Unless someone has added an inverter (12V DC to power 120V AC outlets) then it would not have one, don't think they came with them that far back. I know my 72 Champion, 76 Travco (Dad's) and 94 Alegro Pusher did not have them from the factory. You probably have a converter, which is like a battery charger, turning 120V Ac to 12V DC to charge the batteries. The converter is only in use when plugged into shore power. With that thinking, there will be an isolator that will allow the engine alternator to charge both the engine and house batteries, but make them drain sepatately as to not kill the starter battery with the lights and other 12v DC stuff in the coach. It is normally shaped like a brick and has multiple 1 gauge wires off it and usually a smaller trigger wire. Follow the positive from the battery and also from the alternator, in the middle somewhere, you should find it. Test voltage at back of alternator, then into isolator, then out of isolator, then to battery positive lead. Rerport back with the voltage readings. Make sure to have a hot battery to do this test.