"Pulsing" voltage, RPM drop with load.
This is a crude schematic of your charging system.
It doesn't show the steering column connector, and your '72 B-body may have a second fusible link and other differences.
Everything connected to the battery positive and the alternator output (black wire) should be the same voltage under any given condition.
Voltage only drops if current is flowing through resistance. For example voltage on the coil side of the ballast resistor will be lower when the ignition is on.
IF the amp power feed is attached to the battery or starter relay and the amp is cranked up, the ammeter will show power flowing to it when the engine is running. The amp has to be turned off to see if current is flowing to the battery or not. (ie to see if its getting charged by the alternator)
This is a crude schematic of your charging system.
It doesn't show the steering column connector, and your '72 B-body may have a second fusible link and other differences.
Everything connected to the battery positive and the alternator output (black wire) should be the same voltage under any given condition.
Voltage only drops if current is flowing through resistance. For example voltage on the coil side of the ballast resistor will be lower when the ignition is on.
IF the amp power feed is attached to the battery or starter relay and the amp is cranked up, the ammeter will show power flowing to it when the engine is running. The amp has to be turned off to see if current is flowing to the battery or not. (ie to see if its getting charged by the alternator)
