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TROUBLESHOOTING & REPAIR
F-12 F-12
SQUARE WAVE TIG 355
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
TIG MODE PROBLEMS
No high frequency. Machine is in
TIG Mode and has normal output.
1. In order for the high frequency
to operate, the machine must
be either in Start Only mode or
Continuous High Frequency
mode.
2. The high frequency spark gap
may be too large or shorted.
Check the gap per mainte-
nance instructions.
1. Check the high voltage trans-
former (T3). The normal resis-
tance of the secondary wind-
ing is 12.5 k-ohms.
115VAC is applied to the pri-
mary of T3. A very high volt-
age is developed on the sec-
ondary winding. For assis-
tance call the Lincoln Electric
Service Dept., (216) 383-2531
or 1-800-833-9353 (WELD).
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 Board
High Frequency Signal Test.
6. The power board may be
faulty. Replace.