Help! Lost electrical power - NO LIGHTS!
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  1. #1
    Senior Member the-wild-man's Avatar
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    Sep 2010
    Columbia County, PA
    After realizing that none of my lights were working, I found that I had a direct short to ground. I did NOT have a battery in the bike at the time. In trying to find out what the problem was, I disconnected the DC wire from the regulator and there was only measuring 0.68 volts at the terminal, with the engine revved up. When I connected a spare regulator that I had, I got exactly the same result. With no regulator connected, I get about 35 volts AC across each leg (delta configuration) of the magneto. But when the regulator is connected, the AC voltage drops down to 1.1 volts, with the DC (positive) terminal not connected to anything. The spare reg does the same thing.

    With the digital meter set on diode check, and the red (+) lead on the regulator's ground, I get a reading of between 575 and 600 to each of the regulator's 3 AC input terminals, and between 1150 and 1200 to the positive DC output terminal. Both regulators gave similar readings.

    Do I have 2 blown regulators, or a fried magneto?

  2. #2
    Senior Member FortPayne's Avatar
    Join Date
    Nov 2011
    If your bike is running and putting out juice, I would say regulator. If the magneto was dead so would be your bike.
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  3. #3
    Senior Member the-wild-man's Avatar
    Join Date
    Sep 2010
    Columbia County, PA
    The magneto has separate coils for the ignition and the 12 volt electrical system. The 12 volt magneto coils are set up in a triple phase delta configuration, I think. The rectifier/regulator converts it to 12-14 volts DC. I had the battery out because it isn't good. The lights did flicker a bit, but they did work, when the engine was running. But after discovering and removing the short, the lights would not work any more. After swapping in a different regulator, the lights are still dead.

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  5. #4
    Banned qwerty's Avatar
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    Jul 2010
    NW Tennessee

  6. #5
    Senior Member heyduke's Avatar
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    Aug 2010
    My first thought would be the obvious....put a good battery in and see what happens.

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