Lincoln Electric INVERTEC V275-S Service Manual page 33

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PC BOARD TROUBLESHOOTING PROCEDURES
WARNING
ELECTRIC SHOCK can kill.
*Have an electrician install and service
this equipment.
OFF before working on equipment.
Do not touch electrically hot parts.
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 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 Boards 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
ATTENTION
ohm resistive cord connected to a
Static-Sensitive
grounded part of the equipment
Devices
frame.
Handle only at
Static-Safe
• If you don't have a wrist strap,
Workstations
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 conductive, anti-static or static-dissipative.
TROUBLESHOOTING & REPAIR
Turn the machine
V275-S
• 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-shield-
ing bag. This will prevent further damage and
allow proper 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 elec-
trical components can reach their operating
temperature.
5. Remove the replacement PC Board and substitute
it with the original PC Board to recreate the origi-
nal 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.
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