Pc Board Troubleshooting Procedures - Lincoln Electric IDEALARC SP-250 Service Manual

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PC BOARD TROUBLESHOOTING PROCEDURES

CAUTION:
appear to be due to PC board failures. These
problems can sometimes 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 abil-
ity that the PC board is the most likely com-
ponent causing the failure symptom.
2. Check for loose connections at the PC
board to assure that the PC board is proper-
ly 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 pro-
cedures:
ATTENTION
Static-Sensitive
Devices
Handle only at
Static-Safe
Workstations
Reusable
Container
Do Not Destroy
ment 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 P.C.
Board must be either conductive, anti-static or
static-dissipative.
TROUBLESHOOTING & REPAIR
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.
Sometimes machine failures
P.C. Board can be dam-
aged by static electricity.
- Remove your body's stat-
ic 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 unpainted,
grounded, part of the equip-
IDEALARC SP-250
- Remove the P.C. Board from the static-
shielding bag and place it directly into the
equipment. Don't set the P.C. Board on or near
paper, plastic or cloth which could have a sta-
tic charge. If the P.C. Board can't be installed
immediately, put it back in the static-shielding
bag.
- If the P.C. Board uses protective shorting
jumpers, don't remove them until installation is
complete.
- If you return a P.C. Board to The Lincoln
Electric Company for credit, it must be in 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 trou-
bleshooting.
NOTE: Allow the machine to heat up so that
all electrical components can reach their oper-
ating 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 fol-
lowed when warranty reports are to be sub-
mitted.
NOTE: Following this procedure and writing
on the warranty report, "INSTALLED AND
SWITCHED PC BOARDS TO VERIFY PROB-
LEM," will help avoid denial of legitimate PC
board warranty claims.
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