[Corley]

What Kurt said. Easily fixable with no special tools. Sounds like your regulator went South, but could also be a diode issue, those you can check with a meter.

If using one with a sense line, (not a one wire version), and the sense line opens up for any reason, the output voltage can rise to a level that can destroy parts inside the alternator, but also anything electrical on the car. A regulator failure can cause the same problem.

On the other hand, (again if not a one wire version), if the excite line opens up, you will need to raise the rpms pretty high for it to start charging.

If the output line opens up, internal damage will most likely result in the form of a damaged regulator. You should not shut off a battery disconnect while the engine is running, as the voltage can "run away", depending on how it is connected.

All these things are easily fixable by anyone. Internal wiring doesn't seem to ever fail. Bearings get noisy, easily replaced. Brushes wear out, no big deal to replace. Hardest part of working on these is finding a paper clip to hold the brushes in place while reassembling the case.