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-   -   weird electrical problems (http://www.airforums.com/forums/f37/weird-electrical-problems-18572.html)

Chuck 10-03-2005 02:27 PM

weird electrical problems
 
so I installed a "new" automotive stereo in the camper a few weeks back. ("new"= "hand-me-down", but way newer than 1973. probably a '93 model, all-electronic, etc, etc). Just noticed some odd behavior. While listening to the radio, if I turn on the galley light, the sound cuts out compltetely. The stereo stays on; just no sound. shut off the galley light...sound returns. same thing with one of the overhead lights, although, I think one of them actually did shut the stereo off entirely.

at first, I thought it might be because the battery was disconnected, as I've read that it acts like a "buffer", of sorts. but plugging in the battery doesn't change anything.

also noticed on the last outing....had TV on, (current model...2 years old, ac/dc CRT), connected to shore power, 30 amp, no extension... when the furnace blower kicked on, TV got all wonky. (looked like scrambled cable). It didn't return to normal after the blower shut down. Tried "re-booting" to de-gauss the tube, but that didn't seem to work, either. So I unplugged it from 110, and plugged it into 12v recepticle. Picture came back (weak signal during this whole test...possibly related?), but now the univolt "hummm..." was coming through to the sound, and a solid line passing through the pic. never seen this before.

Univolt seems to be working properly. At last test, it was putting out a steady 13.5v. I can't think of what may have changed on the system that would be causing these oddities. only thing that comes to mind is that I did have the furnace out a couple of weeks ago to replace the thermocouple. so it got disconnected/re-connected to power.

Didn't think to check the TV over the weekend, whilst plugged into "known good" power at home. But the radio acted up. (had the ball game on while puttering outside....GO SOX!!!)

azflycaster 10-03-2005 03:38 PM

The heater / TV problem sounds like a fan is bad and putting out electical noise. The problem with the radio and the sound cutting out might be resolved with a string of garlic.

overlander63 10-03-2005 04:00 PM

How about...
 
You have a speaker wire output hooked up to a 12v power line at the radio? It may also explain the odd behavior of the TV set. You are feeding back power into the radio, causing it to become a transmitter, and it is jamming the TV signal. Try unhooking the radio, and see if the TV starts working again. If that doesn't do it, I can refer you to a good exorcist...:devil:

Chuck 10-03-2005 04:39 PM

Quote:

Originally Posted by overlander63
You have a speaker wire output hooked up to a 12v power line at the radio? It may also explain the odd behavior of the TV set. You are feeding back power into the radio, causing it to become a transmitter, and it is jamming the TV signal. Try unhooking the radio, and see if the TV starts working again. If that doesn't do it, I can refer you to a good exorcist...:devil:

that would be difficult to achieve. power supply isn't anywhere near the speaker wire bundles, and each speaker line has a factory installed plug-like connector.

also, these symptoms were occuring independantly...when the tv was acting up, the radio was not on, and when the radio was acting up, the tv was not on.

overlander63 10-03-2005 04:42 PM

So, was any of this happening before the "newsed" radio install?

Chuck 10-03-2005 04:58 PM

Quote:

Originally Posted by overlander63
So, was any of this happening before the "newsed" radio install?

no. the old radio wasn't original, but it was "older". had a cassette player, but an analog tuner.

the TV has been sensitive to low voltage, or sudden drops in voltage, when running on 12v. but on 110, has never shown any trouble at all. I suspect that modern stuff...even stuff meant for 12v systems, needs to be in a much narrower range than older stuff would tolerate. but that doesn't explain the radio's behavior. it cut out even when plugged into shore power. even though its always "12v", the voltage should be steady when coming through the converter, yes? (maybe no...).

probably a bad ground. odd symptoms almost always mean "bad ground", don't they? :lol:

overlander63 10-03-2005 06:30 PM

Quote:

Originally Posted by chuck
no. the old radio wasn't original, but it was "older". had a cassette player, but an analog tuner.

the TV has been sensitive to low voltage, or sudden drops in voltage, when running on 12v. but on 110, has never shown any trouble at all. I suspect that modern stuff...even stuff meant for 12v systems, needs to be in a much narrower range than older stuff would tolerate. but that doesn't explain the radio's behavior. it cut out even when plugged into shore power. even though its always "12v", the voltage should be steady when coming through the converter, yes? (maybe no...).

probably a bad ground. odd symptoms almost always mean "bad ground", don't they? :lol:

My experience has been that when you do something, and you immediately have a problem, chances are good it was at least in part something you did or did not do when you did what you did.
Umm, that doesn't look right, but I don't know how to fix it...:huh:
Anyway, it is probably something to do with the newsed radio, or the install.

72 tradewind 10-03-2005 09:44 PM

weird electrical
 
I wired a cd/radio from a late model vehicle and the audio went bad the first time I used it when plugged into shore power. The ac ripple from the univolt apparently screwed with the radio. The battery is a filter for the ac ripple but I did not wire directly into the battery. If I try another radio I will run a wire straight from the battery. Just food for thought.

smily 10-04-2005 07:03 AM

Quote:

Originally Posted by 72 tradewind
I wired a cd/radio from a late model vehicle and the audio went bad the first time I used it when plugged into shore power.

Me too. Brand new CD player bit the dust

Tom Nugler 10-04-2005 01:05 PM

Grounds, Voltage Drops and High Resistance
 
Most of these difficulties sound a lot like voltage drop and poor body grounds.
I don't know when Airstream stopped using aluminum wiring but I can tell you that my GT has had It's share of hot outlets and even arcing at connections in both the outlets and by the battery. The aluminum wire had developed corrosion causing resistance, causing heat, loosening terminals, causing more resistance, ect, ect.
Even with copper wiring there are still body grounds, (more aluminum), to cause voltage drops and the resulting lackluster performance of lights, fans and all of our creature comfort items.
I've replaced the breaker box, breakers and cleaned and tightened wiring in the battery compartment and replaced some outlets with some success maybe this could be of help to you as well.
Good luck, Tom.

Jim & Susan 10-04-2005 01:48 PM

Quote:

Originally Posted by Tom Nugler
Most of these difficulties sound a lot like voltage drop and poor body grounds.
I don't know when Airstream stopped using aluminum wiring but I can tell you that my GT has had It's share of hot outlets and even arcing at connections in both the outlets and by the battery. The aluminum wire had developed corrosion causing resistance, causing heat, loosening terminals, causing more resistance, ect, ect.....

Good luck, Tom.

I don't know the year either, but my '73 Overlander has copper wire. A good muti-meter may be the answer for Chuck's '73. It really sounds to me like a bad ground or voltage in the wrong place either on the "newsed" radio or even worse, the heater.

Good Luck, Jim

edmatlock 10-04-2005 03:18 PM

Radio quits
 
The radio you have requires a non-grounded speaker. If you are using the original Airstream installed speakers, one wire is maybe grounded to the trailer. You can't rewire all the speakers because the wire is in the wall. You can go to radio shack and get a 8 ohm to 8 ohm transformer for each channel and that may fix it.


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