Lincoln Electric SVM123-A service manual PC Board Troubleshooting Procedures

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F-3

TROUBLESHOOTING & REPAIR F-3

PC BOARD TROUBLESHOOTING PROCEDURES

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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 elec- trically hot parts.

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CAUTION: Sometimes machine failures appear to be due to PC board failures. These problems can sometimes be traced to poor electrical connections. To avoid problems when troubleshooting and replacing PC boards, please use the following pro- cedure:

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 connect- ed.

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:

P.C. Board can be damaged by static electricity.

-Remove the P.C. Board from the static-shielding bag and place it directly into the equipment. Don’t set the P.C. Board on or near paper, plastic or cloth which could have a static charge. If the P.C. Board can’t be installed immediately, put it back in the static-shielding bag.

-If the P.C. Board uses protective shorting jumpers, don’t remove them until installation is complete.

-If you return a P.C. 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 symptom has been corrected by the replace- ment PC board.

NOTE: It is desirable to have a spare (known good) PC board available for PC board trou- bleshooting.

NOTE: Allow the machine to heat up so that all electrical components can reach their operating temperature.

5. Remove the replacement PC board and sub-
stitute it with the original PC board to recreate
the original problem.
a.	If the original problem does not reap-
	pear by substituting the original board,
	then the PC board was not the prob-
	lem. Continue to look for bad connec-

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ATTENTION

Static-Sensitive

Devices

Handle only at

Static-Safe

Workstations

Reusable

Container

Do Not Destroy

-Remove your body’s 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 equip- ment frame.

-If you don’t have a wrist strap, touch an unpainted, grounded, part of the equip- ment frame. Keep touching the frame to prevent static build-up. Be sure not to touch any electrically live parts at the same time.

	tions 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 fol-
lowed when warranty reports are to be submit-
ted.

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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-Tools which come in contact with the P.C. Board must be either conductive, anti-static or static-dissi- pative.

IDEALARC DC-1000