Lincoln Electric Understanding Lincoln Chopper Technology: A Guide to Troubleshooting and Repair

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F-63	TROUBLESHOOTING & REPAIR	F-63
	CHOPPER MODULE FUNCTION TEST (continued)

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TEST PROCEDURE (CONTINUED)

13.If about 58 VDC is present at chopper mod- ule terminals B2+ to B3-, and B5+ to B6-, but not at the output terminals, there is a problem between the chopper module and one of the output terminals. Check for damaged con- ductors or faulty connections, on leads W7, W8, W9, and W10. Also check the shunt, the choke, and the connections at the back of the output terminals. See the wiring diagram.

14.If the voltage at terminals B2+ to B3-, and B5+ to B6- of the Chopper module is signifi- cantly higher than 58 VDC, check for an open R4 load resistor. See the Control Inner- Connection diagram. Also check for dam- aged conductors or faulty connections at leads #302 and #302. See wiring diagram.

15.If the voltage at terminals B2+ to B3-, and B5+ to B6- of the chopper module is very low, or not present, use the frequency counter to check for the presents of a 20 kHZ PWM sig- nal between leads #23 +and #25-, where they connect to the chopper module PC board.

16.If the 20 kHz signal is present, the chopper module is defective. Replace.

17.If the 20 kHz signal is not present, perform

the Weld. Control Board PWM Gate Drive

Test

18.If the weld control board is producing a PWM gate signal, check th e#23 and #25 leads for damaged conductors and faulty connections between the control PC board and the chop- per module.

19.If testing is complete, Perform the

procedure. CaseCover Replacement

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RANGER 305D