Cummins/Onan 1750DQKB — Testing the PMG
Testing & diagnosis · permanent magnet generator (PMG)
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
- HIGH VOLTAGE. Touching uninsulated high voltage parts inside the control and power output boxes will result in severe personal injury or death.
Procedure
- Disconnect connector 10 from the regulator output module.
- Start the engine at the set and let the speed stabilize.
- Measure voltage across lead pairs 10-1 & 10-4, 10-4 & 10-5, and 10-5 & 10-1 (at least 150 VAC for 50 Hz, 180 VAC for 60 Hz).
- If voltages are low or uneven, check all leads and connections and repair as necessary.
- Stop the set and measure resistance across lead pairs 10-1 & 10-4, 10-4 & 10-5, and 10-5 & 10-1 with a Wheatstone bridge per frame size.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- At least 150 VAC for 50 Hz sets; at least 180 VAC for 60 Hz sets
- PMG stator resistance: Frame 7 = 1.1, Frame 8 = 2.6
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.