My 1996 Starcraft has a 6620 Magnetek converter. I have checked and triple checked the battery. It doesn’t seem to be the problem. The electrical worked inside the trailer last season but I cannot get it to work when on DC this year. All lights work when hooked up to AC. The manual isn’t much help since it’s says the converter has a 3-position switch to change power source but the only things I see when I open the cover to the converter are 2 - 20 amp breakers and 4 - 15 fuses. I’ve checked all the fuses and they’re in good condition. I just tried the voltmeter on the battery again and it’s where it needs to be. Any hints on where else to look to problem solve the issue?