PC Board Troubleshooting Procedures

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TROUBLESHOOTING AND REPAIR

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WARNING

- Remove the PC board from the static-shielding bag

and place it directly into the equipment. Donʼt set the

ELECTRIC SHOCK

PC board on or near paper, plastic or cloth which

can kill.

could have a static charge. If the PC board canʼt be

•

Have

an electrician install and

installed immediately, put it back in the static-shield-

ing bag.

service this equipment. Turn the

- If the PC board uses protective shorting jumpers,

input

power OFF at the fuse box

before working on equipment. Do

donʼt remove them until installation is complete.

not touch electrically hot parts.

- If you return a PC board to The Lincoln Electric

Company for credit, it must be in the static-shielding

CAUTION

bag. This will prevent further damage and allow prop-

er failure analysis.

Sometimes machine failures appear to be due to PC

4. Test the machine to determine if the failure

board failures. These problems can sometimes be

symptom has been corrected by the

traced to poor electrical connections. To avoid prob-

replacement PC board.

lems when troubleshooting and replacing PC boards,

NOTE: It is desirable to have a spare (known good)

please use the following procedure:

PC board available for PC board troubleshooting.

1. Determine to the best of your technical ability

NOTE: Allow the machine to heat up so that all

that the PC board is the most likely component

causing the failure symptom.

electrical components can reach their operating

2. Check for loose connections at the PC board

temperature.

5. Remove the replacement PC board and

to assure that the PC board is properly

substitute it with the original PC board to

connected.

recreate the original problem.

3. If the problem persists, replace the suspect PC

a. If the original problem does not reappear by

board using standard practices to avoid static

substituting the original board, then the PC

electrical damage and electrical shock. Read

board was not the problem. Continue to look

the warning inside the static resistant bag and

for bad connections in the control wiring

perform the following procedures:

harness, junction blocks, and terminal strips.

PC board can be damaged by static electricity.

b. If the original problem is recreated by the

- Remove your bodyʼs static

substitution of the original board, then the PC

charge before opening the static-

board was the problem. Reinstall the

shielding bag. Wear an anti-static

replacement PC board and test the machine.

wrist strap. For safety, use a 1

6. Always indicate that this procedure was

ATTENTION

Meg ohm resistive cord connected

followed when warranty reports are to be

to a grounded part of the

submitted.

Static-Sensitive

equipment frame.

NOTE: Following this procedure and writing on the

Devices

- If you donʼt have a wrist strap,

Handle only at

touch an un-painted, grounded,

warranty report, “INSTALLED AND SWITCHED PC

Static-Safe

part of the equipment frame. Keep

BOARDS TO VERIFY PROBLEM,” will help avoid

Workstations

touching the frame to prevent

denial of legitimate PC board warranty claims.

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.

Lincoln Electric SVM194-A service manual PC Board Troubleshooting Procedures, Electric Shock

Models: SVM194-A

TROUBLESHOOTING AND REPAIR