Possible bad alternator???

I took my car out yesterday, drove fine to the store........ Came back out and went to start it, cranked slowly, and noticed to ammeter was reading -40 amps!!!! I shut it off, and started to see a small wisp of smoke coming from the alternator..... the wire coming from the alternator to the firewall was hot, as was the wire from the bulkhead to the starter relay..... I disconnected the negative on the battery (just happened to have a crescent wrench), and waited a little bit....... I connected the cable back up, car started right up and ammeter worked normally....... got halfway home (I only live about a mile away), and the ammeter went back to -40 amps....... I did the MAD ammeter bypass this morning, but it didn't change anything (kept getting some arcing while connecting the battery)..... Kept disconnecting things off the alternator, until I disconnected power from the alternator, that's when the arcing stopped..... Alternator shorted internally???? Possible bad connection at the bulkhead connector???