We had the problem of bouncing loadmeter needle in our 74 Archer. It came
and went, but it bothered everyone because no one could guarantee that it
wasn't a sign of impending trouble, even though a lot of people told us that
many, many Cherokees have that problem. We found a lot of potential fixes
in various places on the internet. One of the recommendations was to change
the regulator for a solid state one. One of our partners said this was too
much and that we should clean all the contacts before we invest in a new
regulator. So he and another partner spent most of a Saturday cleaning all
the contacts, including some in the alternator. When they put it back
together, there was no charging at all. Then they discovered that the extra
washer they had when they were done was an insulating one, and that they had
shorted the field winding to ground. This had fried the (solid state)
regulator, so nothing worked even after putting the washer back where it
belonged. So finally, they turned it over to the A&P who reassembled the
alternator, replaced the regulator (with a solid state one, again), and
checked everything out. Everything now works perfectly. No needle bounce,
rock solid. Unfortunately, we will never know if the problem was the
regulator, a loose connection, or dirty contacts. We're also a few hundred
$$'s poorer.

--
Bob (Chief Pilot, White Knuckle Airways)

I don't have to like Bush and Cheney (Or Kerry, for that matter) to love
America

"Bob Noel" wrote in message
...
In article ,
(Leo) wrote:

Usually the hand on my ammeter bounces for a few moments while taxing
and then settles down at about 20 amps. Yesterday it continued to be
erratic with a few calm moments with the hand indicating 10 amps. The
ammeter has 1976 stamped on the back. Do these things ever wear out?
Is there any way to bench test one? I need a few opinions, what is
the most likly culprit - ammeter, regulator or alternator? Thanks Leo

from the Cherokee hints & tips, there are several potential causes.
Most are related to loose connections or corroded connections (the
connection heats up, becomes open, cools off and closes). The time
I had a bouncing ammeter, it was caused by a bad master switch.

Checking and cleaning all the connections is the cheapest first step
in troubleshooting this (assuming you are doing it) rather than trying
to isolate the problem by swapping out the ammeter, regulator, or
alternator.

--
Bob Noel