Lincoln Electric MULTI-WELD SVM151-A User manual

SVM151-A
September, 2002
Safety Depends onYou
Lincoln arc welding and cutting
equipment is designed and built
with safety in mind. However,
your overall safety can be in-
creased by proper installation . . .
and thoughtful operation on
your part. DO NOT INSTALL,
OPERATE OR REPAIR THIS
EQUIPMENT WITHOUT
READING THIS MANUAL AND
THE SAFETY PRECAUTIONS
CONTAINED THROUGHOUT.
And, most importantly, think
before you act and be careful.
SERVICE MANUAL
For use with machines having Code Numbers: 10645
10736
Multi-Weld 350 Arc Converter
TM
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• Sales and Service through Subsidiaries and Distributors Worldwide •
Cleveland, Ohio 44117-1199 U.S.A. TEL: [phone] FAX: [phone] WEB SITE: www.lincolnelectric.com
• World's Leader in Welding and Cutting Products •
Copyright © 2000 Lincoln Global Inc.

i i
SAFETY
FOR ENGINE
powered equipment.
1.a. Turn the engine off before troubleshooting and maintenance
work unless the maintenance work requires it to be running.
____________________________________________________
1.b.Operate engines in open, well-ventilated
areas or vent the engine exhaust fumes
outdoors.
____________________________________________________
1.c. Do not add the fuel near an open flame weld-
ing arc or when the engine is running. Stop
the engine and allow it to cool before refuel-
ing to prevent spilled fuel from vaporizing on
contact with hot engine parts and igniting. Do
not spill fuel when filling tank. If fuel is spilled,
wipe it up and do not start engine until fumes
have been eliminated.
____________________________________________________
1.d. Keep all equipment safety guards, covers
and devices in position and in good
repair.Keep hands, hair, clothing and tools
away from V-belts, gears, fans and all other
moving parts when starting, operating or
repairing equipment.
____________________________________________________
1.e. In some cases it may be necessary to remove safety
guards to perform required maintenance. Remove
guards only when necessary and replace them when the
maintenance requiring their removal is complete.
Always use the greatest care when working near moving
parts.
___________________________________________________
1.f. Do not put your hands near the engine fan. Do not attempt to
override the governor or idler by pushing on the throttle con-
trol rods while the engine is running.
___________________________________________________
1.g. To prevent accidentally starting gasoline engines while
turning the engine or welding generator during maintenance
work, disconnect the spark plug wires, distributor cap or
magneto wire as appropriate.
ARC WELDING can be hazardous. PROTECT YOURSELF AND OTHERS FROM POSSIBLE SERIOUS INJURY OR DEATH.
KEEP CHILDREN AWAY. PACEMAKER WEARERS SHOULD CONSULT WITH THEIR DOCTOR BEFORE OPERATING.
Read and understand the following safety highlights. For additional safety information, it is strongly recommended that you
purchase a copy of “Safety in Welding & Cutting -ANSI Standard Z49.1” from theAmerican 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.
WARNING
Mar ‘95
ELECTRIC AND
MAGNETIC FIELDS
may be dangerous
2.a. Electric current flowing through any conductor causes
localized Electric and Magnetic Fields (EMF). Welding
current creates EMF fields around welding cables and
welding machines
2.b. EMF fields may interfere with some pacemakers, and
welders having a pacemaker should consult their physician
before welding.
2.c. Exposure to EMF fields in welding may have other health
effects which are now not known.
2.d. All welders should use the following procedures in order to
minimize exposure to EMF fields from the welding circuit:
2.d.1. Route the electrode and work cables together - Secure
them with tape when possible.
2.d.2. Never coil the electrode lead around your body.
2.d.3. Do not place your body between the electrode and
work cables. If the electrode cable is on your right
side, the work cable should also be on your right side.
2.d.4. Connect the work cable to the workpiece as close as
possible to the area being welded.
2.d.5. Do not work next to welding power source.
1.h. To avoid scalding, do not remove the
radiator pressure cap when the engine is
hot.
CALIFORNIA PROPOSITION 65 WARNINGS
Diesel engine exhaust and some of its constituents
are known to the State of California to cause can-
cer, birth defects, and other reproductive harm.
The engine exhaust from this product contains
chemicals known to the State of California to cause
cancer, birth defects, or other reproductive harm.
The Above For Diesel Engines The Above For Gasoline Engines
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ii ii
SAFETY
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ARC RAYS can burn.
4.a. Use a shield with the proper filter and cover
plates to protect your eyes from sparks and
the rays of the arc when welding or observing
open arc welding. Headshield and filter lens
should conform to ANSI Z87. I standards.
4.b. Use suitable clothing made from durable flame-resistant
material to protect your skin and that of your helpers from
the arc rays.
4.c. Protect other nearby personnel with suitable, non-flammable
screening and/or warn them not to watch the arc nor expose
themselves to the arc rays or to hot spatter or metal.
ELECTRIC SHOCK can kill.
3.a. The electrode and work (or ground) circuits
are electrically “hot” when the welder is on.
Do not touch these “hot” parts with your bare
skin or wet clothing. Wear dry, hole-free
gloves to insulate hands.
3.b. Insulate yourself from work and ground using dry insulation.
Make certain the insulation is large enough to cover your full
area of physical contact with work and ground.
In addition to the normal safety precautions, if welding
must be performed under electrically hazardous
conditions (in damp locations or while wearing wet
clothing; on metal structures such as floors, gratings or
scaffolds; when in cramped positions such as sitting,
kneeling or lying, if there is a high risk of unavoidable or
accidental contact with the workpiece or ground) use
the following equipment:
• Semiautomatic DC Constant Voltage (Wire) Welder.
• DC Manual (Stick) Welder.
• AC Welder with Reduced Voltage Control.
3.c. In semiautomatic or automatic wire welding, the electrode,
electrode reel, welding head, nozzle or semiautomatic
welding gun are also electrically “hot”.
3.d. Always be sure the work cable makes a good electrical
connection with the metal being welded. The connection
should be as close as possible to the area being welded.
3.e. Ground the work or metal to be welded to a good electrical
(earth) ground.
3.f.
Maintain the electrode holder, work clamp, welding cable and
welding machine in good, safe operating condition. Replace
damaged insulation.
3.g. Never dip the electrode in water for cooling.
3.h. Never simultaneously touch electrically “hot” parts of
electrode holders connected to two welders because voltage
between the two can be the total of the open circuit voltage
of both welders.
3.i. When working above floor level, use a safety belt to protect
yourself from a fall should you get a shock.
3.j. Also see Items 6.c. and 8.
FUMES AND GASES
can be dangerous.
5.a.Welding may produce fumes and gases
hazardous to health. Avoid breathing these
fumes and gases.When welding, keep
your head out of the fume. Use enough
ventilation and/or exhaust at the arc to keep
fumes and gases away from the breathing zone. When
welding with electrodes which require special
ventilation such as stainless or hard facing (see
instructions on container or MSDS) or on lead or
cadmium plated steel and other metals or coatings
which produce highly toxic fumes, keep exposure as
low as possible and below Threshold Limit Values (TLV)
using local exhaust or mechanical ventilation. In
confined spaces or in some circumstances, outdoors, a
respirator may be required. Additional precautions are
also required when welding on galvanized steel.
5.b.
Do not weld in locations near chlorinated hydrocarbon vapors
coming from degreasing, cleaning or spraying operations.
The heat and rays of the arc can react with solvent vapors
to
form phosgene, a highly toxic gas, and other irritating
products.
5.c. Shielding gases used for arc welding can displace air and
cause injury or death. Always use enough ventilation,
especially in confined areas, to insure breathing air is safe.
5.d. Read and understand the manufacturer’s instructions for this
equipment and the consumables to be used, including the
material safety data sheet (MSDS) and follow your
employer’s safety practices. MSDS forms are available from
your welding distributor or from the manufacturer.
5.e. Also see item 1.b. Mar ‘95

iii iii
SAFETY
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FOR ELECTRICALLY
powered equipment.
8.a. Turn off input power using the disconnect
switch at the fuse box before working on
the equipment.
8.b. Install equipment in accordance with the U.S. National
Electrical Code, all local codes and the manufacturer’s
recommendations.
8.c. Ground the equipment in accordance with the U.S. National
Electrical Code and the manufacturer’s recommendations.
CYLINDER may explode
if damaged.
7.a. Use only compressed gas cylinders
containing the correct shielding gas for the
process used and properly operating
regulators designed for the gas and
pressure used. All hoses, fittings, etc. should be suitable for
the application and maintained in good condition.
7.b. Always keep cylinders in an upright position securely
chained to an undercarriage or fixed support.
7.c. Cylinders should be located:
•Away from areas where they may be struck or subjected to
physical damage.
•A safe distance from arc welding or cutting operations and
any other source of heat, sparks, or flame.
7.d. Never allow the electrode, electrode holder or any other
electrically “hot” parts to touch a cylinder.
7.e. Keep your head and face away from the cylinder valve outlet
when opening the cylinder valve.
7.f. Valve protection caps should always be in place and hand
tight except when the cylinder is in use or connected for
use.
7.g. Read and follow the instructions on compressed gas
cylinders, associated equipment, and CGA publication P-l,
“Precautions for Safe Handling of Compressed Gases in
Cylinders,” available from the Compressed Gas Association
1235 Jefferson Davis Highway, Arlington, VA 22202.
Mar ‘95
WELDING SPARKS can
cause fire or explosion.
6.a. Remove fire hazards from the welding area.
If this is not possible, cover them to prevent
the welding sparks from starting a fire.
Remember that welding sparks and hot
materials from welding can easily go through small cracks
and openings to adjacent areas. Avoid welding near
hydraulic lines. Have a fire extinguisher readily available.
6.b. Where compressed gases are to be used at the job site,
special precautions should be used to prevent hazardous
situations. Refer to “Safety in Welding and Cutting” (ANSI
Standard Z49.1) and the operating information for the
equipment being used.
6.c. When not welding, make certain no part of the electrode
circuit is touching the work or ground. Accidental contact can
cause overheating and create a fire hazard.
6.d. Do not heat, cut or weld tanks, drums or containers until the
proper steps have been taken to insure that such procedures
will not cause flammable or toxic vapors from substances
inside. They can cause an explosion even though they have
been “cleaned”. For information, purchase “Recommended
Safe Practices for the
Preparation for Welding and Cutting of
Containers and Piping That Have Held Hazardous
Substances”, AWS F4.1 from the American Welding Society
(see address above).
6.e. Vent hollow castings or containers before heating, cutting or
welding. They may explode.
6.f.
Sparks and spatter are thrown from the welding arc. Wear oil
free protective garments such as leather gloves, heavy shirt,
cuffless trousers, high shoes and a cap over your hair. Wear
ear plugs when welding out of position or in confined places.
Always wear safety glasses with side shields when in a
welding area.
6.g. Connect the work cable to the work as close to the welding
area as practical. Work cables connected to the building
framework or other locations away from the welding area
increase the possibility of the welding current passing
through lifting chains, crane cables or other alternate circuits.
This can create fire hazards or overheat lifting chains or
cables until they fail.
6.h. Also see item 1.c.

iv iv
SAFETY
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PRÉCAUTIONS DE SÛRETÉ
Pour votre propre protection lire et observer toutes les instructions
et les précautions de sûreté specifiques qui parraissent dans ce
manuel aussi bien que les précautions de sûreté générales suiv-
antes:
Sûreté Pour Soudage A L’Arc
1. Protegez-vous contre la secousse électrique:
a. Les circuits à l’électrode et à la piéce sont sous tension
quand la machine à souder est en marche. Eviter toujours
tout contact entre les parties sous tension et la peau nue
ou les vétements mouillés. Porter des gants secs et sans
trous pour isoler les mains.
b. Faire trés attention de bien s’isoler de la masse quand on
soude dans des endroits humides, ou sur un plancher
metallique ou des grilles metalliques, principalement dans
les positions assis ou couché pour lesquelles une
grande partie du corps peut être en contact avec la
masse.
c. Maintenir le porte-électrode, la pince de masse, le câble
de soudage et la machine à souder en bon et sûr état
defonctionnement.
d. Ne jamais plonger le porte-électrode dans l’eau pour le
refroidir.
e. Ne jamais toucher simultanément les parties sous tension
des porte-électrodes connectés à deux machines à soud-
er parce que la tension entre les deux pinces peut être le
total de la tension à vide des deux machines.
f. Si on utilise la machine à souder comme une source de
courant pour soudage semi-automatique, ces precautions
pour le porte-électrode s’applicuent aussi au pistolet de
soudage.
2. Dans le cas de travail au dessus du niveau du sol, se pro-
téger 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-inflamma-
bles.
4. Des gouttes de laitier en fusion sont émises de l’arc de
soudage. Se protéger avec des vêtements de protection
libres de l’huile, tels que les gants en cuir, chemise épaisse,
pantalons sans revers, et chaussures montantes.
5. Toujours porter des lunettes de sécurité dans la zone de
soudage. Utiliser des lunettes avec écrans lateraux dans les
zones où l’on pique le laitier.
6. Eloigner les matériaux inflammables ou les recouvrir afin de
prévenir tout risque d’incendie dû aux étincelles.
7. Quand on ne soude pas, poser la pince à une endroit isolé
de la masse. Un court-circuit accidental peut provoquer un
échauffement et un risque d’incendie.
8. S’assurer que la masse est connectée le plus prés possible
de la zone de travail qu’il est pratique de le faire. Si on place
la masse sur la charpente de la construction ou d’autres
endroits éloignés de la zone de travail, on augmente le risque
de voir passer le courant de soudage par les chaines de lev-
age, câbles de grue, ou autres circuits. Cela peut provoquer
des risques d’incendie ou d’echauffement des chaines et des
câbles jusqu’à ce qu’ils se rompent.
9. Assurer une ventilation suffisante dans la zone de soudage.
Ceci est particuliérement important pour le soudage de tôles
galvanisées plombées, ou cadmiées ou tout autre métal qui
produit des fumeés toxiques.
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 forte-
ment toxique) ou autres produits irritants.
11. Pour obtenir de plus amples renseignements sur la sûreté,
voir le code “Code for safety in welding and cutting” CSA
Standard W 117.2-1974.
PRÉCAUTIONS DE SÛRETÉ POUR
LES MACHINES À SOUDER À
TRANSFORMATEUR ET À
REDRESSEUR
1. Relier à la terre le chassis du poste conformement au code
de l’électricité et aux recommendations du fabricant. Le dis-
positif 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.
Mar. ‘93

v v
- MASTER TABLE OF CONTENTS FOR ALL SECTIONS -
MULTI-WELD 350
Page
Safety.................................................................................................................................................i-iv
Installation.............................................................................................................................Section A
Operation...............................................................................................................................Section B
Accessories ..........................................................................................................................Section C
Maintenance..........................................................................................................................Section D
Theory of Operation .............................................................................................................Section E
Troubleshooting and Repair................................................................................................Section F
Electrical Diagrams..............................................................................................................Section G
Parts Manual......................................................................................................................P361 Series
RETURN TO MAIN INDEX

Installation.............................................................................................................................Section A
Technical Specifications..............................................................................................................A-2
Safety Precautions......................................................................................................................A-3
Quick-Connect “Pig-Tails” ...........................................................................................................A-3
Attachment and Arrangement of “Pig-Tails”................................................................................A-3
Work Connection.........................................................................................................................A-4
Case Grounding..........................................................................................................................A-4
Inter-Connection of Converters...................................................................................................A-4
Power Source Setup...................................................................................................................A-6
Section A-1 Section A-1
TABLE OF CONTENTS
- INSTALLATION SECTION -
MULTI-WELD 350
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A-2 A-2
INSTALLATION
MULTI-WELD 350
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ELECTRICAL SPECIFICATIONS
Amps (DC+) Volts (DC+)
Output Rating @ 50°C (122°F) 350 34
Input Rating @ 50°C (122°F) 165 80
Max. Input Range 50-113 (Peak)
Max. O.C.V. 78
Output Preset Range 30-350 15-40
PHYSICAL DIMENSIONS
Height Width Depth Net Weight
11.6 in. 10.0 in. 21.5 in. 59.5 lbs.
295 mm 254 mm 546 mm 27.0 kg.
TEMPERATURE RANGES
Operating Temperature Range Storage Temperature Range
-40 to +122°F -40 to +185°F
-20 to +50°C -40 to +85°C
TECHNICAL SPECIFICATIONS - MULTI-WELD 350 (K1735-1)

Read this entire installation section before you
start installation.
SAFETY PRECAUTIONS
ELECTRIC SHOCK can kill.
• Do not touch electrically live
parts or electrodes with your
skin or wet clothing.
• Insulate yourself from the
work and ground.
• Always wear dry insulating
gloves.
Only qualified personnel should install, use, or ser-
vice this equipment.
QUICK-CONNECT “PIG-TAILS”
The Multi-Weld 350 is factory provided with two 21
in.(53 cm) long 2/0 AWG (70 mm2) “pig-tail” cables.
Their 0.5" (13 mm) hole lug ends are routed through
the “INPUT +” (on back) and “ELECTRODE +” (on
front) cable channels of the Converter. They are
attached to the bottom-accessed covered cable con-
nection studs.
Attach the preferred standard, user-provided Quick-
connect terminal (such as Lincoln Twist-Mate or Tweco
2-MPC type) to the cut-off end of these cables. Use the
female connector on the “ELECTRODE +” cable and
the male connector on the “INPUT +” cable.
ATTACHMENT AND
ARRANGEMENT OF “PIG-TAILS”
To best suit the desired inter-connection of the
Converters, the “pig-tail” cables may be routed into the
front or back cable channels. For single or double “pig-
tail” cables, route through the bottom-accessed cov-
ered cable connection studs. (See Figures A.1
and B.1.)
To connect the “pig-tail” cables to the Converter:
1. Stand the Converter vertically on its rear handle
and skid to gain access to the bottom stud covers.
Then remove the two 0.25"(6.3 mm) screws secur-
ing each cover and fold out the cover insulation.
2. Route the appropriate “pig-tail” cable lug ends
under the skid rail (for strain-relief) through the
desired front and/or rear corner channels to the
exposed 0.5" (13 mm) stud. Remove the flange
nut with a .75" (19 mm) wrench.
NOTE: Input supply cable(s) must connect through
“INPUT +” labeled channels, and output weld cable(s)
must connect through “ELECTRODE +” labeled
channels.
3. Slip the “pig-tail” cable lug(s) over the stud and re-
secure the flange nut. Make sure that the lug(s) do
not touch any sheetmetal of the stud housing. Fold
back the cover insulation and replace the stud
cover.
A-3 A-3
INSTALLATION
MULTI-WELD 350
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WARNING
BOTTOM VIEW
TO ELECT.
TO ELECT.
TO
WORK
TO POWER
SOURCE
TO POWER
SOURCE
+
INPUT +
ELECTRODE
ELECT.
+
ELECT.
+
+
IN
+
IN
FIGURE A.1 – PIG-TAIL CONNECTIONS

Be sure to follow the safety practice to
use the female connector on the cable
which would normally be electrically "hot"
(supply lead) if disconnected when the
system is energized, and the male on the
normally “cold” (load lead) side. If practical, shut off
power before connecting or disconnecting terminals.
WORK CONNECTION
Each Converter in the Multi-Weld system must have its
individual “Work” lead connected (clipped) to the work.
The #3 AWG (27 mm2) Work clip lead must have clean
metal connection to the work to complete the DC input
supply and output power circuits of the Multi-Weld 350.
Do not disconnect the Work clip lead without first
switching OFF the Converter panel switch. Failure to
do so will allow the Work lead clip to be electrically “hot”
to work and “hot” to the electrode, through the circuit of
the Converter, for about 5 seconds until the input con-
tactor opens.
CASE GROUNDING
As shipped, the case of the Multi-Weld 350 is isolated
from all of the DC input and output welding terminals.
It is equipped with a grounding terminal screw
(.31” / 7.9 mm) marked with the symbol located on
the bottom rear of the base assembly. (Refer to the bot-
tom view figure.) In order to comply with CSA and UL
case grounding specifications, this terminal is provided
for connection to weldment work that must be properly
grounded per methods meeting local and national elec-
trical codes. Refer to “Safety in Welding, Cutting and
Allied Processes,” ANSI Z49.1 (US) and W117.2
(Canada).
Since any case fault would only involve the DC welding
circuit, the size of the grounding lead should have the
capacity to ground the potential fault current without
burning open. Use at least #6AWG (13 mm2), but need
not exceed the size of the input cable supplying the
Multi-Weld 350.
Connect the Multi-Weld grounding lead to the work
piece separately from the Work clip. If the same clip is
used for both ground and work connection, the Multi-
Weld case will be electrically “hot” to the work if the clip
is removed without first switching OFF the panel
switch. ( Refer to the Work clip WARNING).
INTER-CONNECTION OF
CONVERTERS
The input and electrode cables of the Multi-Weld 350
Converters may be inter-connected in a Multi-Weld
system using any combination of Distribution Box(es)
(see Figure B.1), paralleling (CC mode only) and
“daisy-chaining” (see Figure A.2). Choose the config-
uration that best fits the field application setup within
the capacity of the power source supplying the system.
Power Source (Volts x Amp) capacity > 1.1 x
Sum of Converters’ (Volts x Amps) arcs
Paralelled units may be powered from more than one
source. Disconnect all inputs, including outputs from
other sources, before working on the equipment.
Before removing the parallel jumper, be sure both
Converters are switched OFF. If not, the male side of
the first disconnection will be electrically “hot” to work.
A-4 A-4
INSTALLATION
MULTI-WELD 350
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WARNING
WARNING
WARNING

A-5 A-5
INSTALLATION
MULTI-WELD 350
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DAISY CHAIN OPERATION
FIXED PARALLEL OPERATION
TO
WORK
TO POWER
SOURCE
TO WORK
TO ELECT.
TO POWER
SOURCE
TO WORK
TO ELECT.
TO WORK
TO ELECT.
SEPARABLE PARALLEL OPERATION
TO WORK
TO WORK
TO POWER
SOURCE
TO POWER
SOURCE
TO WORK
TO ELECT.
TO ELECT.
PARALLEL
JUMPER
+
IN +
IN
ELECT.
+
+
IN +
IN
ELECT.
+
+
IN +
IN
ELECT.
+
+
IN
ELECT.
+
+
IN
+
IN
ELECT.
+
ELECT.
+
ELECT.
+
ELECT.
+
FIGURE A.2 – INTER-CONNECTING CONVERTERS

For Converters (operating at rated output) less than
200 ft. (61 m) from the power source, the following min-
imum cable sizes are recommended for the indicated
quantity of Converters supplied by the input cable run
to keep cable temperature and voltage drop within
acceptable limits:
Converters Cable Size
on Cable AWG (mm2 )
1 1/0 (50)
2 2/0 (70)
3 3/0 (95)
4 4/0 (120)
5 2x3/0 (2x95)
The output “Electrode” cable should be 2/0 AWG
(70 mm2) if sized for rated output up to 200 ft.(61 m)
from the Converter. If paralleled, the output cable to the
arc should be 4/0 (120 mm2).
Do not disconnect the Work clip lead without first
switching OFF the Converter panel switch. Failure to
do so will allow the Work lead clip to be electrically “hot”
to work and “hot” to the electrode, through the circuit of
the Converter, for about 5 seconds until the input con-
tactor opens.
POWER SOURCE SETUP
Refer to the Instruction Manual provided with the Multi-
Source power source, or other DC power source being
used, for input power supply connections, output con-
nections and controls setup.
In general:
1. Connect the positive (+) output connection terminal
to the input supplying the Multi-Weld system and
the negative (-) output connection terminal to the
work. (See Figure A.1.)
2. If not using a Multi-Source power source:
a. If an inductance control, or tap, is selectable,
use lowest inductance.
b. Use CC (Constant Current) mode for maximum
supply voltage.
c. Set panel output control to maximum for maxi-
mum current capacity.
d. Activate output with the “output terminals on”
switch, or jumper (2-4 on Lincoln Electric termi-
nal strips).
A-6 A-6
INSTALLATION
MULTI-WELD 350
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WARNING

Operation...............................................................................................................................Section B
Safety Instructions.......................................................................................................................B-2
Product Description.....................................................................................................................B-3
Recommended Equipment and Processes.................................................................................B-4
Multi-System Power Source.................................................................................................B-4
Distribution Box.....................................................................................................................B-4
“Pig-Tail” Leads and Connectors..........................................................................................B-4
Remote Output Control Options...........................................................................................B-5
CV Mode Wire Welding........................................................................................................B-5
CC Mode Stick Welding and Gouging..................................................................................B-5
Front Panel Controls...................................................................................................................B-6
Recessed Panel Controls............................................................................................................B-7
Paralleled Converters..................................................................................................................B-8
Remote Control of Paralleled Converters...................................................................................B-8
Transporting and Storage of the Multi-Weld 350........................................................................B-8
Cable Handling.....................................................................................................................B-8
Transporting..........................................................................................................................B-9
Storage.................................................................................................................................B-9
Protection Features.....................................................................................................................B-9
Fan as Needed (F.A.N.)........................................................................................................B-9
Over-Voltage Protection........................................................................................................B-9
Over-Current Protection........................................................................................................B-9
Over-Temperature Shutdown................................................................................................B-9
Section B-1 Section B-1
TABLE OF CONTENTS
- OPERATION SECTION -
MULTI-WELD 350
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OPERATING INSTRUCTIONS
Read and understand this entire section of operating
instructions before operating the machine.
SAFETY INSTRUCTIONS
ELECTRIC SHOCK can kill.
• Do not touch electrically live parts or
electrodes with your skin or wet clothing.
• Insulate yourself from the work and
ground.
• Always wear dry insulating gloves.
FUMES AND GASES CAN BE
DANGEROUS.
• Keep your head out of fumes.
• Use ventilation or exhaust to remove
fumes from breathing zone.
WELDING SPARKS CAN CAUSE
FIRE OR EXPLOSION.
• Keep flammable material away.
• Do not weld on containers that have held
combustibles.
ARC RAYS CAN BURN.
• Wear eye, ear, and body protection.
Observe additional Safety Guidelines detailed in
the beginning of this manual.
B-2 B-2
OPERATION
MULTI-WELD 350
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WARNING

PRODUCT DESCRIPTION
The Multi-Weld 350 Arc Converter (K1735-1) is part of
a Multi-Weld system, ideally suited for construction site
welding. It uses a single DC power source as the
only input supply and provides independent, full-range
control of up to 350A continuous with each Converter
arc for + polarity stick and wire processes, as well as
for arc-air gouging. (See Figure B.1.)
The Multi-Weld 350 is a DC to DC Converter that con-
verts higher voltage/lower current input power to lower
voltage/higher current output power with over 90% effi-
ciency.
For example, a single 600A continuous rated 70-80V
power source could supply up to five Multi-Weld 350
converters, each wire welding at 300 amps, or about
ten converters for stick welding at 150 amps with 26-
29V at the arcs.
The Multi-Weld 350 Arc Converter is a single “world”
model built to IEC and CSA standards and meeting the
specific needs inherent to construction site welding:
Versatile
• Constant Current (CC) mode for stick and gouging.
Includes Hot Start and Arc Force controls to optimize
CC performance, and can be paralleled for higher
capacity welding and arc gouging.
• Constant Voltage (CV) mode for positive polarity
cored and solid wire welding with arc-powered feed-
ers (such as the LN-25).
Portable
• The Multi-Weld 350 can be moved quickly. The light-
weight Converter is easy to carry or pull and is small
enough to fit through a 15" (38 cm) diameter or 12" x
16" (31x 41 cm) elliptical man-hole.
• The Converter is powered by the welding cable from
the DC power source, without the safety hazard of
high AC input supply voltages.
• Welding controls are near the arc without long con-
trol cables, and a receptacle is provided for an
optional remote for even closer user output control.
B-3 B-3
OPERATION
MULTI-WELD 350
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FIGURE B.1 – MULTI-WELD SYSTEM

Simple
• Easy installation with 10 ft. (3 m) work clip lead and
user preference quick-connect “pig-tails” for input
and electrode weld cables.
• Easy setup with only a few intuitive welding controls
and lit displays. This includes a single Power/Mode
switch with Input level light, and a single presettable
Output Control with separate digital meters for Amps
and Volts, featuring post-weld five second memory
display.
• Easy Service with quick-to-replace cable “pig-tails”
and “plug-in” assembly modules, including accessi-
ble PC boards and interchangeable “plug-n-play”
panel instruments.
Robust
• Capacity is rated for continuous operation at 350
amps in 50°C (122°F) ambient temperature, and can
be paralleled to multiply CC mode output rating.
• Overload protection is provided with electronic limit-
ing of output current, and with thermostat and over-
voltage shutdown protection that automatically reset.
• Outdoor operation protected with sealed control and
power electronics compartments, with sealed inter-
connections, housing “potted” circuit boards, and
using “Central-Air” cooling with “Fan-As-Needed” for
less dirt intake.
• Handling (and mishandling protection) is enhanced
with light, but durably designed, aluminum construc-
tion with front to back, top and bottom, handles (also
serving as “roll bar” and skid), and a sheetmetal shell
attached with 1/4" steel threaded fasteners.
RECOMMENDED EQUIPMENT AND
PROCESSES
MULTI-SYSTEM POWER SOURCE
The Multi-Source 40KW, 80VDC buss power source
(K1752-1) is recommended for use in the Multi-Weld
system. However, other DC power sources capable of
supplying the required system buss current, at above
60 volts, may be used. It is recommended that this
power source have lower output inductance (choke)
such as the Lincoln Electric DC-1000, DC-655 or DC-
600 set for maximum output in CC mode. The power
source output VA capacity should be 10% greater than
the sum of the maximum VA of the converter arcs,
which may all be simultaneously welding or gouging:
Power Source (Volts x Amps) capacity > 1.1 x
Sum of Converters’ (Volts x Amps) arcs
DISTRIBUTION BOX
The Multi-Weld Distribution Box (K1736-1) is available
for interconnection of the Multi-System using the same
“pig-tail” connection method provided with the Multi-
Weld 350 converter. Six cable strain-relief ports are
provided for connection of up to (12) cables for distrib-
ution or "daisy-chain" inter-connection to other boxes.
Four “pig-tail” leads (see below) are included with the
Box.
“PIG-TAIL” LEADS AND CONNECTORS
Accessory “pig-tail” leads and Twist-Mate connectors
are available from Lincoln for extra connections to the
Multi-Weld 350 or the Distribution Box:
Order No. Description:
CL012705 22 in.(56 cm) long 2/0 (70 mm2) cable
with 0.5 in.(13 mm) hole lug and cut-off
ends.
K852-70 Twist-Mate male insulated plug for
1/0-2/0 (50-70 mm2) cable.
K852-95 Twist-Mate male insulated plug for
2/0-3/0 (70-95 mm2) cable.
K1759-70 Twist-Mate female insulated receptacle
for 1/0-2/0 (50-70 mm2) cable.
K1759-95 Twist-Mate female insulated receptacle
for 2/0-3/0 (70-95 mm2) cable.
B-4 B-4
OPERATION
MULTI-WELD 350
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REMOTE OUTPUT CONTROL OPTIONS
The Multi-Weld 350 is provided with a 6-pin remote
receptacle to permit use with the 25 ft.(7.6 m) K857 or
100 ft. (30.4 m) K857-1 Remote Output Control
options. The remote receptacle can also be used with
the LN-25 equipped with the K444-1 Remote Control
option. These remotes have single-turn resolution on a
Minimum to Maximum numbered dialplate.
CV MODE WIRE WELDING
The Converter in CV mode was designed for use with
an arc-powered wire feeder like the LN-25. The
Converter output is always “hot” when the mode switch
is not OFF. Therefore it is recommended that the LN-
25 model be equipped with the internal contactor in
order to have a “cold” electrode when the gun trigger is
released.
The CV mode recommended processes are positive
(+) polarity wire welding within the output capacity of
the Converter, including:
Flux Cored Arc Welding (FCAW)
Innershield: NS3M (5/64-3/32)
NR305 (.068)
Outershield: OS-70 (1/16-5/64)
OS-71 (.045-1/16)
MC-710 (.045-5/64)
Gas Metal Arc Welding (GMAW)
Carbon Steel: L50/56 (.030-1/16)
CC MODE STICK WELDING
AND GOUGING
The CC mode recommended processes are positive
(+) polarity stick and arc gouging within the output
capacity of single, or paralleled, Converters, including:
Shielded Metal Arc Welding (SMAW)
E6010/6011: FW5P/180 (3/32-1/4)
“fast-freeze”
E6013: FW37 (3/32-3/16)
“fill-freeze”
E7010/8010: SA85/70+ (3/32-7/32)
“fast-freeze” HT pipe
E7018/7028: JW LH70/3800 (3/32-5/32)
“low-hydrogen”
E7024/6027: JW1,3/2 (1/8-5/16)
“fast-fill”
Arc Air Carbon (AAC)
Gouging: Carbons (5/32-3/8)
B-5 B-5
OPERATION
MULTI-WELD 350
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FRONT PANEL CONTROLS
The numbered items of Figure B.2 match the num-
bered items described below:
These few instruments and controls are basic to the
operation and monitoring of the Converter. They are
intuitively laid out so that the panel left side is weld cur-
rent related, and the right side is weld voltage related:
(1) Input Power/ Mode Switch has three positions:
Center is OFF, which shuts off input power to the
Converter.
• Neither displays nor output is on if in OFF
position.
Left is on for CC (constant current) welding mode.
• Only AMPS digital meter is lit, displaying the
preset current setting.
• Output will be on at o.c.v. (open circuit voltage).
Right is on for CV (constant voltage) welding
mode.
• Only VOLTS digital meter is lit, displaying the
preset voltage setting.
• Output will be on at the output voltage setting.
(2) Output Control has 3-3/4 turn resolution with slip-
clutch to prevent control pot damage.
In CC mode it presets AMPS (30-350A range)
when not welding and adjusts actual arc current
while welding.
In CV mode it presets VOLTS (15-40v range)
when not welding and adjusts actual arc voltage
while welding.
(3) AMPS Digital Meter is a 3-1/2 digit LED meter
which displays:
Preset AMPS in CC mode when not welding.
“Blank” in CV mode when not welding.
Actual AMPS while welding in both CC and CV
modes.
B-6 B-6
OPERATION
MULTI-WELD 350
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1
2
34
5
7
8
9
10
INPUT
WORK
ELECTRODE
++
FIGURE B.2 – FRONT PANEL CONTROLS

Average AMPS for about 7 seconds after welding
stops in CC and CV modes only.
• The 5 second memory display is indicated by the
display’s left-most decimal point blinking, and is
interrupted if arc is restarted.
Accuracy ofActual AMPS is within 3%, and typical-
ly within 10 amps of Preset.
• An Actual AMPS meter calibration adjustment
trimmer is provided. (See the Maintenance sec-
tion).
Two front screws secure the meter bezel, which
holds a replaceable spatter shield lens (Lincoln
part no. T14807-9).
(4) VOLTS Digital Meter is a 3-1/2 digit LED meter
which displays:
Preset VOLTS in CV mode when not welding.
“Blank” in CC mode when not welding.
Actual VOLTS while welding in both CV and CC
modes.
Average VOLTS for about 7 seconds after welding
stops in CV and CC modes only.
• The 7 second memory display is indicated by the
display’s left-most decimal point blinking, and is
interrupted if arc is restarted.
Accuracy of Actual VOLTS is within 3%, and typi-
cally within 1 volt of Preset.
• An Actual VOLTS meter calibration adjustment
trimmer is provided. (See the Maintenance sec-
tion).
Two front screws secure the meter bezel, which
holds a replaceable spatter shield lens.
(5) Thermal Shutdown (yellow) Light turns on if out-
put is shutdown because internal overheating has
occurred. (See Over Temperature Shutdown in
this section).
(6) Input Voltage (green) Light indicates appropriate
level of input supply voltage:
“On” for adequate input voltage over 50 V for CC or
CV mode.
“Off” for inadequate input voltage under 50 V, no
input or Power Switch OFF.
NOTE: If green light is “blinking,” the input voltage may
be drifting above and below the 50 V level due to loads
on supply and cables. This may also cause the input
contactor to “chatter.”
RECESSED PANEL CONTROLS
These instruments are recessed behind a screw-
secured hinged cover panel, and are not typically
required for normal operator access. They may be left
covered, as factory set, or set up as desired with or
without the hinged cover secured:
(7) Hot Start Control is provided to enhance arc
starting in both CC and CV modes with an extra
output “boost” at the arc strike that returns to the
setting level in less than a second (about 0.30
sec. in CC mode, and 0.045 sec. in CV mode).
This extra Hot Start amplitude is adjustable from
“0” (no extra) to “10” (100% of setting extra), with
the factory set “5” (center) position typically good
for most weld starting. However, “0” may provide
smoother starting for fine wire CV MIG.
(8) Arc Force Control is only functional in the CC
mode with Stick/Gouge slope. (See below). Arc
Force prevents “stubbing” of the electrode by pro-
viding extra weld current if the arc voltage drops
below about 14 V. This extra weld current is
adjustable from “-10” (no extra) to “+10” (60% of
setting extra), with the factory set “0” (center)
position typically good for most welding.
(9) CC Slope Switch is provided to enhance stick
welding on “fast-freeze” type electrodes (such as
E6010 and E7010) typically used on pipe welding
applications for fast root pass vertical down
"drag" technique (not “whipping”). For this type of
application, improved operating appeal may be
obtained if the CC Slope is switched from the fac-
tory set STICK/GOUGE position to the PIPE
position.
NOTE: The PIPE position uses a “drooping” type
slope (~22v/100A), so preset current (not actual
current) accuracy may be affected if arc length
voltage is not maintained at the typical 28 V used
for these electrodes. Typically this error should
not be more than about 10 A.
(10) Remote Control Receptacle is provided to per-
mit the use of an optional Remote output control
to provide operator control even closer to the arc.
Connecting the Remote plug to this receptacle
automatically transfers output control from the
panel Output Control (item (2) above) to the
Remote pot control, which will function the same
but with only single-turn resolution.
B-7 B-7
OPERATION
MULTI-WELD 350
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Disconnecting the Remote plug from this recepta-
cle automatically transfers output control back to
the panel Output Control (item (2) above).
Remote output On/Off switching can also be done
through this Remote Control receptacle by per-
forming the following wiring changes:
1. Making sure the input to the Converter is
removed, remove the case wraparound.
2. Locate the 4-pin plug (P21) on the back panel
of the control box module, and cut the jumper
lead looping from the back of the plug. (Refer to
the Wiring Diagram in the Electrical Diagrams
section.) Insulate the cut lead ends and leave
long enough to possibly splice back together
again at some future time.
3. Replace the case wraparound.
4. Connect a user-provided remote switch be-
tween pins D and E of an MS3106A-18-12P
plug (Lincoln part no. S12020-27 with S12024-
1 cable clamp). See the diagram below:
Pin: Remote Function:
A Max. of 10K pot
B Wiper of 10K pot
C Min. of 10K pot
D Output Switch
E Output Switch
F No connection
5. Connect this switch plug to the Multi-Weld 350
Remote Control Receptacle (10) with switch
opened. Closing the switch activates the
Converter output.
PARALLELED CONVERTERS
Multi-Weld 350 converters that are paralleled (see INTER-
CONNECTION OF CONVERTERS in the Installation
section) must each be set up in the same manner in order
to manage the arc current drawn from each:
1. Set to CC mode with CC SLOPE switch set to
STICK/GOUGE.
2. Preset Output Controls of both paralleled
Converters to ~1/2 desired total AMPS.
If arc current from each Converter gets too out of bal-
ance (primarily a problem if trying to use CV mode) the
hotter running Converter could go into current-limiting
and/or Thermal shutdown (See OVER-TEMPERA-
TURE SHUTDOWN in the Installation section.) This
might then overload the other, or at least interrupt the
operator’s process. However, no damage will occur to
the Converters.
REMOTE CONTROL OF
PARALLELED CONVERTERS
(FOR CC STICK/GOUGE MODE ONLY)
Full Range remote control can be accomplished with a
separate optional Remote output control (see the
Installation section) connected to each Converter. The
current contribution of each Converter will depend on
its remote output setting.
Partial Range remote control can be accomplished with
a single Remote Control connected to the output
Converter. The input Converter must be preset with its
panel Output Control to below the minimum desired
output range. The Remote Control, connected to the
output Converter, will control its output to add to the
preset level.
Remote Output On/Off switching may be set up for
each of the paralleled Converters. Electrically isolated
switches must be used to activate each separately but
simultaneously.
TRANSPORTING AND STORAGE
OF THE MULTI-WELD 350
CABLE HANDLING
The input and electrode cables are easily disconnect-
ed from the quick-connect “pig-tails.” The Work lead
can be reeled around the Multi-Weld 350 case cradled
by the base skid handles, to which the clip can be
secured.
B-8 B-8
OPERATION
MULTI-WELD 350
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AFE
BD
C