Troubleshooting & repair, Pc board troubleshooting procedures, Warning caution – Lincoln Electric V155-S User Manual

Page 35

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TROUBLESHOOTING & REPAIR

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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.

- Remove your bodyʼs static

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 donʼt have a wrist strap,

touch an un-painted, grounded,

part of the equipment frame. Keep

touching the frame to prevent

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.

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.

- 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-shield-

ing 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

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 troubleshooting.
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.
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

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.

PC BOARD TROUBLESHOOTING PROCEDURES

ATTENTION

Static-Sensitive

Devices

Handle only at

Static-Safe

Workstations

WARNING

CAUTION

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