Cummins/Onan 1750DQKB — Testing Diodes (Rotating Rectifier Assembly)
Testing & diagnosis · exciter rectifier bridge
For the Cummins/Onan 1750DQKB, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 1750DQKB, Cummins/Onan DQKB, Cummins/Onan DQKC
Before you start
- Layers of dust can cause diodes to overheat and fail. Brush dust off regularly.
Procedure
- Disconnect the diode pigtails from the terminal posts.
- Using an ohmmeter, measure resistance between each diode pigtail and the plate on which it is mounted.
- Reverse meter test probes and repeat; resistance should be high in one direction and low in the other.
- If resistance is high or low in both directions, replace the diode.
Tools required
- Ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan 1750DQKB →, Cummins/Onan DQKB →, Cummins/Onan DQKC →
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.