I have recently posted on this same problem. My 66 lights and 12v
stuff went off when my wife tried to turn on one of the old ceiling lights. I think she turned the switch the wrong way, it shorted out.
I looked everywhere for a fuse- supposed to be 30amp. Have not yet found one.
I replaced the 8amp in the rear access panel, which looked suspicious, but nothing happened. The converter works, as I hear it hum. All shore power items on AC work too.
Yesterday it was recommended I look at the light itself as it may have an inline fuse in the ceiling somewhere near it. Have not yet done this.
I also took out the shelf in the bathroom closet above the converter grabbed the white wire to see where it went and that was of no help.
My owners manual is wrong-- it says the trailer has a screw in home tpe fuse, 40 amp somewhere. The diagram, is wrong too. Guess Airstream had a generic manual they gave with the trailer that was never updated back then.