Control Potentiometer And Mode Switch Resistance Test Procedure - Lincoln Electric RANGER 305G EFI Service Manual

LINCOLN ELECTRIC

CONTROL POTENTIOMETER AND MODE SWITCH RESISTANCE TEST PROCEDURE

Service and repair should be performed by only Lincoln Electric factory trained personnel. Unauthorized
repairs performed on this equipment may result in danger to the technician or machine operator and will
invalidate your factory warranty. For your safety and to avoid electrical shock, please observe all safety
notes and precautions detailed throughout this manual. If for any reason you do not understand the test
procedures or are unable to perform the test/repairs safely, contact the Lincoln Electric Service Department
for electrical troubleshooting assistance before you proceed. Call 1-888-935-3877.
TEST DESCRIPTION
This test will check the Output Control Potentiometer, Arc Control Potentiometer, Mode Switch and
associated wiring for damage, proper operation, tracking and grounds.
MATERIALS NEEDED
Volt/Ohmmeter
Wiring Diagram
TEST PROCEDURE
1. Turn off the engine on the Ranger 305G EFI machine.
2. Perform the Case Cover Removal Procedure.
3. Perform the Capacitor Discharge Procedure.
4. Label and disconnect plug J7 from the weld control board and visually check the plug and attached
wiring for damage, corrosion, improperly seated or damaged contact pins. Plug J7 will remain
unplugged for the following test. See Figure F.19. See Wiring Diagram.
5. Set the mode switch into the "CC-Stick" position.
6. Using a volt/ohmmeter, measure the resistance between each of the leads in plug J7 and a good
clean chassis ground connection. Be very careful that the connection pins in J7 are not damaged or
spread out. The resistance should be very high. A reading of 500,000 (500k) ohms or higher is
acceptable.
7. If the resistance is lower than 500k Ohms, replace the potentiometer, mode switch plug and lead
assembly or replace the defective component within the assembly. See Wiring Diagram.
8. Perform the resistance tests outlined in Table F.3. See Figures F.19 and F.20. See Wiring Diagram.
9. If the resistance readings are not as specified in Table F.3, replace the potentiometer, mode switch
plug and lead assembly or replace the defective component. See Wiring Diagram.
10. If testing is complete, connect plug J7 to the weld control board. See Wiring Diagram.
11. Perform the Case Cover Replacement Procedure.
Ranger® 305G EFI Service Manual
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