Lincoln Electric Ranger 305D Service Manual page 117

F-63
CHOPPER MODULE FUNCTION TEST ( ontinued)
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.
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.
TROUBLESHOOTING & REPAIR
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See the Control Inner-
RANGER 305D
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
18. If the weld control board is producing a PWM Test.
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 Case
Cover Replacement procedure.
F-63