Thermostat Test Procedure - Lincoln Electric Fleet 650 Service Manual

LINCOLN ELECTRIC

THERMOSTAT 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 determine if either of the Chopper Module Board Thermostats are functioning properly.
MATERIALS NEEDED
Volt/Ohmmeter
Wiring Diagram
TEST PROCEDURE
1. Turn off the engine on the Fleet 650 machine.
2. Perform the Case Cover Removal Procedure.
3. Perform the Chopper Module Capacitor Discharge Procedure.
4. Locate the thermostat on each chopper module board. See Figure F.28. See Wiring Diagram.
5. Label and disconnect plug J3 from the weld control board. See Figure F.29. See Wiring Diagram.
6. Using a volt/ohmmeter, measure the resistance from plug J3 pin 1 to plug J3 pin 5. The resistance
should be very low (less than one ohm). See Figure F.30. See Wiring Diagram.
7. If the resistance is high (greater the two or three ohms), one or both thermostats are open and
need to be tested individually.
8. Label and disconnect leads from the thermostat terminals. See Wiring Diagram.
9. Using a volt/ohmmeter, measure the resistance from one thermostat terminal to the other. The
resistance should be very low (less than one ohm). See Wiring Diagram.
10. If the resistance is high (greater the two or three ohms), the thermostat may be faulty.
11. If faulty, perform the Thermostat Removal And Replacement Procedure.
12. Connect any previously disconnected leads to the thermostat terminals and connect plug J3 to the
weld control board. See Wiring Diagram.
13. Perform the Case Cover Replacement Procedure.
Fleet™ 650 Service Manual
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