Cummins/Onan G1250s / M-1902s — Voltage Adjustment Procedure
Adjustments · Voltage regulator board
For the Cummins/Onan G1250s / M-1902s, from the Cummins/Onan service manual.
Applies to: Cummins/Onan HDKA, Kubota V1305-B engine
Before you start
- Do not change the 50/60 Hz setting on the regulator.
- The V/Hz Break Point pot is factory set and sealed; do not adjust.
Procedure
- Attach a voltmeter securely to the L1 and L2 leads.
- Start the generator set and place a typical load on its output.
- Use a flat-blade screwdriver to set the voltage adjust potentiometer for correct voltage.
- Retighten the locking nut when complete.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Ideal setting 117 VAC measured at L1-L2 terminals
- Voltage adjustment pot is a 10-turn potentiometer
Full service-parts list: Cummins/Onan HDKA →, Kubota V1305-B engine →
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.