My alternator wire melted.

Also check and clean all of the electrical connectors at the firewall and the connections to all of the accessories on your car. It will take some time but you will be surprised at what you will find after 40 + years., Use plenty of Dielectric grease on all of the connections after you have cleaned them. Poor grounds and loose electrical connections were a major problem in the 60's and 70"s.
Charging System Upgrade with a Tuff Stuff Alternator - Hot Rod Network