Generator Output

[Ron P.]

Recently rebuilt my generator for my 31 coupe. It appears i'm not getting any output from the generator. I moved the third brush up and down with no change in output. The amp meter looks good, when i turn the lights on it discharges. But with the engine running i get no charging on the amp meter.
What could be my problem, wiring or a short?
Ron

 

[Charlie Stephens]

Have you done anything else recently, like change the wiring?

Charlie Stephens

 

[4port]

Try polarizing the generator. Momentarily connect a jumper wire between the the two posts on the either side of the cutout. An 8" wire with bare ends can be held by hand against one post and touched on the other.

 

[redmodelt]

Was it working before? Did you have the armature checked?

 

[4port]

Another simple bench test is to see if the generator will " motor", run like an electric motor connecting a set of battery cables from a battery to ground on the generator case and the output terminal post. If it won't motor it won't put out charge current.

 

[Ron P.]

Did all the above but still no output. New Armature and coils. Does one wire from the coils go to ground?

 

[Purdy Swoft]

One of the field coil wires usually grounds under the output terminal or in some cases under a ground screw . the other field coil wire connects to the third brush . If the field coil wires get reversed the generator will still charge , usually at maximum rate . Moving the third brush up or down will have no effect on charge rate if the field coil wires are reversed ... If the wires are reversed it will damage the field coils very quickly . Sometimes when polishing up the commutator The brass will will transfer and ground out the commutator. I always use a hacksaw blade to under cut the gaps on the commutator . If you tested to see if the generator would motor and accidently touched the ground wire to the out put post , you will need to repolarize the generator or it won't charge .

 

[Patrick L.]

You really didn't answer that question, did it motor ?

Regardless, Purdy gave the info.

 

[Mike V. Florida]

I don't see cutout mentioned. Are you testing it in the car? Have you tried to bypass the cutout?

 

[Tom Wesenberg]

Polarize it, then try it.
If no charge at fast idle, then jump across the cutout with a wire while the engine is at fast idle.
Still no charge, then polarize it with the fan belt removed, and if it spins opposite of the normal rotation, the field coils need to be swapped side for side.