Lincoln Electric SQUARE WAVE TIG 355 Service Manual page 66

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Observe Safety Guidelines detailed in the beginning of this manual.
PROBLEMS
(SYMPTOMS)
No high frequency. Machine is in
TIG Mode and has normal output.
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.
TROUBLESHOOTING AND REPAIR
POSSIBLE AREAS OF
MISADJUSTMENT(S)
TIG MODE PROBLEMS
1. In order for the high frequency to
operate, the machine must be
either in Start Only mode or
Continuous
mode.
2. The high frequency spark gap
may be too large or shorted.
Check the gap per maintenance
instructions.
CAUTION
SQUARE WAVE TIG 355
1. Check the high voltage trans-
former (T3). The normal resis-
tance of the secondary winding
High Frequency is 12.5 k ohms.
applied to the primary of T3. A
very high voltage is developed
on the secondary winding. For
assistance call the Lincoln
Electric Service Dept., 1-888-
935-3877.
2. Check the values of R6 and C6.
Replace if necessary.
3. Check the continuity of coils L4
and L5. Normal resistance is
approximately 10 ohms.
4. Perform the Feed – Thru
Board Test.
5. Perform the Control PC Board
Test.
6. The power board may be faulty.
Replace.
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RECOMMENDED
COURSE OF ACTION
115VAC is