RV Repair: Onan has no AC output, automatic transfer switch, voltage tester

Question
I own a 1977 Monaco (Diplomat II) 25ft.motorhome Problem: No AC output from the onboard Onan BF 4Kw generator.it starts up and runs great,I checked it's fuses and the AC and DC brushes as advised in the owners manual they appear to be almost new,the house battery works fine,there are three breaker boxes and I've reset them each several times,(one in the box where the Onan lives,and one in the box where you hookup to shoreline power and the one inside the motorhome in a closet).Question,I read somewhere that something called a "Transfer Switch" failing can cause you to loose AC power from your generator,could this be my problem? if so where would it be located? and what would it look like? also did they even have such a thing as a "Transfer Switch" in the 70's.
Thank You.

Answer
Hi Arthur
I don't recall "DIP'S" having an ATS (automatic transfer switch) outside of the converter in those years. But the first thing to do is check for power at the Gen-set's breakers. If you have it there, then you go looking for an ATS.
There is a switching relay in the converter that doesn't always switch, but it also wouldn't switch on shore power then either.
Your local hardware store sells a nice A/C voltage tester thats inductive ...just hold it up to a wire or breaker and it will tell if its hot or not.


Thom