Cummins/Onan — Voltage and Voltage Stability Adjustments (AVR)
Adjustments · Voltage Regulator VR21
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan DGBB, Cummins/Onan DGBC, Cummins/Onan DGCA, Cummins/Onan DGCB, Cummins/Onan DGDA, Cummins/Onan DGDB, Cummins/Onan DGEA, Cummins/Onan DGFA, Cummins/Onan DGFB, Cummins/Onan 4B3.9 engine
Before you start
- High voltage - use dry wooden platform or rubber insulating mat, dry clothing, no jewelry, elbow length insulating gloves
Procedure
- Measure generator output voltage while running without load at nominal frequency.
- Lock the control panel voltage trimmer at its midpoint if it cannot provide enough adjustment.
- Turn the VOLTS pot fully counterclockwise and the STABILITY pot to its midpoint.
- If the red LED lights, refer to Jumper Reconnections and UFRO Adjustments.
- Turn the VOLTS pot clockwise until rated voltage is obtained.
- If voltage becomes unstable under large load, turn the STABILITY pot clockwise until stable.
- Check and readjust the VOLTS pot each time the STABILITY pot is readjusted.
Specs & values
- Output voltage trimmer adjusts plus or minus five percent of nominal voltage
Full service-parts list: Cummins/Onan DGBB →, Cummins/Onan DGBC →, Cummins/Onan DGCA →, Cummins/Onan DGCB →, Cummins/Onan DGDA →, Cummins/Onan DGDB →, Cummins/Onan DGEA →, Cummins/Onan DGFA →, Cummins/Onan DGFB →
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.