Marathon MagnaPLUS Series User Manual

MagnaPLUSGeneratorTroubleShootingGuide(SP0023).docx12/27/2018TRS 1 
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Trouble Shooting – MagnaPLUS / Mariner / Harsh Duty
MagnaPLUS / MARINER / Harsh Duty models are 12 lead, re-connectable, brushless, AVR regulated
generators. For simplicity, MagnaPLUS refers to all three product lines. A listing of models and
specifications is included at the end of this trouble shooting guide.
A MagnaPLUS generator is simple to trouble shoot with 6 main components: the exciter stator and
exciter rotor windings, a voltage regulator, a rectifier assembly, and the main stator and rotor
windings. For tools you will need a good multi-meter – a Fluke works very well – a ratchet set, and a
set of screwdrivers. You can make an analog style meter work as well.
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Figure1
This trouble shooting guide addresses the most common causes of low or no output voltage, usually
15V – 50V as measured at the generator terminals, mounted on the linkboard located in the connection
box mounted on top of the generator.
Start trouble shooting in the connection box mounted on the top of the generator. It gives easy access
to the exciter stator leads ( F+ & F- ) and main stator output leads.
If your generator is equipped with a PMG Excitation Support system refer to the section on PMG
Powered Regulators on page 6.

Marathon MagnaPLUS Series Specifications

General

Brand	Marathon
Model	MagnaPLUS Series
Category	Portable Generator
Language	English

Summary

MagnaPLUS Mariner Harsh Duty Troubleshooting Guide

Exciter Stator Continuity and Resistance Check

Tests exciter stator winding continuity and resistance for faults.

Constant Excitation Test Procedure

Performs a test with the gen-set running to check excitation performance.

Main Stator Winding Inspection

Measures main stator winding continuity and resistance for faults.

Diodes and Rectifier Assembly Testing

Tests diodes within the rectifier assembly for proper function.

Field Flashing and Residual Magnetism Restoration

Procedure to restore residual magnetism lost during prolonged inactivity.

PMG Powered Regulators

PMG Capacitor Testing

Tests the PMG system capacitor for correct capacitance and charge/discharge.

PMG Stator Continuity and Resistance Check

Verifies PMG stator winding continuity and resistance values.