Pc board troubleshooting procedures, Troubleshooting and repair, Warning caution – Lincoln Electric LN-25 SVM114-C User Manual
Page 41
LN-25™
TROUBLESHOOTING AND REPAIR
F-3
F-3
Sometimes machine failures appear to be due to PC
board failures. These problems can sometimes be
traced to poor electrical connections. To avoid prob-
lems 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
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.
-
R e m ove
yo u r
b o d y ’s
s t a t i c
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 par t of the equipment
frame.
- If you don’t have a wrist strap,
touch an un-painted, grounded,
part of the equipment frame. Keep
t o u c h i n g t h e f ra m e t o p r eve n t
s t a t i c bu i l d - u p. B e s u r e n o t t o
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.
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 par ts.
- 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-shield-
ing 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 deter mine if the failure
s y m p t o m
h a s
b e e n
c o r r e c t e d
by
t h e
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. R e m ove t h e r e p l a c e m e n t P C b o a r d a n d
s u b s t i t u t e i t w i t h t h e o r i g i n a l P C b o a r d t o
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
b o a r d
wa s
t h e
p r o bl e m . R e i n s t a l l
t h e
replacement PC board and test the machine.
6. A l way s i n d i c a t e t h a t t h i s p r o c e d u r e wa s
fo l l owe d w h e n wa r ra n t y r e p o r t s a r e t o b e
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.
PC BOARD TROUBLESHOOTING PROCEDURES
ATTENTION
Static-Sensitive
Devices
Handle only at
Static-Safe
Workstations
WARNING
CAUTION