Pc Board Troubleshooting Procedures - Lincoln Electric Ranger 305D Service Manual

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WARNING
ELECTRIC SHOCK can kill.
Have an electrician install and service
this equipment. Turn the machine 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 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 elec-
trical damage and electrical shock. Read the warn-
ing inside the static resistant bag and perform the
following procedures:
PC Board can be damaged by static electricity.
• Remove your bodyʼs static charge
before opening the static-shield-
ing 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.
ATTENTION
Static-Sensitive
• If you donʼt have a wrist strap,
Devices
touch an unpainted, grounded,
Handle only at
part of the equipment frame.
Static-Safe
Keep touching the frame to pre-
Workstations
vent static build-up. Be sure not
to touch any electrically live parts
at the same time.
Reusable
Container
• Tools which come in contact with
Do Not Destroy
the PC Board must be either con-
ductive, anti-static or static-dissi-
pative.
TROUBLESHOOTING & REPAIR
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PC BOARD TROUBLESHOOTING PROCEDURES

RANGER 305D
• Remove the PC Board from the static-shielding bag
and place it directly into the equipment. Donʼt set the
PC Board on or near paper, plastic or cloth which
could have a static charge. If the PC Board canʼt be
installed immediately, put it back in the static-shielding
bag.
• If the PC Board uses protective shorting jumpers,
donʼt 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 determine if the failure symp-
tom has been corrected by the replacement PC
board.
NOTE: Allow the machine to heat up so that all elec-
trical components can reach their operating tempera-
ture.
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 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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