Marathon — Frequency Selection (ME-SE500 Voltage Regulator)
Adjustments
From a Marathon service manual — check it applies to your exact model before use.
Procedure
- Initially set the U/Freq adjust fully counter-clockwise.
- Run the generator at the desired full-load speed.
- Turn the U/Freq adjust slowly clockwise until the U/Freq LED lights.
- Turn the U/Freq adjust slowly counter-clockwise until the LED just goes out.
- The underfrequency control is now correctly set.
Source: Marathon 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.