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ELECTRIC SHOCK can kill.
Have an electrician install and service
this equipment. Turn the input power
OFF at the fuse box before working on
equipment. Do not touch electrically hot
parts.
CAUTION: Sometimes machine failures appear to be
due to PC board failures. These problems can some-
times be traced to poor electrical connections. To avoid
problems when troubleshooting and replacing PC
boards, please use the following procedure:
1.
Determine to the best of your technical ability that
the PC board is the most likely component causing
the failure symptom.
2.
Check for loose connections at the PC board to
assure that the PC board is properly connected.
3.
If the problem persists, replace the suspect PC
board using standard practices to avoid static elec-
trical damage and electrical shock. Read the warn-
ing inside the static resistant bag and perform the
following procedures:
PC Board can be damaged by static electricity.
• Remove your body’s static charge
before opening the static-shield-
ing bag. Wear an anti-static wrist
strap. For safety, use a 1 Meg
ohm resistive cord connected to a
grounded part of the equipment
frame.
• If you don’t have a wrist strap,
touch an unpainted, grounded,
part of the equipment frame.
Keep touching the frame to pre-
vent static build-up. Be sure not
to touch any electrically live parts
at the same time.
• Tools which come in contact with
the PC Board must be either con-
ductive, anti-static or static-dissi-
pative.
• Remove the PC Board from the static-shielding bag
and place it directly into the equipment. Don’t set the
PC Board on or near paper, plastic or cloth which
could have a static charge. If the PC Board can’t be
installed immediately, put it back in the static-shielding
bag.
• If the PC Board uses protective shorting jumpers,
don’t remove them until installation is complete.
• If you return a PC Board to The Lincoln Electric
Company for credit, it must be in the static-shielding
bag. This will prevent further damage and allow prop-
er failure analysis.
4.
Test the machine to determine if the failure symp-
tom has been corrected by the replacement PC
board.
NOTE: It is desirable to have a spare (known good) PC
board available for PC board troubleshooting.
NOTE: Allow the machine to heat up so that all electri-
cal components can reach their operating temperature.
5.
Remove the replacement PC board and substitute
it with the original PC board to recreate the original
problem.
a. If the original problem does not reappear
by substituting the original board, then the
PC board was not the problem. Continue
to look for bad connections in the control
wiring harness, junction blocks, and termi-
nal strips.
b. If the original problem is recreated by the
substitution of the original board, then the
PC board was the problem. Reinstall the
replacement PC board and test the
machine.
6.
Always indicate that this procedure was followed
when warranty reports are to be submitted.
NOTE:
Following this procedure and writing on the
warranty report, “INSTALLED AND SWITCHED PC
BOARDS TO VERIFY PROBLEM,” will help avoid
denial of legitimate PC board warranty claims.
TROUBLESHOOTING & REPAIR
F-3
F-3
SQUARE WAVE TIG 275
PC BOARD TROUBLESHOOTING PROCEDURES
WARNING
ATTENTION
Static-Sensitive
Devices
Handle only at
Static-Safe
Workstations
Reusable
Container
Do Not Destroy
