I suppose the first question to ask is "which fuse blew?" The next question I would ask is did you turn off the 12v
rectifier and check the 120v stuff first? Do you literally mean a 12v
fuse, or a 120v circuit breaker?
I think that is what I would do first. Turn off the 12v
charger (or disconnect it). The check each 120v outlet and appliance.
Then turn of the 12v charger and see if it is outputting 12v. Next, turn on the 12v items one at a time until you find soemthing that doesn't work.
Maybe that will help a bit.