(John) wrote in message ...
Most of the 24 volt Cessna's have the over voltage relay built into
the regulator. The over voltage protection has two stages. The first
stage turns off the field pass transistor. If the voltage still goes
higher the second stage turns on a crowbar SCR that blows an internal
5A fuse in the regulator.


I think mine is separate, per my comparison with the docs at
www.zeftronics.com. ("Type B" system using R25101 or R25102, not sure
which yet).

BUT I have not been able to find the OVR yet I assume its up under
the panel somewhere, but in that rats nest I can't find it. Can
anyone tell me which side? or high/low? Mounted or just hanging?
There are a few barrel-like connectors hanging around in there that
look about the same size is what I imagine the OVR to be.

From what you describe the alternator has field voltage (21.6) so it
should be generating current. With power off the field should measure
15-25 ohms. Your brushes may be worn out.

The field resistance was 18 ohms. I didn't try moving the prop to see
if it varied though-- I'll try that.


I had a problem a few years back where new brushes would not last 50
hours. I finally found that all of the replacement brush springs
were too stiff. There is two ways to fix this. Get the springs out
of a "OLD" junkyard alternator or cut a 1/4 inch off of the new
stiffer springs. I have no idea why the spring stiffness changed but
it is noticeable and measurable.


Wow. We DID replace our alternator just last August at annual time,
and it has about 50-75 hours on it since then...

Thanks for your input!

Cheers,
John Clonts
Temple, Texas
N7NZ