If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely,
contact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call
1-800-833-9353.

PROBLEMS
(SYMPTOMS)

POSSIBLE AREAS OF
MISADJUSTMENT(S)

RECOMMENDED
COURSE OF ACTION

OUTPUT PROBLEMS

Wire feeds but welding output is
low causing wire to “stub”. Welds
are “cold”. Machine cannot obtain
full rated output of 300 amps at 32
volts.

1. Make sure that the proper wire

and procedures are being used.

2. Check gun and work cable for

loose or faulty connections.

1. Check for loose or faulty con-

nections of the heavy current
carrying leads. See Wiring
Diagram

2. Perform the

3. Perform

4. Perform the

5. The Control Board may be faulty.

Replace.

The output voltage and wire feed is
present continuously or pulsing
when gun trigger is NOT activated.

1. Remove the gun. If the problem

is resolved, the gun trigger cir-
cuit is faulty. Repair or replace.

2. If problem persists when gun

assembly is removed from
machine, then the problem is
within the POWER MIG 300.

1. Find J85 on Feed Head Board

and unplug. If the problem still
exist Feed Head Board may be
faulty.

The output voltage is present con-
tinuously when gun trigger is NOT
activated. The wire is not feeding.

1. Find J6 on Control PCB and

unplug. If output voltage is not
present change Control PCB

2. Perform the

Chopper Board

Test.

CAUTION

Observe Safety Guidelines
detailed in the beginning of this manual.

TROUBLESHOOTING GUIDE

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