Lincoln Electric RANGER 250 SVM150-A Service Manual page 92

F-42
DIODE
MODULE
TERMINALS
Check Diode Module
10. Using the analog ohmmeter, connect the
negative meter probe to the terminal on the
diode module. See Figure F.19. Connect the
positive meter probe to the heat sink. The
resistance should be very high (over 20,000
ohms).
11. Using the analog ohmmeter, connect the
positive meter probe to the terminal on the
diode module. Connect the negative meter
probe to the heat sink. The resistance should
be lower (approximately 300 ohms). Also
check diode D4 for shorted or open condition.
See the Wiring Diagram.
TROUBLESHOOTING & REPAIR
POWER MODULE TEST (continued)
FIGURE F.19 – DIODE MODULE TEST
RANGER 250
When all tests are complete:
1. Reconnect all leads previously removed.
2. Torque the capacitor nuts to 50-60 inch-
pounds.
3. If finished testing, perform the Case Cover
Replacement procedure.
F-42
HEAT SINK