Lincoln Electric SVM175-A - page 130

TROUBLESHOOTING & REPAIR
F-76 F-76
RANGER 305D
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CONTROL POTENTIOMETER AND MODE SWITCH RESISTANCETEST
(continued)
TEST PROCEDURE
1. Turn the engine off
2. Perform the Case cover Removal
Procedure.
3. Unplug P7 from control board, see control
Inner-connection diagram, and visually check
theplug and attached wiring for damage, cor-
rosion, improperly seated or damaged con-
tact pins. P7 will remain unplugged for fol-
lowing test.
4. Set the mode switch in the “CC-Stick” posi-
tion.
5. Test the resistance between each of the
leads in P7 and a good clean chassis ground
connection. Be very careful that the connec-
tion pins in P7 are not damaged or spread
out.
6. The resistance should be very high. A read-
ing of 500,000 (500k) ohms or higher is
acceptable.
7. If the resistance is lower than 500k Ohms,
replace the potentiometer and mode switch
plugand lead assembly, or replace the defec-
tive component within the assembly. See
wiring diagram.
8. Perform the resistance tests per Table F.3.
9. Ifthe resistance readings are not as specified
in the table, replace the potentiometer and
mode switch plug and lead assembly, or
replace the defective component. See the
wiring diagram.
10. If testing is complete, plug P7 back into the
control PC board and perform the Case
Cover Replacement procedure.