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TROUBLESHOOTING & REPAIR
F-5
F-5
SQUARE WAVE TIG 275
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
CAUTION
If for any reason you do not understand the test procedures or are unable to perform the test/repairs safely, con-
tact the Lincoln Electric Service Department for electrical troubleshooting assistance before you proceed. Call 216-
383-2531 or 1-800-833-9353.
PROBLEMS
(SYMPTOMS)
POSSIBLE AREAS OF
MISADJUSTMENT(S)
RECOMMENDED
COURSE OF ACTION
OUTPUT PROBLEMS
No welding output. The 115 VAC is
present at the receptacle. (220
VAC receptacle on European mod-
els only).
1. Make sure the polarity switch is
in the proper position and func-
tioning correctly.
2. One of the thermostats may be
tripped. Allow the machine to
cool. The thermal light will be
on.
3. Make sure the welding cables,
torch and connections are in
good operating condition.
1. Check for loose or faulty con-
nections on the heavy current
carrying leads. (Polarity switch,
output choke, output terminals,
etc.)
2. Check for faulty connections or
a defective thermostat. Check
leads #313, #314,.#315 and
#316. See the Wiring Diagram.
The thermal light will be on.
3. Perform the
T1 Transformer
Test.
4. Perform the
SCR Bridge Test.
5. Check the current control R1 for
proper operation. Normal resis-
tance is 10,000 ohms. Also
check associated leads for
loose or faulty connections.
6. The control board may be faulty.