Folks:

It is very easy to test the generator on the plane.  The test is difinitive.

Disconnect the ground from the battery.  Remove all the wires from the generator.  Connect a volt meter between the armature of the generator and the generator case (ground).  Connect a jumper wire from the field terminal to the generator case. Start the engine. 

Voltage should track RPMs and reach 13-14 volts by the time you get to about 1500 RPM (probably sooner).

If this test fails connect the volt meter from the field terminal to ground and repeat.

If you get a volt or two, the generator is bad. If you get nothing flash the field then repeat the first test.

John Cooper
Skyport Services
www.skyportservices.net

See also the October 2008 issue of Coupe Capers for an article on the care and maintenance of regulators.