Lincoln Electric SVM175-A Troubleshooting & Repair, PC Board Troubleshooting Procedures, 3F-3

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F-3F-3

TROUBLESHOOTING & REPAIR

PC BOARD TROUBLESHOOTING PROCEDURES

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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
	ATTENTION	frame.
	Static-Sensitive	• If you donʼt have a wrist strap,
	Devices
	Handle only at	touch an unpainted, grounded,
	Static-Safe	part of the equipment frame.
	Workstations	Keep touching the frame to pre-
		vent static build-up. Be sure not
	Reusable	to touch any electrically live parts
		at the same time.
	Container	• Tools which come in contact with
	Do Not Destroy	the PC Board must be either con-
		ductive, anti-static or static-dissi-
		pative.

• 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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