Lincoln Electric SQUARE WAVE TIG 255 SVM100-A Manual Do Utilizador

Observe Safety Guidelines
detailed in the beginning of this manual.

Machine output is intermittently
lost.  Gas flow and high frequency
are also interrupted.

Arc “Flutters” when TIG welding.

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.

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.

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.

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.