A coup'la questions & comments:

1. Why would you disconnect the battery to replace the alternator?

2. One presumes certain basic troubleshooting procedures prior to throwing
parts at the problem, like back all heavy nuts grounding the alternator,
squirt in a little magic juice, and retighten.

3. You are correct. Most general aviation shops don't have the
sophisticated tools to diagnose problems with alternators and regulators. A
fairly large shop dedicated to nothing but alternators, regulators, and the
like will. Most of these are in the automotive trade.

4. If the whine is coming mostly from the right front seat of the airplane,
you might want to think about how long it has been since you took her to
dinner {;-)

Jim



I had a whine last fall. Advice here was that it was not an open diode. I
convinced myself that it was. Swapped out the alternator with a rebuilt
and the problem went away. Of course, in the process, they disconnected
the battery and all the connections to the alternator. I never will know
for sure.