Lincoln Electric Cross Country 300 Service Manual page 57

LINCOLN ELECTRIC
12. If the voltage drops to 0 VDC after the leads 23 and plug J3 have been disconnected, the weld
control board is driving the chopper module when it should not be doing so. Reconnect lead 23 and
plug J3 and perform the Weld Control Board PWM Gate Signal Test Procedure.
13. Reconnect leads 23 and plug J3. See Wiring Diagram.
14. Check for about 58 VDC between chopper module terminals B2+ to B3- and B5+ to B6 and across
the welder output terminals. See Figure F.20. See Wiring Diagram.
15. If about 58 VDC is present at chopper module terminals B2+ to B3- and B5+ to B6-, but not at the
weld output terminals, there is a problem between the chopper module and one of the output
terminals. Check for damaged conductors or faulty connections. Also check the shunt, the choke
and the connections at the back of the output terminals. See Wiring Diagram.
16. If the voltage at terminals B2+ to B3- and B5+ to B6- of the chopper module is significantly higher
than 58 VDC, check for an open R4 load resistor. See Wiring Diagram.
17. If the voltage at terminals B2+ to B3- and B5+ to B6- of the chopper module are very low or not
present, use the frequency counter to check for the presence of a 20 kHz PWM signal between leads
23 +and plug J3, where they connect to the chopper module board.
18. If the 20 kHz signal is present, the chopper module is defective. Perform the Chopper Module PC
Board Removal And Replacement Procedure.
19. If the 20 kHz signal is not present, perform the Weld Control Board PWM Gate Signal Test
Procedure.
20. If the weld control board is producing a PWM gate signal, check lead 23 and plug J3 for damaged
conductors and faulty connections between the weld control board and the chopper module board.
21. If testing is complete, perform the Case Cover Replacement Procedure.
LED
1
2
3
Table F. 6 – Chopper module LED tests
COLOR
GREEN
GREEN
GREEN
Cross Country™ 300 Service Manual
INDICATION
PWM INPUT PRESENT
15 VDC POWER SUPPLY PRESENT
CHOPPER OUTPUT PRESENT
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