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Home›Repair guides›1. | Does adjustment of R21 “voltage adjust knob” on the

Cummins/Onan — 1. | Does adjustment of R21 “voltage adjust knob” on the

For these Cummins/Onan models: 300.0 DFT, 350.0 DFU, 350.0 WF, 400.0 DFV, 400.0 WK, 450.0 DFW, 500.0 DFY, 600.0 DWV, YB series.

Applies to: Cummins Onan 300 0 Dft, Cummins Onan 350 0 Dfu, Cummins Onan 350 0 Wf, Cummins Onan 400 0 Dfv, Cummins Onan 400 0 Wk, Cummins Onan 450 0 Dfw, Cummins Onan 500 0 Dfy, Cummins Onan 600 0 Dwv, Cummins Onan Yb Series

Procedure

  1. 4. | Are the reference voltage transformer (T21) windings and connections OK? 5 —_
  2. 5. Replace voltage regulator VR21. — —
  3. 6. | Does AC output build up to rated value before tripping CB21? 7 _—
  4. 7. | Are the rotating diodes CR1 through CR6 on the exciter rotor OK? 8 — C
  5. 8. | Is the exciter stator winding OK? 9 — E
  6. 9. Is the generator main field winding OK? 10 _ H
  7. 10. | Is the exciter rotor winding OK? _ _— F ITEM | |. CONDITION: UNBALANCED GENERATOR OUTPUT VOLTAGE YES NO METHOD |

Source: manual:900-0192 Onan UV 300-600 KW Generators & Controls Service Manual (01-1975).pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.