Can you diagnose my univolt / power problem?

mwmoss · 07-22-2006, 09:18 PM

I have a 1974 25' Tradewind. I've been working on it this weekend at the house. This evening, I was preparing to repaint the bathroom countertops when I encountered a problem. I had the radio and several 12 volt lights on when I attempted to turn on the lights at the ceiling, turn-style switch. I clicked the switch a couple of times and what do you know... the entire 12 volt system went dead!

The 120 volt system seems to be fine (air conditioner and refrigerator run), I can't find any blown fuses, polarity light is not on, univolt still hums, deep cycle battery is 3 months old... what could it be?!

overlander63 · 07-22-2006, 09:57 PM

It could be corrosion on one or more of the fuses, try wiggling them a bit to see if the lights come back on. It could also be a corroded battery terminal or connector, or a blown ground fuse (blown ground fuse not likely, it is 50 amp)

AirstreamGypsy · 07-23-2006, 09:12 AM

Most likely all the 12v items are on a single circuit, like a daisy chain. You probably have a loose or disconnected wire on that chain. Check the wires coming in and going out from each light or 12v plug.

**wahoonc** · 07-23-2006, 09:23 AM

If it is the orginal light switch I would be willing to bet it just went south. I have one that is borderline and it gets hot, very hot eventually I am sure it will take a fuse with it when it goes. So check the switch with an ohm meter and your 12v fuses.

Aaron

68 Overlander · 07-23-2006, 12:42 PM

That sure sounds like a fuse or bad connection like Terry said because if the Univolt quit, your battery should have fed the lights, at least for awhile.
Did you check other DC accessories to see if they work? Water pump, furnace fan, etc. It could be that the lights and radio were wired to the same DC circuit.
Also, place a voltmeter on the output leads of the Univolt and the battery. If there is output from the converter, you can rule that out. If there is not, it could be that your battery has been powering your DC for some time and is now dead, although I would have expected some dimming of the lights first. What is the battery voltage?

mwmoss · 07-23-2006, 03:21 PM

Thank you all for your suggestions as they are very helpful!

I don't have a volt meter (maybe it's time to invest in one), so I started again with all the fuses. I finally figured out on the last fuse pulled that it had blown... it had seemed okay at the angle I was looking at.

Once the fuse was replaced, everything worked fine. I re-enacted the same scenario and blew the fuse again with the ceiling light. So, wahoonc was right in that the light switch has gone south.

Changing the subject a little, do you all still use the original univolt? Would it be wise to switch out for an Inteli-Power system, or just let things be until it finally gives?

Thanks again!
Matt

Buttercup · 07-23-2006, 03:43 PM

Quote:

Originally Posted by mwmoss

Thank you all for your suggestions as they are very helpful!

I don't have a volt meter (maybe it's time to invest in one), so I started again with all the fuses. I finally figured out on the last fuse pulled that it had blown... it had seemed okay at the angle I was looking at.

Once the fuse was replaced, everything worked fine. I re-enacted the same scenario and blew the fuse again with the ceiling light. So, wahoonc was right in that the light switch has gone south.

Changing the subject a little, do you all still use the original univolt? Would it be wise to switch out for an Inteli-Power system, or just let things be until it finally gives?

Thanks again!
Matt

Don't wait - switch it out. You will not regret it.

ArtStream · 07-23-2006, 04:15 PM

Quote:

Originally Posted by Buttercup

Don't wait - switch it out. You will not regret it.

I agree with Buttercup, just switch it out even if it is not at fault.
The intellapower type units manage battery charging much better then the old units.

Michael

26.982 amu · 07-23-2006, 06:08 PM

In addition to reliability and better battery charging, you will be mercifully free of the terrible HMMMMM noise the Univolt makes--especially at night.

harold owens · 07-23-2006, 08:02 PM

I had a problem with my univolt, it had no 12 vdc output. It turned out to be one of the 3 capacitors inside the unit. I replaced the bad capacitor and it worked fine

mwmoss · 07-23-2006, 08:09 PM

I am indebted to this forum... it's amazing the kind of resources you can find with the click of a mouse!

Okay, suppose I ordered an Inteli-Power system, would there be anything else I would need? Can the current fuse panel be used with the new system, or would you suggest changing it out? Anyone know of any step by step threads on installation.

Thanks, again!

Pacerized · 08-13-2006, 08:06 PM

I just bought my first airstream in late July (a 1981 excella 2). Our first trip in it was a nice outing to yellowstone, and everything worked great. Last night I was stocking it for a short trip this next weekend and still had no problems. This morning I seemed to have the same issue you are describing on this thread. I checked the breakers, had the battery load tested, and checked all the fuses although I didn't take each one out. When I use a volt tester I get power at the battery, and at the point where the battery cable runs from the 12v fuse panel to the univolt converter, but I get nothing from the white cable leaving the converter back to the fuse panel, nor at any other fuse. When I run a direct wire from the main fuse to any other fuse terminal then my lights work. Basicaly nothing works right now that involves dc, but anything that's strictly ac works fine. I can't even tow it to an rv center because the jack works on dc. I'm a little apprehensive in trying to work on the univolt, or taking the cover off.
Harold I noticed your post on the capacitor. How would I check to see if that's the problem, and where would I find the part?
Any advice would be greatly appreciated.
Thanks: Charlie

Calvin · 08-13-2006, 11:02 PM

Hi Charlie,
My trailer is probably different than yours, but the white lead is the negative (or common) lead for the dc power and is also connected to ground. The antique Univolt in my 1966 Overlander also had a fuse in it. The ac power wires were connected to it internally; and the dc power output was connected on external terminals. From there power went to the dc distribution/ fuse panel. As a thought, you could use a battery to operate the electric jack if needed.
Good luck,
Calvin

Pacerized · 08-15-2006, 08:13 PM

Quote:

Originally Posted by Calvin

Hi Charlie,
My trailer is probably different than yours, but the white lead is the negative (or common) lead for the dc power and is also connected to ground. The antique Univolt in my 1966 Overlander also had a fuse in it. The ac power wires were connected to it internally; and the dc power output was connected on external terminals. From there power went to the dc distribution/ fuse panel. As a thought, you could use a battery to operate the electric jack if needed.
Good luck,
Calvin

I think you're right about the white cable being the negative lead. I was planning on buying an inteli converter this Thursday at camping world, but first thought I would take apart my current converter. By the way I'm not certain that it's a univolt, but only assume it's the origanal converter. The lable on it says Triad-utrad model 735u TU-540-6. When I started taking the cover off all of my dc power came back. It turned out that I had a bad conection where the battery cable connected to my 12v fuse box. I took it off, and tightened it, and everything seems to be fine now. I think I'll stick with the current converter unless it starts overcharging my battery as I've read here. Thanks for all the advice.
Charlie