Lincoln Electric SVM188-A Troubleshooting and Repair, PC Board Troubleshooting Procedures

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F-3	TROUBLESHOOTING AND 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 electrically hot par ts.

CAUTION

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

-If the PC board uses protective shorting jumpers, don’t 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 deter mine if the failure s y m p t o m h a s b e e n c o r r e c t e d by t h e 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.R e m ove t h e r e p l a c e m e n t P C b o a r d a n d s u b s t i t u t e i t w i t h t h e o r i g i n a l P C b o a r d t o 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 wir ing harness, junction blocks, and terminal strips.

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ATTENTION

Static-Sensitive

Devices

Handle only at

Static-Safe

Workstations

-R e m ove yo u r b o d y ’s s t a t i c 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 par t of the equipment frame.

-If you don’t have a wrist strap, touch an un-painted, grounded, part of the equipment frame. Keep t o u c h i n g t h e f ra m e t o p r eve n t s t a t i c bu i l d - u p. B e s u r e n o t t o touch any electrically live parts at the same time.

b. If the original problem is recreated by the substitution of the original board, then the PC b o a r d wa s t h e p r o bl e m . R e i n s t a l l t h e replacement PC board and test the machine.

6.A l way s i n d i c a t e t h a t t h i s p r o c e d u r e wa s fo l l owe d w h e n wa r ra n t y r e p o r t s a r e t o b e 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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-Tools which come in contact with the PC board must be either conductive, anti-static or static-dissipative.

DC-600