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foqus · 08-23-2009, 05:47 PM

Hello all,

I am still under warranty, so I will have this checked out in a week or two, but here's the problem.

My 2007 19' International has a Sony sound system installed, with four speakers and a subwoofer. The unit has always had a buzzing sound when turned on and no music/tv is playing. I did bring it to one repair place, but they said it was because my switch had been on "Store" while it was plugged in to power and that it had something to do with the battery. I took their word for it and drove off. But, just yesterday, with the loud humming going on while I was preparing to start up a DVD, I happened to walk over by the sink, near the bathroom, at the foot of the bed, and the humming changed and then will altogether stop if I place my feet in exactly the right spot. Oh, and the buzzing changes *pitch* if I turn on certain lights.

Any ideas, or do you think my AS is in for a MAJOR re-wiring?

thx

marco in San Antonio

SteveH · 08-23-2009, 06:23 PM

The converter can produce what is called ripple voltage on the 12 DC output that can/will produce the humming you are hearing. Now about it changing when you are in certain areas of the trailer, that's a new one on me.

TBRich · 08-23-2009, 06:34 PM

Try adjusting the subwoofer ... the subwoofer level knob is located on the subwoofer box under the curbside dinette seat. We have intermittent noises and sounds come of the speakers be we are usually able to "adjust it out" by adjusting volumes and subwoofer input.

We have found this to be more of a problem since we installed the Digital Converter Box on the TV which gives 3 remote clickers to deal with...the TV, the DVD/Radio and the Converter Box... it seems to happen if we have the volumes up high using two or more of the clickers. We now try to use only the clicker of the medium we are using at the time rather than just grabbing the closest one to adjust volume (they all work).

And then there are the gremlins.

foqus · 08-23-2009, 06:42 PM

I will try adjusting the subwoofer tonight...and I should clarify: the sound definitely changes/goes away when I put *pressure* on the floor in that area. It is not just from me standing in a certain location. If I put pressure down on my feet, it will change or come back, like as I rock back and forth on my heels. Thanks for the help you are providing!!

norsea · 08-23-2009, 06:48 PM

Quote:

Originally Posted by foqus

Hello all,

I am still under warranty, so I will have this checked out in a week or two, but here's the problem.

My 2007 19' International has a Sony sound system installed, with four speakers and a subwoofer. The unit has always had a buzzing sound when turned on and no music/tv is playing. I did bring it to one repair place, but they said it was because my switch had been on "Store" while it was plugged in to power and that it had something to do with the battery. I took their word for it and drove off. But, just yesterday, with the loud humming going on while I was preparing to start up a DVD, I happened to walk over by the sink, near the bathroom, at the foot of the bed, and the humming changed and then will altogether stop if I place my feet in exactly the right spot. Oh, and the buzzing changes *pitch* if I turn on certain lights.

Any ideas, or do you think my AS is in for a MAJOR re-wiring?

thx

marco in San Antonio

The following post should be of great help:

http://www.airforums.com/forums/f450...reo-36282.html

Bottom line: Install a ground loop isolator.

Jim

**moosetags** · 08-23-2009, 06:55 PM

Lucy has that same problem.

I cheat and do it the easy way. I just turn the selector switch to outside only.

Brian

wmarsha · 08-23-2009, 07:12 PM

ay yi yi-i gotta quit reading this forum...you guys are making me crazy. I am sure glad I bought an old airstream and don't have all these problems

! At least I ain't got an 8 track...

Gene · 08-23-2009, 08:41 PM

Some of the subwoofers have the controls on the side you can't see while you are on your stomach under the table looking at the damn thing. Then you have to unscrew it from the floor to get to the controls. There's a gain (volume) and a frequency control—turn them bothy half way down and see if the noise stops, then fiddle with them until to get close to the noise, and back off slightly. Or, cut the wires and that may solve it, or, put in a switch to turn it off or on (my solution along with adjusting the controls).

But, if it changes when you walk on the floor, it may be those gremlins who scream when you step on them. Or a bad ground somewhere, though underneath the floor sounds more like gremlins.

Gene

wayner61 · 08-23-2009, 09:34 PM

Jim's right. You need a ground loop isolator. The humming you hear is likely coming from almost all electrical items in the airstream because it is being introduced to the amplifier through the ground circuit. Lights, the converter, the water pump, the electrical circuits in the fridge and the fans can all induce noise. The ground loop isolator will stop virtually all of that.

The place you are stepping on in the bedroom is "probably" changing the impedance for some reason. It could be flexing something metal against the frame or really anything. There is a possibility I guess that a wire has somehow gotten pinched in that area. I don't really know if any wiring is run under the floor there or not. Someone that is intimately familiar with 12V electrical systems could probably do a little troubleshooting to find out for sure.

Good luck.