12-01-2011 Ask Mike! Archive
I'm getting some whine in my headset.

Hey Mike,

I'm getting some whine in my headset.  I've heard to suspect a bad diode in the alternator (actually the rectifier, which is part of the alternator).  Any tests I should do to confirm/disprove/narrow down?  Idea how long it would take to fix/how long the plane will be down?

Dave

Hi Dave;

Yes, a bad diode can cause this. Also, could be a grounding issue...somewhere.  In the mode of troubleshooting, make note of what the load was (what all is turned on), see if it gets better or worse with less load or any particular item on (strobes, nav lights, panel lighting, etc.)  Reduce the load down to minimum, then switch the alternator off, reinstate the load to confirm it has gone away or if it may still be present.  Reduce the load again to minimum before turning the alternator back on.  If you have any electrical items not working, this may be a clue, also.  (One time I found an electric oil pressure gauge connector that was causing enough 'noise' to drive an ADF nuts.)

If we need to send the alternator off, I get real good service from George's Electrical in Sacramento, typically a 2-day turn plus freight.

Let me know, we'll get you worked in.

Mike