Pc Board Troubleshooting Procedures - Lincoln Electric X-TRACTOR 1GC Service Manual

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X-TRACTOR 1GC

PC BOARD TROUBLESHOOTING PROCEDURES

WARNING
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 sometimes be traced to poor
electrical connections. To avoid problems when trouble-
shooting 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 electrical damage and electrical
shock. Read the warning 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-
shielding 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 un-painted, grounded, part
of the equipment frame. Keep touching the frame to prevent 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 conductive, anti-static
or static-dissipative.
• 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
ATTENTION
have a static charge. If the PC board can't
Static-Sensitive
be installed immediately, put it back in the
Devices Handle
static-shielding bag.
only at Static-Safe
• If the PC board uses protective shorting
Workstations
jumpers, don't remove them until
installation is complete.
Reusable
• If you return a PC board to The Lincoln
Container
Electric Company for credit, it must be in
Do Not Destroy
the static-shielding bag. This will prevent
further damage and allow proper failure
analysis.
4. Test the machine to determine if the failure symptom 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 electrical 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 terminal
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.
F-3
TROUBLESHOOTING AND REPAIR