Dynamo - Charge Light Faults

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Although not as useful as the charge light on 12v AC machines, a reasonable guide to faults can be obtained from the charge light on 6v DC bikes.

Light Fails to Extinguish at High RPM

• Regulator terminal D+ shorted to earth
• Wire 61 shorted to earth (red wire from regulator terminal 61 to ignition switch terminal 61)
• Field coil on dynamo shorted to earth
• Regulator defective

Ignition ON, Engine Stopped, Bulb Fails to Light

• Battery discharged
• Fuse blown or fuse box corroded/defective
• The wire from 30 (+ve fuse) to ignition switch broken
• The wire from 31 (-ve fuse) to battery broken
• The wire from D+ on dynamo to the regulator broken
• The wire 61 from regulator to ignition switch broken
• Bulb blown
• Bulb fitting corroded/defective
• Regulator cut out defective

When checking "broken" wires for continuity, also ensure that their respective terminals are clean and uncorroded.

As the charge light doubles as the indicator repeater it is useful to know the correct indications.

 

Charge Light/Indicator Repeater, Correct indications.

Ignition ON Engine STOPPED Indicators OFF	Charge Light ON
Ignition ON Engine STOPPED Indicators ON	Charge light flashes in phase with indicators
Engine RUNNING Indicators OFF Dynamo CHARGING	Charge Light OFF
Engine RUNNING Indicators ON Dynamo CHARGING	Charge light flashes out of phase with indicators
Engine RUNNING Indicators OFF Dynamo NOT Charging	Charge Light ON
Engine RUNNING Indicators ON Dynamo NOT Charging	Charge light flashes in phase with indicators

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