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Registered
1988 560SEL sold:
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4,717 Posts
Discussion Starter #1
Squeaky noise coming from rear speakers (only) - I have noticed the following:

1. Begins about 30 seconds after car is started.
2. Noise modulates in correspondance with hazard lights when the hazard is turned on. Also, brake lights sometimes affect the intensity of the noise.
3. Noise is there even if the stereo is off.
4. Fader switch has no effect on the noise.
5. Particularly annoying at about 1200RPM
5. After about 10 minutes or 2-3 minutes on the highway, the noise goes away until the next time the car is started.

is it something related to the following thread (even though fader switch has no effect)?

htthttp://www.benzworld.org/forums/forums/thread-view.asp?tid=1197558&posts=5&hl=speaker+noise

What is puzzling me is that the noise is not constant but it goes away after a while. I will check the grounds (earth) and other connections. The problem started after I gently tugged an abandoned cellphone cord under the passenger seat to take a picture. The cellphone cord is routed under passenger side rear doorsill. Did I strip the speaker wire by doing that?

Thanks in advance for any opinions/suggestions
 

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Premium Member
1990 SEC
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4,102 Posts
I rather suspect it is a head-unit issue. Not a speaker issue.

Strictly speaking, it is difficult to have enough RF interference to drive the speaker. Possible, but very difficult. If you somehow strip the speaker wire, that is a different issue altogether, but it sounds different from RF noise.

By tugging on that old cellphone cable you may have pulled on the antenna cable and that can very easily cause RF interference and the humming noise you describe.

Power supply or antenna cable to the head-unit would be my first items to check.
 

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Registered
1988 560SEL sold:
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4,717 Posts
Discussion Starter #3
Thanks, will investigate those two issues.
Even though antenna RF seems most likely cause when I think about when exactly this problem started, the fact that the noise occurs even when the power is off might indicate power supply problem as well.



Just found another thread describing the exact same problem

http://www.benzworld.org/forums/forums/thread-view.asp?tid=1209041&posts=8&fid=12

will head over there and ask more questions.
 

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Registered
1984 280SEL AMG
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701 Posts
That isn't your altanator. You've prolly picked up a ground in your system, or a loose connection to the speaker/s.
 

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Registered
1988 560SEL sold:
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4,717 Posts
Discussion Starter #5
As far as know, there is no separate amp. I just read Mercbuff's result report on parallel thread and I think I should check the wiring more carefully. Also, I guess it's time to invest in a decent multimeter so I can do some diagnosis.

What is really puzzling me however, is the fact that the noise disappears after about 10 minutes.
 
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