MTFCA Forum

Steve is on his way back to Kansas, no side trips this time. Having maybe some trouble with his Regan type magneto charging system using 1156 bulb. Normally when engine is shut down bulb turns off. This time the bulb remains on at shut down. He has unplugged the bulb so nothing runs down.
Question: What’s going on here ??
Steve is currently in Springfield Ill Walmart parking lot.
Recombinations wanted. I’m in touch with him by phone.

If the diode fails shorted then the diode acts like a short circuit in both directions. My guess it failed?

I agree with Alden.
Diodes normally fail closed. So the battery is back feeding through the bulb and diode through the mag coils to ground.

Thanks just relayed to Steve. He’ll leave the bulb out for now. He’s checking other wires too his engine isn’t running as smooth as he thinks it should.

Running two diodes in series would protect against failure in either one. I don't know if the bulb would pass enough current to de- magnetize the magneto.

If the diode is shorted, the magneto will alternately charge and discharge the battery, so it would be better to disconnect it and charge the battery before he starts out and each day until he gets home. Do not drive with lights on and crank start if possible to extend the battery charge life.
Norm

I believe the bulb will also stay lit if the battery is hooked up backwards.

If need be I can get to him, 3 hr drive not problem. But what to bring?