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Mysterious Video and Audio "Hum"

N

Nealio

SatelliteGuys Family
Original poster
Dec 27, 2005
41
0
KY
Hi, I am having a strange problem. When I hook up my receiver to my PC using RCA audio cables and either S-Video or Composite video, I get a loud audio hum and strange looking video waves that pan from the bottom of my screen to the top. This doesn't happen when I hook it up via coax cable--but I want to use my S-Video and RCA audio cables.

I tried a different receiver I have at my house (thinking that maybe something was wrong with the one I was using) but it did the same. I then hooked up my PS2 to the computer via RCA video/audio and it played without any hums or anything.

Here is a video I uploaded of my problem (I increased the brightness so you could easily see what's going on).

http://s5.photobucket.com/albums/y1...iew&current=CrazyAudioHumandVideoWaveXviD.flv

Like I said I have two receivers in my house and both receivers run just fine without these problems on my TVs. One is hooked up with coax and the other with RCA audio/video cables.

Also I had a problem like this months ago but I figured it out... it was doing basically the same exact thing. I have basic cable as well and when I had that plugged in to any TV, it would make all of my satellite-equipped TVs have these "hums." Whenever I unplugged the basic cable coax cable, they would go away. I don't have "cable tv" hooked up to any TVs right now though so I am puzzled on this one.

Anyone have any ideas why this is happening? Thanks for reading!
 
Sounds like a bad cable. Plug all three in to get the hum, then unplug each cable by itself to see which one it is.
 
I forgot to mention but I've already tried 3 different cables... they all do the same thing. It's only the RCA audio cables though that make the audio and video hums.
 
Last edited:
Anybody else have any ideas? It used to work just fine until about a month or two ago. I don't know what would've changed it.
 
That's a 60hz ground loop. You have a grounding problem. Are the grounds in the AC sockets correct?
 
I'm not sure if my AC sockets are correctly grounded gdarwin. Is there a simple way I can check?
 
Go to Home Depot/hardware store, and get a "AC polarity checker". Don't know the actual name for it.
 
Okay I'll look into that. Suppose it is the problem (which it does really look like if after doing some research), would I have to get a technician out here to fix it... or is it something easier to fix than that?

Thanks for your replies!


Oh also... should I try to move my computer to the other receiver and see if it makes any difference... or do you think the entire house has a grounding problem?
 
Sometimes and outlet will lose a connection - the ground wire could have come loose. I have had two outlets where one of the sockets quit working and pulled it out to find that a wire had popped loose. I changed out all my outlets and made sure to wire them to the screw terminals rather than just shoving the wire into the holes they give you.

Get the tester and see how your outlets test out. Some testers are smart enough to tell you if you have an outlet problem or a house problem.
 
Ground loops go well beyond that.

Are all the units (TV, STB and PC) plugged into on the same circuit or behind the same surge protector?

My guess is that you have a surge protector on the PC and not on the Satellite/TV system so the grounds are different.

And let's not forget that the ground that should be installed on the dish may not be run to the same place the AC is grounded entering the house (as it should be - but codes sometime allows only a certain distance to a ground).
 
HDTVFanAtic I was actually just doing some research on this and you are right, I had a surge protector on my PC but not satellite receiver. I tried moving some cables around and I used a different outlet to hook up the PC and satellite receiver to the same surge protector. I helped out a lot. The video waves are gone, but some audio humming is still there. It's only about half as loud now... but it is still a nuisance.

I tried hooking everything up using different outlets but they all produced basically the same thing... some made the hum a little louder than others though.

What I thought was kinda strange is when I had the TV Tuner program running on my computer with the receiver hooked up to it via RCA cables, but without even plugging the receiver in, there would be that audio hum. Then when I go to plug in the receiver the hum gets louder. Of course unhook the RCA cables from the receiver to the computer it doesn't make any humming noise. I don't know much about ground looping and whatnot, but is there anything I can manually do to try to fix it? Like I said, at one time (a couple months ago maybe at the most) it was running just fine without any humming on the same setup.

Thanks for all the posts!
 
Ground potential pgoblem

It sounds like you have different grounds for the house and the sat system. this will also cause a grounding problem. The give away for me on this is the fact that you had the same problem with cable. The cable system will in allot of cases have a ground out at the local distribution box. The ground loop noise went away when you disconnected the cable shows a difference in ground potential. It sounds like that in the past few months the ground for either the house or the sat has gone bad. This could be more of a problem than you realize. If you can't find the problem w/ a simple 3 light ground tester it's time to call an electrician. Different ground potential can cause AC to be carried on the ground causing an electrical shock problem.
 
Nealio said:
Anybody else have any ideas? It used to work just fine until about a month or two ago. I don't know what would've changed it.
Click to expand...

I personally think you may have stumbled onto an even bigger issue. I also started experiencing the same problem in my theater a month or so ago but it seems to be only a particular channels. Trust me, it not my equipment, I have thoroughly been through that already.

Does your problem exist on ALL channels or just a couple? Mine seem to be limited to a few local broadcasts and the sound does not exist OTA.
 

It sounds like you either have to break the ground with a surge protector at every possible place (including rg6, cable, telephone etc) that somehow makes its way to your TV and PC or make sure they are all grounded at the same point.

Remember if you have a second TV and IRD, that will also have a ground going to the switch (or the lnb) and back down to your main set if you don't deal with it on the RG6 coming to your main unit.

This is exactly the reason why there is supposed to be a common ground in the house.
 
Okay thanks again everyone for your posts. I am going to do a couple more tests tomorrow. If I make any progress I'll post it.
 

My tv makes the same noise when i plug video outs into audio ports or audio outs in to video ports.
 
moltomateo said:
My tv makes the same noise when i plug video outs into audio ports or audio outs in to video ports.
Click to expand...

If only my problem were so easy... thanks for the info though. I tripled checked just now to make sure everything was plugged in right and yeah it was
 
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