Lincoln Electric PRECISION TIG 275 IM702-A Operator's Manual page 37

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Observe all Safety Guidelines detailed throughout this manual
PROBLEMS
(SYMPTOMS)
Arc "pulsates" in AC polarity, DC
polarity is o.k.
Black area along weld bead
Output quits momentarily; gas flow
and hi-freq are also interrupted
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.
TROUBLESHOOTING
POSSIBLE
CAUSE
TIG PROBLEMS
1.Micro switch S2A on polarity switch
does not open in AC polarity
1. Oily or organic contamination from
work piece
2. Tungsten electrode may be conta-
minated
3. Leaks in gas line, torch, or con-
nections
1. May be caused by hi-freq interfer-
ence. Check that machine is
grounded properly. Surrounding
machines that generate hi-freq
also should be properly grounded.
2. Ground connection of Protection
PC board may has become loose
3. Ground connection
Bypass/Stabilizer PC board may
has become loose.
CAUTION
PRECISION TIG 275
RECOMMENDED
COURSE OF ACTION
If all recommended possible areas
of
of misadjustment
checked and the problem persists,
Contact your local
Authorized Field Service Facility.
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have been
Lincoln