1978 31 Center Bath Sover.

[Mitch54]

Hi Guys,

Just got the 78 home which the lady that I spoke with said it was a 76. Well powered her up and her lights and everything were on for about 1 hour. Well I heard a slight sizzle in the front end and everything is black, flipped the breakers and nothing. The Air Conditioner still works but no of the lights or any thing else will work. checked the 120 breaker box and nothing was tripped, any suggestions?

[Bill M.]

All of the lights work on 12 volts from the converter. In fact everything except the AC works off the 12 volt system. Sounds like a short somewhere blew a 12 volt fuse. On our 88 model the converter is under the sofa in the front between the 2 battery compartments that open from outside. On ours you can access some of the dc fuse panel behind the sofa. You have to pull the sofa to get to the converter. It would be good to check the DC fuse panel first and hope that one is blown so that you can narrow down which circuit to work on. There is also a main DC cut off switch. Ours is a rotary switch behind the sofa. I suppose that it is possible for it to fail also. Sounds like a wiring problem instead of a converter problem since the lights should keep on working off the batteries. Does it have batteries in it? If not maybe a cable shorted in the battery box. I guess I would start by metering all of the DC circuits one at the time until I could isolate the circuit and then check it piece by piece.

[Mitch54]

there is no battery connected currenty, I am thinking it may be the converter but I am unsure. I checked the fuses and all appear good. I used the multimeter to test them. If its the converter how big of an issue would it be? Could an electrican fix it or would it require purchasing a new one?

[Mitch54]

Does the Univolt converter have its own fuse inside of the unit itself that could have blown? I found a field mouse nest on top of the unit when I pulled the cover off. Could that have caused it to short itself out or something to the nature? The Univolt is not humming or anything like it should either. Does it have to have a battery in the trailer to work properly? Just weird how it was working awesome, then a sizzling sound, then nothing.

[NavyCorpsman]

Hi I have a 78 rear bath Sovereign.
Anything with a light bulb in it is on a 12 volt circuit, supplied by the battery that is maintained by the converter. I use an Interstate Deep cycle battery. It provides plenty of reserve.
The 120VAC circuit supplies power to the standard outlets throughout the trailer and the outside weatherproof outlet. It also supplies the Microwave and Dometic refer.
Make sure of the following: Good battery with clean terminals, check the fuse block for bad/blown/open fuses, I periodically pull mine one by one and check for oxidation that can give a small voltage drop.
As with all things, the breakers are generally maintenance free, but if they are 36 years old, I would replace them. If you are handy you can do it yourself easily, or an electrician can replace them in about 15 minutes.
Hope this helps. Sounds like an easy fix. Let me know if you have additional questions.
Clayton

[NavyCorpsman]

Oh, BTW, your UNIVOLT is more than likely dead. It has three obsolete Mallory capacitors, and the 1N32 Diodes are more expensive than a new converter. I wanted to rebuild mine to keep it true to original.
The new convertors are smaller, lighter, run cooler and are quiet. A 35 amp 12v power convertor is around 100 dollars on Amazon. Many brands to choose from.
All will fit in the existing plastic holder.
Make sure ALL the bus bar (fuse block leads) are clean and snug. If the Univolt was fried, it will smell like it.

[rmkrum]

Nothing quite like the scent of fried electronics in the morning.....😄


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[Mitch54]

Ok guys, took out the old univolt and replaced it with the Intelipower 9160 60 Amp converter. I have all the wires hooked up but when I plug the trailer in to city power it kicks the breaker for the lights. I don't have the ground chassis on the unit attached to the ground lug on the intelipower unit but does that matter? The old univolt did wonderful until it died (most likely because of the rat nest on top and in it) is there anything that I should check, the fuses are all good in the 12 volt distribution panel, would the ground lug and ground chassis on the intelipower
cause it to kick the breaker in the trailer

[NavyCorpsman]

Old circuit breakers can trip with little provocation. Did you have the inverter connected to a load when you powered it up? You can test the condition of the 120V circuts by doing the following: DISCONNECT SHORE POWER. You may also trip the breakers as well. Using Volt-OHM meter, Test for AC Voltage. Then using the Ohm scale, check between the outlets common and neutral leads (the blade connectors. The all should read infinity. If there is any resistance readings, there is a short somewhere in that part of the circuit. Also check between the ground and the common/neutral sides. Again, anything other than infinity will locate a problem with the wiring. As for grounding, I would ground the unit. that should not affect its normal operation, bur in the event of a catastrophic failure id would provide a path to ground at the unit. On the issue of grounding, my AS has a #6 Copper wire bonded to the frame next to the street water lintake. Check that too.
The elephant in the room may be a wire that was accidentally drilled into for whatever reason. By schematic, my outlets are wired from the roof down to the receptacle. Check for holes or installations above the receptacle.
The problem is small....you just have to find it. Don't let it frustrate you too bad. You will win this one.