Lincoln Electric SVM168-B service manual PC Board Troubleshooting Procedures, Electric Shock

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	F-3		TROUBLESHOOTING & REPAIR			F-3
		PC BOARD TROUBLESHOOTING PROCEDURES
				- Remove the PC board from the static-shielding bag
		WARNING
				and place it directly into the equipment. Donʼt set the
				PC board on or near paper, plastic or cloth which
		ELECTRIC SHOCK
		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,					It is desirable to have a spare (known good)
please use the following procedure:				NOTE:
	1. Determine to the best of your technical ability			PC board available for PC board troubleshooting.
				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 to			temperature.
				5. Remove the replacement PC board and
	assure that the PC board is properly connected.			substitute it with the original PC board to
	3. If the problem persists, replace the suspect PC			recreate the original problem.
	board using standard practices to avoid static			a. If the original problem does not reappear by
	electrical damage and electrical shock. Read				substituting the original board, then the PC
	the warning inside the static resistant bag and				board was not the problem. Continue to look
	perform the following procedures:				for bad connections in the control wiring
PC board can be damaged by static electricity.					harness, junction blocks, and terminal strips.
		- Remove your bodyʼs static		b. If the original problem is recreated by the
		charge before opening the static-			substitution of the original board, then the PC
		shielding bag. Wear an anti-static			board was the problem. Reinstall the
		wrist strap. For safety, use a 1			replacement PC board and test the machine.
		Meg ohm resistive cord connected		6. Always indicate that this procedure was
		to a grounded part of the		followed when warranty reports are to be
	ATTENTION	equipment frame.		submitted.
	Static-Sensitive	- If you donʼt have a wrist strap,		NOTE:	Following this procedure and writing on the
	Devices
	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
		touching the frame to prevent		denial of legitimate PC board warranty claims.
	Workstations	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.

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