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SQUARE WAVE TIG 255
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F-10
TROUBLESHOOTING & REPAIR
Observe Safety Guidelines
detailed in the beginning of this manual.
TROUBLESHOOTING GUIDE
PROBLEMS
(SYMPTOMS)
Machine output is intermittently
lost. Gas flow and high frequency
are also interrupted.
Arc “Flutters” when TIG welding.
POSSIBLE AREAS OF
MISADJUSTMENT(S)
1. Problem may be caused by
high frequency interference.
Make sure that the machine is
grounded properly according
to the installation instructions.
If there are other high
frequency sources in the area,
make certain that they are
grounded properly.
2. Check arc start switch or
amptrol for proper operation
and loose connections.
1. Tungsten electrode may be
too large in diameter.
2. Tungsten not “Sharp” when
welding in DC negative mode.
3. If helium is used as a
shielding gas, then reduce the
percentage of helium.
4. Adjust flow rate of shielding
gas.
5. Check hoses and connections
for leaks.
RECOMMENDED
COURSE OF ACTION
1. Internal ground connections
may be loose. Check mounting
screws on the Protection/
Snubber board and also on the
Bypass board. All case screws
should be in place and tight.
2. Protection/Snubber board may
be faulty. See Protection/
Snubber Board Continuity Test.
3. Check trigger circuit. See Arc
Start Trigger Circuit Test.
1. Check for loose shunt connec-
tions.- leads #221 and #222.
Refer to wiring diagram.
2. Check polarity switch for loose
or faulty connections.
3. SCR bridge may be faulty. See
Static and Active SCR Tests.
4. Protection/Snubber board may
be faulty. See Protection/
Snubber Board Continuity Test.
5. Check R3, R4 and C2 in the
high voltage transformer prima-
ry circuit. Refer to wiring dia-
gram.
6. The Control board may be
faulty.-Replace.
TIG MODE PROBLEMS
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 216-383-2531 or 1-800-833-9353.
CAUTION