# High pitched hum from all speakers



## Shimanek (Mar 23, 2012)

Hi,

i've been researching all afternoon trying to figure out why I have a hum coming from all speakers, but no posts seem to match what's going on. It's higher pitched, doesn't increase when I turn the volume up, and doesn't seem to be tied to anything I plug into the receiver. With everything unplugged, I still hear the hum. I've used a different outlet, with and without two different surge protectors. We just moved to a new house and this started, so the only thing I can think of is a) we broke the receiver moving, or b), there's something in the power outlet causing it.

Any ideas? The receiver is a Sony, with a 2 prong cord.

Thanks!


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## wgmontgomery (Jun 9, 2011)

From what you wrote, it seems that you've already done a good job of troubleshooting the problem. What I find strange is that you describe the sound as a* high *pitched sound; usually ground problems (the most common source of "hum") are_ low _pitched. Although it may be some other problem, the receiver _may_ be broken. Here are a few things that come to mind that are NOT caused by a broken receiver:

1) Check the inputs/outputs on the receiver. If you have a video source connected to an audio input, it will cause a "hum." Make sure that your VCR, DVD etc. are properly connected...composite video is usually a yellow RCA plug; make sure it's not connected to an audio input. If everything is connected via HDMI you can omit this step.

2) Do you have a subwoofer in the system? There should be a "ground lift" switch on the sub that may fix the problem.

3) Try disconnecting the cable from the TV, VCR etc. By cable I mean "cable TV" cable.


If you've disconnected _everything_ from the receiver, and it is still making a high pitched sound, something may be broken as you suspect. Take a look at the things listed above and let us know if the problem persists; we'll try a few other things before concluding that your stereo is broken. Good luck!!


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## Shimanek (Mar 23, 2012)

Thanks for the quick reply. I had tried unplugging everything from the receiver and power supply, and the pitch was still there. My last resort was to get out my wife's old receiver and hook it up, and when I did just now, the pitch was gone. I'm familiar with the lower pitched hum when you've got some sort of grounding interference, but this one is higher.

So I guess it's the receiver. It's not an expensive one, but has more power and functionality, any chance I could diagnose what's wrong with it?


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## wgmontgomery (Jun 9, 2011)

Shimanek said:


> any chance I could diagnose what's wrong with it?


Since connecting a second receiver fixed the problem it PROBABLY is the receiver. Something may have gotten broken in the move as you suspect. As for diagnosing the problem, you could check the general service thread to see if it's a common problem:

http://www.hometheatershack.com/forums/general-service-technical-information/

I didn't see anything, but something may be lurking there. Perhaps if you post the exact model someone may chime-in who has had a similar problem?

Another idea is to contact Sony if the unit isn't very old. Sony products are usually quite reliable; most problems are solder connections. It may be worth it to take it to a repair center. I would NOT recommend opening-up the unit and attempting to repair it yourself. Good luck!


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## RBTO (Jan 27, 2010)

One more check, and I'm working under an assumption that your receiver is ok, disconnect all inputs and all but one speaker. Make sure that one speaker is connected correctly. Do you still hear the hum? What happens if you introduce an audio source like an FM station audio (with just one speaker connected)?


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