Cummins/Onan — Generator Voltage Adjust (R21)

Adjustments · Voltage adjust control R21

From a Cummins/Onan service manual — check it applies to your exact model before use.

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Procedure

1. Start generator set.
2. Prepare installation equipment for Test Without Load.
3. Operate Phase Selector switch to read generator output current and voltage.
4. Insert a screwdriver into the Voltage Adjust control on the front of the generator set control and carefully loosen the locking nut.
5. Slowly turn the screwdriver clockwise to increase voltage, or counterclockwise to decrease voltage.
6. When set at correct voltage, tighten the locking nut. Be careful not to change adjustment.
7. If correct voltage cannot be attained by R21 adjustment, refer to VRAS-2 adjustment procedure (K).
8. Observe that ammeter does not register any output current. If output current is observed on the ammeter, contact an Onan representative.
9. Move the Phase Selector switch to the Off position.
10. Stop generator set, and prepare all installation and generator set controls for operation readiness.

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.

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