Need some Electrical HELP!!!!

[Plum 71 RT]

Board members, been out of the country for awhile good to see you are still here. I am needing help . Took the car out last week and noticed that the factory Alternator gauge was in the discharge side . I changed the regulator and it was no help. Pulled the alternator and found that one of the field brush holders was melted and the brush was missing ( only wire was left ). I replaced the brush and the holder, checked the field wires 12V at the Blue/White , Good ground on green wire to regulator and regulator ground good. Went to start car and gauge went to full discharge and new brush and holder went up in smoke. Does anyone have any ideas? Is armature or trio bad? Oh by the way I had Alternator tested by the local NAPA store , but if it is not a PHORD there lost.

[Mt.St.BigBlock]

Hi Plum71RT,
  Sorry to hear about your electrical problems. I'll take a stab at it here. I don't think
it has anything to do with the diode array as thats part of the stator side of the alternator.
There are a couple possiblities on the "other side". There is suppoed to be a insulated
washer as part of the mounting of the brush holder. If that is missing...disintergrated...etc
then the brush connector could get shorted to the case. I'm thinking though that would
maybe melt the brush holder but not the carbon brush itself. The other more likely possiblity
is that the rotor is shorted to ground. Normal field currect for a healthy alternator is about
2.5 to 3 amps according to the 71 factory service manual. Being that the rotor is probably
not repairable my call would be a new alternator. Good luck!! Jeff

[MEK-Dangerfield]

I have a nice chrome alternator I'll let you have cheap. I needed more power for an amplifier, so the standard 60 amp thing wasn't cutting it.

  Mike