Lincoln Electric Cross Country 300 Service Manual page 66

LINCOLN ELECTRIC
11. Locate plugs J3 and J6 on the weld control board. See Figure F.26. Remove the plugs and check for
dirt, corrosion, damaged, expanded or incorrectly positioned terminals. Repair or replace wiring
components as needed and reconnect the plugs to the control board.
12. Restart the machine and apply a load across the weld terminals that measures about 200 amps. If
the machine will not produce 200 amps of current, apply as much load as you can.
13. Using the voltmeter, measure and note the DC voltage at the weld output terminals.
14. Check the voltage between lead 204S+ (J6-1) and lead 208A- (J3-15) at the weld control board
Molex plugs. The voltage should be the same as was measured at the weld terminals. See Figures
F.26 and F.27.
15. If the voltage readings are different, check the wiring and connections between the welding
terminals and the weld control board. See the Wiring Diagram.
16. Connect the millivolt meter probes between lead 206S+ (J6-2) and lead 204S- (J6-1). See Wiring
Diagram. See Figures F.26 and F.27. If the machine is currently producing 200 amps the millivolt
meter should read about 25 millivolts.
17. If the machine cannot produce 200 amps of weld current, the correct millivolt signal will need to be
calculated by dividing the reading displayed on the external ammeter by 8. See the following
explanation.
The shunt used in this machine will produce 50 millivolts at a load of 400 amps, or 8 amps per
millivolt.
To calculate the correct millivolt signal for a given load, you divide the number of amps displayed on
the ammeter by 8.
Example: If your ammeter reads 75, (75/8 = 9.4) If the shunt is working correctly, and the wiring
between the shunt and the control PC board is in good condition, the meter connected at the
control PC board should be reading about 9.4 millivolts.
18. If the millivolt reading is incorrect, check the wiring between the shunt and the control PC board for
damage, grounds, and faulty connections. If the wiring is good, the shunt and lead assembly is faulty
and should be replaced.
19. Perform the Case Cover Replacement Procedure.
Cross Country™ 300 Service Manual
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