Lincoln Electric POWER MIG SVM170-A Service Manual page 46

F-6
Observe all Safety Guidelines detailed throughout this manual.
PROBLEMS
(SYMPTOMS)
The output voltage and wire feed is
present continuously or pulsing
when gun trigger is NOT activated.
The output voltage is present contin-
uously when gun trigger is NOT acti-
vated.
If for any reason you do not understand the test procedures or are unable to perform the tests/repairs safely, contact the Lincoln Electric
Service Department for technical troubleshooting assistance before you proceed. Call 1-888-935-3877.
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TROUBLESHOOTING AND REPAIR
POSSIBLE AREAS OF
MISADJUSTMENT(S)
OUTPUT PROBLEMS (Continued)
1. Remove the gun. If the problem
is resolved the gun trigger circuit
is faulty. Repair or replace.
2. If problem persists when gun
assembly is removed from
machine, then the problem is
within the POWER MIG 255C.
Contact your local Lincoln Electric
Authorized Field Service Facility.
CAUTION
POWER MIG 255C
RECOMMENDED
COURSE OF ACTION
1. Check the machine's internal
trigger leads for grounds or
shorts. See Wiring Diagram.
2. The control board may be faulty.
Replace.
1. Perform the SCR Rectifier
Assembly Tests.
2. The control board may be faulty.
Replace.
F-6