I have a theory or three
1: Circuit breaker (inside coach)Feeding converter triped
2: Screw loose,,,(Same breaker,,Or the assoicated white wire)
3: Blown fuse/tripped breaker,,,Converter output
4: Converter = Toast
and on some rigs...Mine included... 5: Converter plug came out of socket
(One of my convereters (I have 2 in parallel) The ORIGINAL one...Is a plug in model..The other one is normally disabled.. But from time to time #5 happens... When that happens I turn on the aux converter... (I usually figure it out around 3 AM so I'm not going out to plug back in)