Audible hum from HD TV

Crashtard

This started after I updated to a HD receiver from comcast and hooked up my box with the HD component cable to my tv. I'm assuming that it has to do with the ground loop, but I don't want to spend the apparently required $60 to buy a little adapter to take care of the problem. Anyone have a good solution to this problem, or other ideas what could be causing it?

useless4

/make sure you have the right audio outputs to the right audio inputs. I have seen people hook up the orange audio output to one of the normal analog input channels (red and white) and it causes a great buzzing.

Crashtard

I'm actually just using a red/white connector for the audio. I actually hadn't thought about check to see if it has the orange output on the box, or the tv. I'm going to go check that now.

CF1

I guess while you're looking, make sure the audio red and the video red aren't switched. You probably would be complaining about the picture if this were the case, but hey. The audio red generally is a thinner wire than the video red.

Crashtard

That's definitely not the case. I did check that make sure earlier today, but I'm pretty sure the video would be wonky if that were the case. I'm half tempted to unplug one just to see what it looks like.

1ddqd

Is this hum coming from the speakers and does it scale with changing the volume, i.e. gets more noticeable if you turn up the volume or less noticeable if you turn it down?

Hardleft_335

Mine has a hum when you you the brighter setting/are seeing an all white screen. It comes from the back of the tv.

Shadowfire

Hardleft_335 wrote: »

Mine has a hum when you you the brighter setting/are seeing an all white screen. It comes from the back of the tv.

Power supply issue..?

1ddqd

Or backlight issue.

Hardleft_335

I just dont use the really bright setting.

Crashtard

1ddqd wrote: »

Is this hum coming from the speakers and does it scale with changing the volume, i.e. gets more noticeable if you turn up the volume or less noticeable if you turn it down?

This is definitely the case.

1ddqd

Then I'm guessing it's noise from the power, either a wire too close to the audio processing board, or just bad board design. What specific model is your TV?

SiliconStew

Probably from running your audio cable next to your power cable for some distance. If you're using those thin, cheap, and poorly shielded red/white audio cables, they can pick up the 60Hz frequency from the powerline. More common for unshielded speaker wire to pick it up. Try to keep your signal cables as far from power cables as possible and if they need to cross, do it at right angles. Hard to do behind your tv, so better shielded cables might work.

Also, try to plug the tv and reciever to the same outlet or as close together as possible to try and reduce ground loop effects. Of course if one device uses a 3-prong plug and the other a 2-prong, your going to have problems anyway. If so, you could try running a ground cable to connect the metal chassis of each device together. Even after all that, you still might be getting a ground loop from Comcast's coax cable. But I would think you would see video effects as well if this were the case.

Crashtard

SiliconStew wrote: »

Probably from running your audio cable next to your power cable for some distance. If you're using those thin, cheap, and poorly shielded red/white audio cables, they can pick up the 60Hz frequency from the powerline. More common for unshielded speaker wire to pick it up. Try to keep your signal cables as far from power cables as possible and if they need to cross, do it at right angles. Hard to do behind your tv, so better shielded cables might work.

Also, try to plug the tv and reciever to the same outlet or as close together as possible to try and reduce ground loop effects. Of course if one device uses a 3-prong plug and the other a 2-prong, your going to have problems anyway. If so, you could try running a ground cable to connect the metal chassis of each device together. Even after all that, you still might be getting a ground loop from Comcast's coax cable. But I would think you would see video effects as well if this were the case.

The cables I'm using right now are a pretty thick cable, probably a 3/16" cable overall. The cable was close at one point where they were running, and I moved them away from each other. Now they are about 14" or so apart. The box and the TV are both plugged into the same surge protector/power strip, and aren't more than 1 plug apart from each other. I don't really see a place on my TV where I can access the mettle chassis, so I don't think that's going to be an option unless it becomes the ONLY option. I do think though that the cable box is a 2 prong plug, where the tv is a 3. Should I adapt the tv down to 2?

Edit: Also, thanks for all the ideas so far. I definitely appreciate all the help so far.