Classic/Antique Car Repair: Generator warning light on, chevy passenger car, regulator setup

Question
I have a 1956 chevy passenger car with origional generator/regulator setup. I rebuilt the generator with a new armature and it worked fine for a few weeks, now the gen. warning light is on all the time. I disassembled it and checked the armature and field coils for shorts/open circuit, found nothing wrong. I replaced the brushes too. The only odd thing I noticed when this started happening was that    the aftermarket ammeter I had installed was pegged all the way to -60 amps, and stuck there, so I took it out of the circuit.

Answer
I'm guessing this happened when the engine was shut off - right?   If so, what happened was that the "cut out" contacts in the regulator stuck shut, so that the battery began discharging back through the generator.  Usually this burns up the generator pretty quickly, and may cause a fire in the wiring, especially the armature to voltage regulator wire.   This can happen because of an incorrect or just plain bad regulator, and the nasty thing is this may not happen again right away, so it is hard to track down.  Unless you have some other symptom, I'd just get a replacement voltage regulator.

If the generator won't charge now, and yet it checks out OK electrically, try grounding the field terminal to see if it starts charging - if it does, the finger points to the reguator also.

If the generator still won't charge, you'll have to take it apart again, and verify that the armature didn't get fried in the process - check for shorts, continuity, and thrown solder.

Of course it is remotely possible that it IS charging, but the Idiot light stays on for some reason.  If that's the case, check your wiring from the ignition switch to the light, and from the light to the regulator terminal it is supposed to be connected to (terminal #4).  

You probably know this, but to find out if it is charging, start the car, set it at fast idle, then pull off one battery cable.  If it stalls, it isn't charging.  If it continues to run, start turning on electrical loads.  If you can turn on the parking lights and radio without it stalling, it is charging pretty well.   Of course it has to be a fast idle to do this.

Good Luck!

Dick