Lincoln Electric INVERTEC 270SX Service Manual page 21

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
•
Prior to performing preventive maintenance,
perform the following capacitor discharge
procedure to avoid electric shock
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
caus-ing the failure symptom.
2. Check for loose connections at the PC board
toassure 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.
4. Test the machine to determine if the failure
symp-tom has been corrected by the
replacement PC board.
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.
•
•
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.
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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.
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.