 899
146 167
134464
+170 513
047 721
146 161
135 390
070799
121 614
091 685
605 741
008 999
027 645
035 897
097 924
048 282
12
Grommet
Rectifier Bracket
Rear Panel
Tank Bracket Support
Cable Clamp
Cylinder Chain
Side Panel, LH
Latch
Side Panel
Warning Label
Wrapper
Cord Set
Base
Axle
Wheel
Retaining Ring
Resistor
Clip
Caster
Front Panel w/Cmpts
Light
Potentiometer
2
Knob
Receptacle w/Sockets
15
14
Ref. ST-801 148
Figure 7-2. MWG-23B
I Item Part
] No. No. Description
079 534 .
128 755 .
153 197 .
148 956 .
. Terminal, female
Switch, DPST
Selector Switch
Switch Handle
175 060 Front Panel
155 418 Front Control Panel
171 639 Control Plate
174 840 . Nameplate
144 127 . Cover, module opening
057 357 . Bushing, 1 .l25mtg
143974 Handle
23 175 127 MWG-23B Gun, (Fig 7.2)
144 548 Consumables Label
113 280 Gas Hose
600 318 Weld Cable
130 750 Ground Clamp
039 778 Receptacle, 50A 250V
121 580 Regulator/Flowmeter
028 509 Adapter/Regulator
+When ordering a component originally dis
playing a precautionary label, the label should
also be ordered.
Be sure to provide Model and Serial Number
when ordering replacement parts.
Item Part
No. No. Description
1 110 793 Handle Assembly
2 110780 Nut,MlOxl
3 175180 HeadTube
4 175177 Diffusor
5 175 175 Holder, tip recessed
5 175 176 Holder, tip flush
6 175 230 Contact Tip, .025 (lOpk)
6 175 231 Contact Tip, .030 (lOpk)
6 175 232 Contact Tip, .035 (lOpk)
6 175 233 Contact Tip, .045 (lOpk)
7 175 234 Nozzle, std 1/2 in (2pk)
7 175 235 Nozzle, hd 1/2 in (2pk)
7 175 236 Nozzle, small 3/8 in (2pk)
7 175 237 Nozzle, spot weld (2pk)
8 110 794 Trigger Switch Assembly
9 080 565 Terminal
10 175 179 Cable Assembly, l5ft
11 110797 Sleeve,rubber
12 175 178 Liner, .035045
13 120715 .
Collet, .035045
12 175253 Liner, .023035
13 110784 .
Collet, .023035
14 079974 0-Ring
15 110 796 Connector, gun/feeder
16 079 878 Connector & Pins
079 535 .
Pins
17 048 834 Clamp
OPTIONAL
OM-157 066 Page 19

12
NOTE: All items indented by a dot(s) are included with the item listed directly above.
127 232 Drive Assembly
1 092 237 .
Knob
2 089477 Spring
3 085244 CuppedWasher
4 089 562 Fastener
5 010 224 Spring Pin
6 090 416 Hinge Pin
7 124 817 Drive Housing
8 124 778 T-Knob
9 151 828 Cotter Hair Pin
10 112031 PressureLever
11 111 523 Bearing
12 124 818 Drive Roll, combination
12 087 130 Drive Roll, .023
13 092865 Key
14 124 820 Hub, drive roll
15 079 625 Spring Washer
16 605 308 Retaining Ring
17 021 469 Danger Label
18 144 933 Access Door
19 058 549 Wire Guide, 1/16
19 056 193 Wire Guide, .023.045
OM-157 066 Page 20
6
6
27
Figure 7-3. Baffle w/Cmpts (Fig 7-1 Item 4)
Item Part Item Part Item Part
No. No. Description No. No. Description No. No. Description
20 130 365 Insulator
21 122741 Motor
22 175775 Motor Bracket
23 174812 Baffle
24 148 956 Switch Handle
25 011 609 Toggle Switch, SPDT
26 083 431 Circuit Breaker
27 058 427 Retaining Ring
28 085980 Nut
29 605 941 Flat Washer
30 057 543 Spring, .845 OD
31 057971 Keyed Washer
32 010191 FiberWasher
33 058 628 Brake Washer
34 057 745 Spring, 2.430 OD
35 058 428 Hub, spool
36 177307 Support Reel
37 083 147 Grommet
38 082 902 Strip, mtg center
39 092 186 Strip, mtg LH & RH
40 156 517 Capacitor
41 114 780 Contactor
34
114786 Link
42 134 201 PC Card Stand-Oft
43 173 002 Motor Speed Control Card
44 012 658 .
44 073 426 .
Fuse,
Fuse,
mintr gI slo-blo
2A 125V
mintr gI slo-blo
5A 125V
165896 Connector & Sockets
135558 Connector & Sockets
165 745 Connector & Sockets
079 747 .
Connector, rect skt
45 171 610 Selector Switch
46 153 322 Terminal Assembly, pri 2V
038618 .Link
47 010199 Tubing
48 039 047 Output Terminal, red
49 039 046 Output Terminal, black
50 071 971 Cover
OPTIONAL
45
Recommended Spare Parts
40
ST-801 104-A
Be sure to provide Model and Serial Number
when ordering replacement parts.