Testing generator Field coils

ctvpa

ctvpa

Senior Member
I have tested and evaluated every piece of my generator. It was professionally rebuilt.
I have had my local shop test it, the armature has been on the growler, all the wiring is correct. They tell me they have no idea why it is failing. Output at high idle is 2 volts.
Is there any way to test the field coils? Or just try changing them, or should I just drop the $200 for another generator. This one is in beautiful shape, no pits, and has never worked. Issue is I bought it during the restoration so I cannot return it. Everything is new.
I have polarized it, it will motor (not earth shattering fast but it worked).

Thanks to all of you that have helped on this quest.
 
Look up Tom Wesenberg, he is the generator specialist, I have sent him two and just preparing another for him to test, clean up and install his EVR unit
 
I have polarized it, it will motor (not earth shattering fast but it worked).
Click to expand...

This typical. Spin at maybe 30 rpm about right?

If it will motor then it should generate. You checked your wiring against the wiring diagram (which while simplistic - does indicate the generator internal wiring correctly.)

See http://www.webjunk.com/modela/wp-content/uploads/2008/02/wiring-diagramcolor2sm.jpg

Otherwise it might be a cutout issue. Or a "connectivity" (open circuit) issue.

Tom's the man though. He may have some quick and dirty checks off the top of his head that I would think about and go "oh yeah you can do that..."

Joe K
 
i sent mine to tom also, it came back a work of art date stamped and evr.
a rebilt unit may not have as good as a case as yours and be full of pits
 
The common long generator should draw about 4 amps on a 6 volt battery charger. Be sure to lift the adjustable brush off the commutator when you do this test, or slip a piece of paper between the brush and commutator.

Any chance the field windings were replaced, but installed on the wrong sides?
Does it motor in the same direction that the engine normally spins it, when you polarize it?

Be sure the field wire is connect to the adjustable brush. I've repaired a few generators that shops had the field and output wires on the wrong brushes.
 
Tom, How do I know if the field coils are on the wrong side? When I motor it does go in the correct rotation that to would spin on the car.
I will open it again and check the wiring.
When I first opened the generator, there was a thick yellow wax type substance, does this mean anything?
If you repair them, if I am still having problems can I sent it to you for evaluation?
 
If it motors correctly then the coils must be installed right.
Does the generator have a good ground at the mounting bolt?
Have you tested voltage at the output stud and generator case?
 
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