Lincoln Electric IM664 User Manual

®

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Multi-Weld 350 Arc Converter

IM664-C

September, 2011

For use with machines having Code Numbers:

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.

10645
10736
11148
11854

LINCOLN

ELECTRIC

®

MULTI-WELD 350

350

LINCOLN

ELECTRIC

340

®

MULTI-WELD 350

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

OPERATORʼS MANUAL

Copyright © Lincoln Global Inc.

• World's Leader in Welding and Cutting Products •

• Sales and Service through Subsidiaries and Distributors Worldwide •

i

SAFETY

i

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

____________________________________________________

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

____________________________________________________

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

____________________________________________________

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

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

___________________________________________________

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

1.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.

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.

ii

SAFETY

ii

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 within applicable OSHA PEL and
ACGIH TLV limits 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

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.

5.f. Also see item 1.b.

iii

SAFETY

iii

WELDING and CUTTING
SPARKS can
cause fire or explosion.

6.a.

Remove fire hazards from the welding area.

If this is not possible, cover them to prevent

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.

the welding sparks from starting a fire.

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.

Refer to http://www.lincolnelectric.com/safety for additional safety information.

iv

SAFETY

iv

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 lʼélectrode et à la piéce sont sous tension

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

b. Faire trés attention de bien sʼisoler de la masse quand on

soude dans des endroits humides, ou sur un plancher
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 lʼeau pour le

refroidir.

e. Ne jamais toucher simultanément les parties sous tension

des porte-électrodes connectés à deux machines à souder
parce que la tension entre les deux pinces peut être le
total de la tension à vide des deux machines.

f. Si on utilise la machine à souder comme une source de

courant pour soudage semi-automatique, ces precautions
pour le porte-électrode sʼapplicuent aussi au pistolet de
soudage.

zones où lʼon pique le laitier.

6. Eloigner les matériaux inflammables ou les recouvrir afin de
prévenir tout risque dʼincendie 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 dʼincendie.

8. Sʼassurer que la masse est connectée le plus prés possible
de la zone de travail quʼil est pratique de le faire. Si on place
la masse sur la charpente de la construction ou dʼautres
endroits éloignés de la zone de travail, on augmente le risque
de voir passer le courant de soudage par les chaines de lev­age, câbles de grue, ou autres circuits. Cela peut provoquer
des risques dʼincendie ou dʼechauffement des chaines et des
câbles jusquʼà ce quʼils se rompent.

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

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

11. Pour obtenir de plus amples renseignements sur la sûreté,
voir le code “Code for safety in welding and cutting” CSA
Standard W 117.2-1974.

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

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

a. Utiliser un bon masque avec un verre filtrant approprié

ainsi quʼun verre blanc afin de se protéger les yeux du ray­onnement de lʼarc et des projections quand on soude ou
quand on regarde lʼarc.

b. Porter des vêtements convenables afin de protéger la

peau de soudeur et des aides contre le rayonnement de
lʻarc.

c. Protéger lʼautre personnel travaillant à proximité au

soudage à lʼaide dʼécrans appropriés et non-inflammables.

4. Des gouttes de laitier en fusion sont émises de lʼarc de
soudage. Se protéger avec des vêtements de protection libres
de lʼhuile, tels que les gants en cuir, chemise épaisse, 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

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
lʼélectricité et aux recommendations du fabricant. Le dispositif
de montage ou la piece à souder doit être branché à une
bonne mise à la terre.

2. Autant que possible, Iʼinstallation et lʼentretien du poste seront
effectués par un électricien qualifié.

3. Avant de faires des travaux à lʼinterieur de poste, la debranch­er à lʼinterrupteur à la boite de fusibles.

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

Thank You

vv

for selecting a QUALITY product by Lincoln Electric. We want you
to take pride in operating this Lincoln Electric Company product

••• as much pride as we have in bringing this product to you!

The business of The Lincoln Electric Company is manufacturing and selling high quality welding equipment, consumables, and cutting equip­ment. Our challenge is to meet the needs of our customers and to exceed their expectations. On occasion, purchasers may ask Lincoln
Electric for advice or information about their use of our products. We respond to our customers based on the best information in our posses­sion at that time. Lincoln Electric is not in a position to warrant or guarantee such advice, and assumes no liability, with respect to such infor­mation or advice. We expressly disclaim any warranty of any kind, including any warranty of fitness for any customer’s particular purpose,
with respect to such information or advice. As a matter of practical consideration, we also cannot assume any responsibility for updating or
correcting any such information or advice once it has been given, nor does the provision of information or advice create, expand or alter any
warranty with respect to the sale of our products.

Lincoln Electric is a responsive manufacturer, but the selection and use of specific products sold by Lincoln Electric is solely within the control
of, and remains the sole responsibility of the customer. Many variables beyond the control of Lincoln Electric affect the results obtained in
applying these types of fabrication methods and service requirements.

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

CUSTOMER ASSISTANCE POLICY

Please Examine Carton and Equipment For Damage Immediately

When this equipment is shipped, title passes to the purchaser upon receipt by the carrier. Consequently, Claims
for material damaged in shipment must be made by the purchaser against the transportation company at the
time the shipment is received.

Please record your equipment identification information below for future reference. This information can be
found on your machine nameplate.

Product _________________________________________________________________________________

Model Number ___________________________________________________________________________

Code Number or Date Code_________________________________________________________________

Serial Number____________________________________________________________________________

Date Purchased___________________________________________________________________________

Where Purchased_________________________________________________________________________

Whenever you request replacement parts or information on this equipment, always supply the information you
have recorded above. The code number is especially important when identifying the correct replacement parts.

On-Line Product Registration

- Register your machine with Lincoln Electric either via fax or over the Internet.

• For faxing: Complete the form on the back of the warranty statement included in the literature packet
accompanying this machine and fax the form per the instructions printed on it.

• For On-Line Registration: Go to our

Your Product”. Please complete the form and submit your registration.

Read this Operators Manual completely before attempting to use this equipment. Save this manual and keep it
handy for quick reference. Pay particular attention to the safety instructions we have provided for your protection.
The level of seriousness to be applied to each is explained below:

WEB SITE at www.lincolnelectric.com. Choose “Support” and then “Register

WARNING

This statement appears where the information must be followed exactly to avoid serious personal injury or loss of life.

CAUTION

This statement appears where the information must be followed to avoid minor personal injury or damage to this equipment.

vi

TABLE OF CONTENTS

Page

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

Technical Specifications.......................................................................................................A-1

Product Description. .............................................................................................................A-2

Recommended Equipment and Processes ..........................................................................A-3

Multi-System Power Source..........................................................................................A-3

Distribution Box .............................................................................................................A-3

“Pig-Tail” Leads and Connectors ..................................................................................A-3

Remote Output Control Options....................................................................................A-4

CV Mode Wire WElding ................................................................................................A-4

CC Mode Stick Welding and Gouging...........................................................................A-4

Quick-Connect “Pig-Tails” ....................................................................................................A-4

Attachment and Arrangement of “Pig-Tails” .........................................................................A-4

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

Case Grounding ...................................................................................................................A-5

Inter-Connection of Converters ............................................................................................A-6

Connection for Negative Polarity Welding............................................................................A-7

Power Source Setup ............................................................................................................A-7

________________________________________________________________________________

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

Front Panel Controls ............................................................................................................B-1

Recessed Panel Controls.....................................................................................................B-2

Paralleled Converters...........................................................................................................B-3

Remote Control of Paralleled Converters.............................................................................B-3

Transporting and Storage of the Multi-Weld 350..................................................................B-4

Cable Handling..............................................................................................................B-4

Transporting ..................................................................................................................B-4

Storage..........................................................................................................................B-4

Protection Features .............................................................................................................B-4

Fan as Needed (F.A.N.) ................................................................................................B-4

Over-Voltage Protection................................................................................................B-4

Over-Current Protection ................................................................................................B-4

Over-Temperature Shutdown........................................................................................B-5

________________________________________________________________________________

vi

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

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

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

Digital Meter Calibration ......................................................................................................

D-1

Service .................................................................................................................................D-2

________________________________________________________________________________

Troubleshooting .............................................................................................................Section E

How to use Troubleshooting Guide ......................................................................................E-1

Troubleshooting Guide ...........................................................................................E-2 thru E-5

________________________________________________________________________________

Wiring Diagram and Dimension Prints..........................................................Section F

________________________________________________________________________

Parts Lists...................................................................................................P-361 Series

________________________________________________________________________

A-1

INSTALLATION

TECHNICAL SPECIFICATIONS - Multi-Weld 350 (K1735-1)

ELECTRICAL SPECIFICATIONS

AMPS

(DC+)

A-1

VOLTS

(DC+)

Output Rating @ 50ºC (122°F)

Input Rating @ 50ºC (122°F)

Max. Input Range

Max. O.C.V.

Output Preset Range

HEIGHT

11.6 in

295 mm

WIDTH

10.0 in

254 mm

TEMPERATURE RANGES

OPERATING TEMPERATURE RANGE

-40 to +122°F

-20 to + 50°C

350

165

30-350

34

80

50-113 (Peak)

78

15-40

PHYSICAL DIMENSIONS

DEPTH

21.5 in

546 mm

STORAGE TEMPERATURE RANGE

-40 to +185°F

-40 to +85°C

NET WEIGHT

59.5 lbs.

27.0 kg.

MULTI-WELD 350

A-2

INSTALLATION

A-2

PRODUCT DESCRIPTION

The Multi-Weld 350 converter (K1735-1) is part of a
Multi-Weld system, ideally suited for construction site
welding, which uses a single DC power source, as the

MULTI-WELD SYSTEM

®

CONVERTER

MULTI-SOURCE

MULTI-SOURCE

LINCOLN

ELECT

®

RIC

LINCOLN

ELECTRIC

®

MULTI-SOURCE

LINCOLN

ELECTRIC

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 1).

LI
NC
OL

ELEC

N

TRIC

®

MULTI-WELD 350

350

®

MULTI-WELD 350

COLN

LIN

TRIC

ELEC

DISTRIBUTION
BOX

340

CONVERTER

LINC
OL

EL
EC

N

TR

®

IC

MULTI-WELD 35

0

®

LINCOLN

LN-25

ELECTRIC

WIRE FEEDER

340

350

®

MULTI-WELD 350

LN

LINCO

ELECTRIC

WIRE

STICK

Figure 1

The Multi-Weld 350 is a DC to DC converter which
converts higher voltage/lower current input power to
lower voltage/higher current output power with over
90% efficiency.

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 26­29v at the arcs.

The 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 opti-

PARALLEL

CONVERTERS

mize CC performance, and can be paralleled for
higher capacity welding and arc gouging.

• Constant Voltage (CV) mode for positive polarity

Portable

• Arcs can be moved quickly with the light weight

• Converter is powered by the welding cable from

LINC
OLN

ELECTR

®

IC

MULTI-WELD 350

LINCOLN

ELE

CTRIC

®

MULTI-WELD 350

350

®

MULTI-WELD 350

LINCOLN

TRIC

ELEC

340

350

®

MULTI-WELD 350

LN

LINCO

TRIC

ELEC

340

700 AMP ARC GOUGE

cored and solid wire welding with arc-powered
feeders (such as the LN-25).

Converter thatʼs easy to carry, or pull, and is small
enough to fit through a 15" (38cm) diameter or 12"
x 16" (31x 41cm) elliptical man-hole.

the DC power source, without the safety hazard of
high AC input supply voltages.

MULTI-WELD 350

A-3

INSTALLATION

A-3

• Converter welding controls are near the arc without
long control cables, and a receptacle is provided
for an optional remote for even closer user output
control.

Simple

• Easy installation with 10 ft. (3m) work clip lead and
user preference quick-connect "pigtails" for input
and electrode weld cables.

• Easy setup with only a few intuitive welding
controls and lit displays; including a single
Power/Mode switch with Input level light, and a
single presettable Output Control with separate
digital meters for Amps and Volts, featuring post­weld five second memory display.

• Easy Service with quick to replace cable "pig­tails"and "plug-in" assembly modules, including
accessible PC boards and interchangeable "plug­n-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 lim­iting of output current, and with thermostat and
over-voltage shutdown protection which automati­cally reset.

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 DC­600 set for max. output in CC mode. The power
source output VA capacity should be 10% greater
than the sum of the max. VA of the converter arcs
which may all be simultaneously welding or gouging:

Power Source (Volts x Amps) capacity > 1.1 x Sum

of Convertersʼ (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
distribution or "daisy-chain" inter-connection to other
boxes. Four "pig-tail" leads (see below) are included
with the Box.

"PIG-TAIL" LEADS AND CONNECTORS

• Outdoor operation protected with sealed control
and power electronics compartments, with sealed
interconnections, housing "potted" circuit boards,
and using "Central-Air" cooling with "Fan-As­Needed" for less dirt intake.

• Handling (and mishandling protection) is enhanced
with light, but durably designed, aluminum con­struction 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.

MULTI-WELD 350

Accessory "pig-tail" leads and Twist-Mate connectors
are available from Lincoln for extra connections to the
Muli-Weld 350 or the Distribution Box:

Order No. Description:

CL012705 22in.(56cm) long 2/0 (70mm2) cable

with 0.5in.(13mm) hole lug and cut-off
ends.

K852-70 Twist-Mate male insulated plug for

1/0-2/0 (50-70mm2) cable.

K852-95 Twist-Mate male insulated plug for

2/0-3/0 (70-95mm2) cable.

K1759-70 Twist-Mate female insulated recepta-

cle for 1/0-2/0 (50-70mm2) cable.

K1759-95 Twist-Mate female insulated recepta-

cle for 2/0-3/0 (70-95mm2) cable.

A-4

INSTALLATION

A-4

REMOTE OUTPUT CONTROL OPTIONS

The Multi-Weld 350 is provided with a 6-pin remote
receptacle to permit use with the 25ft.(7.6 m) K857 or
100ft.(30.4 m) K857-1 Remote Output Control options,
or with the LN-25 equipped with the K444-1 Remote
Control option. These Remotes have single-turn reso­lution on a Min to Max 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, so it is recommended that the LN­25 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:

CC MODE STICK WELDING
AND GOUGING

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 cable channels, and/or into the back for single or
double "pig-tail" cables to the bottom-accessed cov­ered cable connection studs. (See below and refer to
Figures 1 and 2.):

TO

WORK

INPUT

+

BOTTOM VIEW

TO ELECT.

ELECTRODE

+

ELECT.

+

IN

+

TO POWER

SOURCE

The CC mode recommended processes are positive
(+) polarity stick and arc gouging within the output
capacity of single, or paralleled, Converters; including:

QUICK-CONNECT "PIG-TAILS"

The Multi-Weld 350 is factory provided with two 21
in.(53 cm) long 2/0 AWG (70mm2 ) "pig-tail" cables
with their 0.5"(13mm) hole lug ends routed through
the "INPUT + "(on back) and "ELECTRODE + "(on
front) cable channels of the Converter and attached to
the bottom-accessed covered cable connection studs.

Attach the preferred standard user-provided Quick­connect 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.

IN

+

TO POWER

SOURCE

TO ELECT.

ELECT.

+

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"(6.3mm)
screws securing 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"(13mm) stud, and remove the flange
nut with a .75"(19mm) 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, making sure that lug(s)
nowhere touch any sheet metal of the stud hous­ing, then fold back the cover insulation and
replace the stud cover.

MULTI-WELD 350

A-5

INSTALLATION

WARNING

ELECTRIC SHOCK can kill.

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 work. The
#3 AWG (27mm2) 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.

WARNING

ELECTRIC SHOCK can kill.

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 contactor
opens.

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

CASE GROUNDING

As shipped, the case of the Multi-Weld 350 is isolated
from all of the DC input and output welding terminals,
and is equipped with a grounding terminal screw (.31”
/ 7.9mm) marked with the symbol located on the
bottom rear of the Base assembly. ( Refer to the bot­tom view figure.) In order to comply with CSA and UL
case grounding specifications, this terminal is provid­ed for connection to weldment work which must be
properly grounded per methods meeting local and
national electrical 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 (13mm
do not exceed the size of the input cable suppled with
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 Multi­Weld 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 above).

2

), but

A-5

MULTI-WELD 350

A-6

T

INSTALLATION

A-6

INTER-CONNECTION OF CONVERTERS

Power Source (Volts x Amp) capacity > 1.1 x Sum of

Convertersʼ (Volts x Amps) arcs

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 1), paralleling ( CC mode only) and
"daisy-chaining" (see Figure 2) which best fits the
field application setup within the capacity of the power
source supplying the system:

For Converters (operating at rated output) less than
200ft. (61m) from the power source, the following mini­mum 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: (See Table.1)

FIXED PARALLEL OPERATION

ELECT.

+

TO ELECT.

TO WORK

IN

+

O POWER

SOURCE

ELECT.

+

TO

WORK

IN

+

IN

+

ELECT.

+

IN

+

DAISY CHAIN OPERATION

ELECT.

+

TO ELECT.

TO WORK

TO WORK

TO POWER

SOURCE

IN

+

IN

+

IN

+

ELECT.

+

TO ELECT.

TO WORK

SEPARABLE PARALLEL OPERATION

ELECT.

+

TO POWER

SOURCE

IN

+

WARNING

ELECTRIC SHOCK can kill.

Paralled 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.

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

TO WORK

TO POWER

SOURCE

Figure 2

TO ELECT.

PARALLEL

JUMPER

ELECT.

+

IN

+

ELECT.

+

TO ELECT.

TO WORK

MULTI-WELD 350

A-7

-

+

ork

W

or

k

LN-25 Wire

Feeder

ork

-3

5

(-) Work Leadad

to

(-) PPowowe

r Souourcrce ss

tud

a

nd

(-)

E

lectrode Lead

MW-35350 0 (+) ) Outpuput

Lea

d

t

o Work

MULT

I-WELD 350

Negative Polarity

DC

POWER

SOURCE

INSTALLATION

A-7

Table .1

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

2

(70mm

) if sized for rated output up to 200 ft.(61m)
from the Converter. If paralleled, the output cable to
the arc should be 4/0(120mm2).

WARNING

ELECTRIC SHOCK can kill.

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
contactor opens.

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

CONNECTION FOR NEGATIVE
POLARITY WELDING (See Figure 2A)

This connection method will only permit using one
Multi-Weld arc on one power source, and cables have
to be run to the Multi-Weld from both (+) and (-) output
studs of the power source. This is required so that the
(-) electrode has a return path to both the Multi-Weld
and the Power Source, just like the normal (+)polarity
connection has a (-) return path to both the Multi-Weld
(through the Work Clamp) and to the Power Source
(through work connections). Both cable sizes are the
same, with capacity as recommended for normal (+)
connection.

If the power source itself can not perform the CV
negative welding process, the Multi-Weld is basically
serving very well as a process converter (ei; CV from
a CC power source), as well as a remote output
control. The advantage is that the same equipment
(Multi-Welds and CC Power Sources) is used for all
weld process applications.

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 connections 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 1).

A Multi-Weld 350 may be used for Negative (straight)
polarity CV (Innershield) or CC processes if
connected per the diagram shown below:

CAUTION

No more than one Multi-Weld 350 may be
connected to a power source for Negative Polarity
welding. Multiple units connected to the same
power source may cause damage to the Multi­Weld 350.

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

DC
POWER
SOURCE

MWMW-3

(-)

(-)

MUL

0 0(-)

r

tu

nd

lectrode Lead

MULTI-WELD 350

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 LE Co terminal strips).

Figure 2A

I-WELD 350

Lea

or

LN-25 Wire
Feeder

Negative Polarity

o

WWor

WWor

B-1

OPERATION

B-1

3

5

8

7

1

WORK

4

6

2

9

10

+

INPUT

+

ELECTRODE

+

Figure 3

The numbered items of Figure 3, above, match the numbered items described below:

FRONT PANEL CONTROLS

These few instruments are basic to the operation and
monitoring of the Converter. They are intuitively laid
out so that the panelʼs left side is weld current 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).

• 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.

Right is on for CV (constant voltage) welding
mode.

MULTI-WELD 350

"Blank" in CV mode when not welding.

Actual Amps while welding in both CC and CV
modes.

B-2

OPERATION

B-2

Average Amps for about 7 seconds after welding
stops in CC and CV modes .

• The 7 second memory display is indicated by
the displayʼs left-most decimal point blinking,
and is interrupted if arc is restarted.

Accuracy of Actual Amps is within 3%, and typi­cally within 10 amps of Preset.

• An Actual Amps meter calibration adjustment
trimmer is provided. (See MAINTENANCE sec­tion).

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.

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 setup as desired with or
without the hinged cover secured:

Hot Start Control is provided to enhance arc start-

(7)

ing 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.

(8) Arc Force Control in the CC mode with

Stick/Gouge slope.(See below). Arc Force prevents
"stubbing" of the electrode by providing extra weld
current if the arc voltage drops below about 14V.
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.

Average Volts for about 7 seconds after welding
stops in CV and CC modes .

• The 7 second memory display is indicated by
the displayʼs left-most decimal point blinking,
and is interrupted if arc is restarted.

Accuracy of Actual Volts is within 3%, and typical­ly within 1 volt of Preset.

• An Actual Amps meter calibration adjustment

trimmer is provided. (See MAINTENANCE
section).

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 50v for CC
or CV mode.
"Off" for inadequate input voltage under 50V, no
input or Power Switch OFF.

Note: If green light is "blinking" the input voltage may
be drifting above and below the 50V level due to loads
on supply and cables.

In CV mode this control functions like an induct-
ance (or “pinch”) control to provide a “softer” less
penetrating arc when set toward “+10”, or a
“harsher” more penetrating arc when set toward

“-10”.

(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"). If using this type of
application improved operating appeal may be
obtained if the CC Slope is switched from the fac­tory 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 28V
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 Remoteʼs 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.

MULTI-WELD 350

B-3

OPERATION

PARALLELED CONVERTERS

B-3

Disconnecting the Remoteʼs plug from this recep­tacle automatically transfers output control back
to the panel Output Control (item (2) above).

Remote output On/Off switching can also be
done thru this Remote Control receptacle. by per­forming 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 this
manual.) 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

between pins D and E of an MS3106A-18­12P plug (Lincoln part no. S12020-27 with
S12024-1 cable clamp). See diagram
below:

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 bal­ance (primarily a problem if trying to use CV mode)
the hotter running Converter could go into current-lim­iting and/or Thermal shutdown (See OVER-TEMPER­ATURE SHUTDOWN in the INSTALLATION section),
which might then overload the other, or at least inter­rupt the operatorʼs 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
INSTALLATION section) connected to each
Converter. The current contribution of each Converter
will depend on its remote output setting.

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.

MULTI-WELD 350

Partial Range remote control can be accomplished
with a single Remote Control connected to the output
Converter with the input Converter 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 maybe setup for
each of the paralleled Converters, but isolated, or
double-pole, switches must be used to activate each
separately but simultaneously.

B-4

OPERATION

TRANSPORTING AND STORAGE
OF THE MULTI-WELD 350

CABLE HANDLING

The input and electrode cables are easily disconnect­ed from the quick-connect "pig-tails", and 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.

TRANSPORTING

The Converter may be carried by one or two persons
using the front and rear top and bottom handles. It can
also be set vertically on a two wheel cart, or horizon­tally on a wagon, to convey it longer distances.

STORAGE

The Multi-Weld 350 may be set on a floor, or shelf,
horizontally on its skid, or vertically standing on its
rear top and bottom handles.

PROTECTION FEATURES

The Multi-Weld 350 design features electronic protec­tion systems to help assure reliable operation even
under adverse conditions. These systems include:

FAN AS NEEDED (F.A.N.)

The cooling fan will turn on when the arc starts and
remain on for about a minute after the arc is out to
cool down the power components.

This feature electronically controls the fan so it does
not run continuously when the power switch is turned
on. This will minimize the amount of contaminate and
clogging debris which may be drawn into the
Converter, in addition to the "Central-Air" system
design which intakes lower velocity air through the
higher side louvers and blows out through the lower
back louvers with higher velocity.

B-4

Peak Input Voltage Protection

The Chopper PC Board will stop switching and inter­rupt the machine output whenever the input voltage
across the input capacitors exceeds their 150 volt rat­ing. The Thermal Shutdown (yellow) panel light will be
lit when this protection is activated (Refer to OVER­TEMPERATURE SHUTDOWN Section), and resets
when the voltage level drops below the protection
level. The input contactor also opens during this shut
down, until reset.

These features protects internal components of the
Converter from excessive voltage levels.

OVER-CURRENT PROTECTION

The max. output current of the Multi-Weld 350 is elec­tronically limited, to protect internal power compo­nents, so as not to exceed about 375 amps average
and 500 amps peak. When the current load starts to
exceed these limits the output is reduced (lower volt­age) to sustain these max. levels, until the current is
reduced. even to a shorted output.

Prolonged output at this max. current limit level may
eventually overheat the Converterʼs internal power
components causing over-temperature shutdown.
(See following section).

Short circuit protection is also provided to reduce max.
output current to about 200 amps if the output voltage
is reduced, by loading or current limiting (see above),
to below 14 volts for over 7 seconds (indicating a
shorted output). The output current must be interrupt­ed to reset this reduced protective level.

OVER-VOLTAGE PROTECTION

Average Input Voltage Protection

The Multi-Weld 350 input contactor will open if the
average input supply voltage is above 113VDC, and
will automatically reclose if the voltage drops back
below. During Over-Voltage Shutdown the panel dis­plays will be as appropriate for the non-welding mode.
(See FRONT PANEL CONTROLS in this section).

CAUTION

When the contactor recloses the output of the
Converter will reactivate. Switching OFF input
power prevents unexpected reactivation.

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

MULTI-WELD 350

B-5

OPERATION

OVER-TEMPERATURE SHUTDOWN

The Multi-Weld 350 has a temperature sensing ther­mostat on the input diode heatsink to protect the
power components within the Converter from over­heating. If this thermostat temperature exceeds
about95°C (203°F) the Converter will electronically
shut off the output,and turn on the Thermal Shutdown
(yellow) Light until the thermostat is cooled to reset.

A second over-load protection switch in the Imbalance
Protector Module is added to Multi-Weld 350 models
with codes 10736, and higher, but may be retrofitted
to original code 10645 models with the parts order
kit.This module senses for an imbalance of current
between the paralleled Chopper boards by sensing
the differential choke voltage. If this voltage exceeds
1V for a sustained time the Imbalance Protector will
also activate over-temperature shut down to protect
the higher current Chopper board from over heating.

Machines with code 11148, or higher, which use the
G4662-[ ] Peripheral PC Board, also include Peak
Input Voltage Protection that also lights the the
Thermal Shutdown (yellow) panel light if the unit out­put is shutdown (See OVER-VOLTAGE PROTEC­TION Section.).

B-5

CAUTION

When the thermostat resets the output of the
Converter will reactivate. Switching OFF input
power prevents reactivation, but also shuts off the
cooling fan which prolongs the reset time.

-----------------------------------------------------------------------­During Over-Temperature Shutdown the panel dis­plays will be as appropriate for the non-welding mode.
(See FRONT PANEL CONTROLS in this section),
except the fan will remain running and the Thermal
Shutdown (yellow) Light will be lit until reset. Typically,
If shutdown occurs repeatedly below 300 amps output
with fan running, imbalance of the Chopper board cur­rent may likely be the cause.

MULTI-WELD 350

D-1

MAINTENANCE

D-1

SAFETY PRECAUTIONS

WARNING

Have qualified personnel do the maintenance
work.

Always use the greatest care when working near

moving parts.

If a problem cannot be corrected by following the

instructions, take the machine to the nearest
Lincoln Field Service Shop.

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

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.

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

MAINTENANCE

The only maintenance which may be required for the
Multi-Weld 350 is to clean out any accumulated dirt
and debris which could contaminate internal compo­nents, or obstruct proper cooling of the power compo­nents resulting in premature over-temperature shut­down.

The recommended cleaning procedure is as follows:

1. Be sure to disconnect the Converterʼs input
cable to remove its input power.

2. Remove the four screws securing the rear louver
panel, and remove the panel to expose the cool­ing tunnel heatsinks. (See Figure 4 below):

3. Holding the unit by the front handles, so the
back is facing down, shake the loose debris out
of the unit. Raking out the heatsink fins may be
necessary for jammed debris.

4. If necessary, remove the case wraparound cover
and using the skid handles to hold upside down
carefully dump out any remaining loose debris,
or carefully blow out using low pressure air.

5. Reassemble the cleaned out Converter by
reversing the above steps.

DIGITAL METER CALIBRATION

If calibration of either digital meter is ever necessary,
meter calibration adjustment trimmers are provided on
the Weld Control PC board inside the Control Module
(see Figure 5). Calibration must be done with an
Output current load, so meters are displaying Actual
(not Preset) values. It is recommended that the cali­bration levels be near the rating plate values, for best
accuracy, and compared to "master" meters with bet­ter than 2% accuracy.

The accuracy of Actual AMPS meter should be within
3% of the welding amps monitored. The AMPS meter
trimmer (R561) is located near the center of the Weld
Control PC board just below the VOLTS meter trim­mer (R562). Clockwise rotation of the trimmer adjust­ment screw will decrease the meter reading.

The accuracy of Actual VOLTS meter should be within
3% of the welding volts monitored. The VOLTS meter
trimmer (R562) is located near the center of the Weld
Control PC board just above the AMPS meter trim­mer (R561). Clockwise rotation of the trimmer adjust­ment screw will decrease the meter reading. The
"master" voltmeter should be connected as close as
possible to the "ELECTRODE +" stud and "WORK-"
lead bolt, for best accuracy.

Figure 4

MULTI-WELD 350

D-2

MAINTENANCE

D-2

SERVICE

The Multi-Weld 350 was designed for easy service
using quick to replace components, and assembly

4

modules which could be simply swapped out at the
job site to minimize down time, and so more pro­longed troubleshooting and repair of the module may
be done later on the service bench.

2

1

3

Figure 5

The above, Figure 5, shows the three assembly modules of the Converter which are covered with the Case
Wraparound (item (4)):

Control Module (item (1) is removed from the Base
Module assembly by removing the two bottom
accessed screws and disconnecting the three sealed
harness plugs from the receptacles on the back of the
Control box.

This module is a sealed enclosure containing replace­able electronic components:

• Sealed back cover which mounts the internal "pot­ted" Control and Peripheral PCBʼs.

• Front panel with "plug-n-play" instruments which
individually plug to the Control PCB.

• Interchangeable "potted" digital meters with front
replaceable spatter shield lenses.

• Harness lead receptacles that connect to Base
Module harness lead plugs.

Tunnel Module (item (2) is removed from the Base
Module assembly by removing the four bottom
accessed screws and disconnecting the two sealed
harness plugs and power leads.
Note: Removal of Control Module improves access to
disconnect Tunnel Module power leads.

This module assembly includes:

• Heatsinked power switching (IGBT) boards and
isolated diodes.

• Capacitors and potted power supply boards.

• Fan and sheetmetal bulkhead tunnel and compo­nent enclosure.

• Harness lead receptacles and power leads that
connect to Base Module.

Base Module (item (3) is the mounting and connec­tion platform for the other modules.

This module assembly includes:

• Base sheetmetal with input / output connection
chambers with "pigtail" leads.

• Input contactor, input diodes heat sink assembly
and work clip lead.

• Output chokes and current shunt.

• Lead harness sealed plugs connect to Tunnel and
Control Module receptacles.

MULTI-WELD 350

E-1

TROUBLESHOOTING

HOW TO USE TROUBLESHOOTING GUIDE

WARNING

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

__________________________________________________________________________

E-1

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.

Step 2. POSSIBLE CAUSE.

The second column labeled “POSSIBLE CAUSE” lists
the obvious external possibilities that may contribute
to the machine symptom.

Step 3. RECOMMENDED COURSE OF ACTION

This column provides a course of action for the
Possible Cause, generally it states to contact your
local Lincoln Authorized Field Service Facility.

If you do not understand or are unable to perform the
Recommended Course of Action safely, contact your
local Lincoln Authorized Field Service Facility.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your

Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.

MULTI-WELD 350

E-2

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

(SYMPTOMS)

TROUBLESHOOTING

POSSIBLE

CAUSE

E-2

RECOMMENDED

COURSE OF ACTION

Machine completely dead:
Input contactor does not pull in,

meters are off.

Meter turns on but input contator
does not pull in.

1. Check Input cable connections for
loose or faulty connection.

2. Input voltage may be too low.

3. The power switch may be faulty.

4. The DC Buss Power Supply PCB

or its connections may be faulty.

5. The Analog Control Power Supply
PCB may be faulty.

6. The Weld Control PCB may be
faulty.

1. Input to high

2. Remote receptacle output switch­ing enabled.

3. The contactor or supply voltage to
contactor coil may be faulty.

If all recommended possible areas of
misadjustment have been checked
and the problem persists, Contact

your local Lincoln Authorized
Field Service Facility.

4. The connections at PCB connec­tors inside the control box may be
faulty.

5. The Peripheral PCB may be
faulty.

6. The Weld Control PCB may be
faulty.

Thermal light comes on.

1. Over- Temperature shut down.

2. The thermostat or imbalance pro­tector or Peak Input Voltage
Protection (if present) or their con­nections may be faulty.

3. Bad analog control Supply PCB.

4. Bad weld control PCB.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your

Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.

MULTI-WELD 350

E-3

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

(SYMPTOMS)

Meter turns on, input contactor
pulls in, thermal light is off.

TROUBLESHOOTING

POSSIBLE

CAUSE

1. The output cable connections may
be faulty.

2. The connections at control box
plugs, chopper boards plugs, or
Analog Control Power Supply PCB
may be faulty.

3. Inputs to Chopper PCB or
Chopper PCB may be faulty.

4. The Analog Control Supply PCB
may be faulty.

5. The connection at PCB connec­tors inside the control box may be
faulty.

6. The Weld Control PCB may be
faulty.

E-3

RECOMMENDED

COURSE OF ACTION

Preset is not adjustable:
Note: Panel control is disabled if
Remote is plugged in.

Preset range is not right:

None of the meters comes on in
CC or CV settings:

Meter comes on in only one of the
CC or CV settings:

1. The output control potentiometer
or its connections may be faulty.

2. The Weld Control board or its con­nections may be faulty.

1. A faulty or missing plug P3 at con­nector J3 of Weld Control PCB.

2. The Weld Control board or its con­nections may be faulty.

1. The Analog Control Power Supply
PCB or its connections may be
faulty.

2. The Weld Control PCB or connec­tions to meters may be faulty.

3. Faulty meters.

1. The Weld Control PCB or connec­tions to meters may be faulty.

If all recommended possible areas
of misadjustment have been
checked and the problem persists,

Contact your local Lincoln
Authorized Field Service Facility.

2. Faulty meters.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your

Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.

MULTI-WELD 350

E-4

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

(SYMPTOMS)

TROUBLESHOOTING

POSSIBLE

CAUSE

E-4

RECOMMENDED

COURSE OF ACTION

The meter is not accurate:

Fan does not run when turning
machine on:

Fan does not run when welding:

No control, very high output cur­rent:

1. The Analog Control Power Supply
PCB or its connections may be
faulty.

2. The Weld Control PCB may be
faulty.

1. Fan does not normally run until
machine is welding. See
Instruction Manual.

1. Faulty Supply voltage to fan.

2. Faulty fan

3. The Weld Control PCB may be
faulty.

1. Input shorts to output.

2. Faulty shunt lead connection.

3. Faulty output control potentiome­ter or its connections.

If all recommended possible areas of
misadjustment have been checked
and the problem persists, Contact

your local Lincoln Authorized
Field Service Facility.

No control, maximum output cur­rent stays around 200A:

No control :

4. Faulty Weld Control PCB.

1.Output shorted

2. Faulty voltage feedback connec­tion.

3. Faulty Weld Control PCB.

1. Faulty output control potentiome­ter or its connections.

2. Faulty connections at Weld
Control PCB connectors.

3. Faulty Weld Control PCB.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your

Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.

MULTI-WELD 350

E-5

Observe all Safety Guidelines detailed throughout this manual

PROBLEMS

(SYMPTOMS)

TROUBLESHOOTING

POSSIBLE

CAUSE

E-5

RECOMMENDED

COURSE OF ACTION

Current changing with arc length
in Stick welding:

Poor performance on "fast-freeze"
type electrodes such as E6010,
E7010:

Bad starting:

1. Check the CC Slope switch on the
recessed panel, it should be set at
Stick/Gauge position for Stick
welding.

2. Faulty CC Slope switch or con­nections.

3. Faulty Weld Control PCB.

1. Check the CC Slope switch on the
recessed panel, it should be set at
Pipe position.

2. Faulty CC Slope switch or con­nections.

3. Faulty connections on Weld
Control PCB connectors.

4. Faulty Weld Control PCB.

1. Adjust Hot Start setting on the
recessed panel.

If all recommended possible areas of
misadjustment have been checked
and the problem persists, Contact

your local Lincoln Authorized
Field Service Facility.

Electrode "stubbing":

2. Check Hot Start potentiometer
and connections. The Hot Start
and Arc Force potentiometers are
interchangeable, switch them to
check out.

1. Adjust Arc Force setting on the
recessed panel.

2. Check Arc Force potentiometer
and connections. The Hot Start
and Arc Force potentiometers are
interchangeable, switch them to
check out.

CAUTION

If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact your

Local Lincoln Authorized Field Service Facility for technical troubleshooting assistance before you proceed.

MULTI-WELD 350

F-1

ENHANCED DIAGRAM

DIAGRAMS

F-1

MULTI-WELD 350

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The specific diagram for a particular code is pasted inside the

machine on one of the enclosure panels. If the diagram is illegible, write to the Service Department for a replacement. Give the equipment code number.

F-2

ENHANCED DIAGRAM

DIAGRAMS

F-2

MULTI-WELD 350

NOTE: This diagram is for reference only. It may not be accurate for all machines covered by this manual. The specific diagram for a particular code is pasted inside the

machine on one of the enclosure panels. If the diagram is illegible, write to the Service Department for a replacement. Give the equipment code number.

F-3

DIAGRAMS

F-3

A

11321

MULTI-WELD 350

MULTI-WELD 350

DIMENSION PRINT - MULTI-WELD 350 CONVERTER

MULTI-WELD 350

F-4

DIAGRAMS

F-4

M19448

C-UF

DIMENSION PRINT FOR DISTRIBUTION BOX

MULTI-WELD 350

G Keep your head out of fumes.
G Use ventilation or exhaust to

remove fumes from breathing zone.

G Turn power off before servicing.

G Do not operate with panel open or

guards off.

WARNING

G Los humos fuera de la zona de res-

piración.

G Mantenga la cabeza fuera de los

humos. Utilice ventilación o
aspiración para gases.

G Gardez la tête à l’écart des fumées.
G Utilisez un ventilateur ou un aspira-

teur pour ôter les fumées des zones
de travail.

G Vermeiden Sie das Einatmen von

Schweibrauch!

G Sorgen Sie für gute Be- und

Entlüftung des Arbeitsplatzes!

G Mantenha seu rosto da fumaça.
G Use ventilação e exhaustão para

remover fumo da zona respiratória.

G Desconectar el cable de ali-

mentación de poder de la máquina
antes de iniciar cualquier servicio.

G Débranchez le courant avant l’entre-

tien.

G Strom vor Wartungsarbeiten

abschalten! (Netzstrom völlig öff­nen; Maschine anhalten!)

G Não opere com as tampas removidas.
G Desligue a corrente antes de fazer

serviço.

G Não toque as partes elétricas nuas.

G No operar con panel abierto o

guardas quitadas.

G N’opérez pas avec les panneaux

ouverts ou avec les dispositifs de
protection enlevés.

G Anlage nie ohne Schutzgehäuse

oder Innenschutzverkleidung in
Betrieb setzen!

G Mantenha-se afastado das partes

moventes.

G Não opere com os paineis abertos

ou guardas removidas.

Spanish

AVISO DE

PRECAUCION

French

ATTENTION

German

WARNUNG

Portuguese

ATENÇÃO

Japanese

Chinese

Korean

Arabic

LEIA E COMPREENDA AS INSTRUÇÕES DO FABRICANTE PARA ESTE EQUIPAMENTO E AS PARTES DE USO, E SIGA AS
PRÁTICAS DE SEGURANÇA DO EMPREGADOR.

WARNING

Spanish

AVISO DE

PRECAUCION

G Do not touch electrically live parts or

electrode with skin or wet clothing.

G Insulate yourself from work and

ground.

G No toque las partes o los electrodos

bajo carga con la piel o ropa moja­da.

G Aislese del trabajo y de la tierra.

G Keep flammable materials away.

G Mantenga el material combustible

fuera del área de trabajo.

G Wear eye, ear and body protection.

G Protéjase los ojos, los oídos y el

cuerpo.

French

ATTENTION

German

WARNUNG

Portuguese

ATENÇÃO

Japanese

Chinese

Korean

Arabic

G Ne laissez ni la peau ni des vête-

ments mouillés entrer en contact
avec des pièces sous tension.

G Isolez-vous du travail et de la terre.

G Berühren Sie keine stromführenden

Teile oder Elektroden mit Ihrem
Körper oder feuchter Kleidung!

G Isolieren Sie sich von den

Elektroden und dem Erdboden!

G Não toque partes elétricas e elec-

trodos com a pele ou roupa molha­da.

G Isole-se da peça e terra.

G Gardez à l’écart de tout matériel

inflammable.

G Entfernen Sie brennbarres Material!

G Mantenha inflamáveis bem guarda-

dos.

G Protégez vos yeux, vos oreilles et

votre corps.

G Tragen Sie Augen-, Ohren- und Kör-

perschutz!

G Use proteção para a vista, ouvido e

corpo.

READ AND UNDERSTAND THE MANUFACTURER’S INSTRUCTION FOR THIS EQUIPMENT AND THE CONSUMABLES TO BE
USED AND FOLLOW YOUR EMPLOYER’S SAFETY PRACTICES.

SE RECOMIENDA LEER Y ENTENDER LAS INSTRUCCIONES DEL FABRICANTE PARA EL USO DE ESTE EQUIPO Y LOS
CONSUMIBLES QUE VA A UTILIZAR, SIGA LAS MEDIDAS DE SEGURIDAD DE SU SUPERVISOR.

LISEZ ET COMPRENEZ LES INSTRUCTIONS DU FABRICANT EN CE QUI REGARDE CET EQUIPMENT ET LES PRODUITS A
ETRE EMPLOYES ET SUIVEZ LES PROCEDURES DE SECURITE DE VOTRE EMPLOYEUR.

LESEN SIE UND BEFOLGEN SIE DIE BETRIEBSANLEITUNG DER ANLAGE UND DEN ELEKTRODENEINSATZ DES HER­STELLERS. DIE UNFALLVERHÜTUNGSVORSCHRIFTEN DES ARBEITGEBERS SIND EBENFALLS ZU BEACHTEN.

• World's Leader in Welding and Cutting Products •

• Sales and Service through Subsidiaries and Distributors Worldwide •

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