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SQUARE WAVE TIG 255
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F-13
TROUBLESHOOTING & REPAIR
TROUBLESHOOTING GUIDE
Observe Safety Guidelines
detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
High frequency “Spark” is present
at tungsten electrode, but operator
is unable to establish a welding arc.
Machine has normal open circuit
voltage (approximately 53V).
No high frequency. Machine is
in the TIG Mode and has normal
output.
POSSIBLE AREAS OF
MISADJUSTMENT(S)
1. Torch may be faulty.
2. If an amptrol is not being used,
then the machine must be in
the Local Control Mode.
3. Tungsten electrode may be
too large for the process.
4. If helium shielding gas is being
used, then reduce percentage
of helium.
5. If TIG welding in the DC
negative
mode, then a properly
sharpened thoriated tungsten
should be used.
6. Check the welding cables and
output stud connections.
1. In order for the high frequency
to operate, the machine must
be either in the start only
Mode or the continuous high
frequency mode.
2. The high frequency spark gap
may be too large or shorted.
Check gap as per
maintenance instructions.
RECOMMENDED
COURSE OF ACTION
This may be a welding procedure
problem.
Contact The Lincoln Electric
Service Department (216) 383-
2531 or 1-800-833-9353 (WELD).
1. Check the high voltage trans-
former (T3). The normal resis-
tance of the secondary winding
of the high voltage transformer
is 12.5k ohms. 115vac is
applied to the primary of T3. A
very high voltage is developed
on the secondary winding. For
assistance call The Lincoln
Electric Service Department.
(216) 383-2531 or 1-800-833-
9353 (WELD).
2. Check the values of R3, R4
and C2. Replace if faulty.
3. The Protection/Snubber board
may be faulty. See
Protection/Snubber Board
Continuity Test.
4. The Control board may be
faulty. Replace.
TIG WELDING 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