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Alternator and Ammeter

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Active Member
Apr 15, 2010
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I have had an intermittent problem for a while but now it has become persistent and more intense.
It started as temporary full-scale oscillations of the ammeter just after starting that would die down after a few minutes. Then the duration of the oscillations increased and it took longer to disappear. I and my mechanic made some changes and did some diagnoses. We replaced the last of the aluminum wire with copper and substituted the diode and the voltage regulator with no real improvement. (Switched them back again.) Now, yesterday, I'm getting an audible (but low volume) high pitched squeal in my headset synched to the oscillations. (I'm guessing 5-7 Hz.) Turning off the alternator field switch made both the oscillations and the squeal disappear. Also, of course, the charging current!
So, what used to be annoying and puzzling is now a bit worrying.
Any suggestions?

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