interference on an LCD TV

[Mikey]

I recently moved into a new house. In our bedroom, we have the coaxial cable outlet and the electrical outlet mounted very close together (~2 inches apart) on the wall. When we moved in, we set up an older 13" tv in this room. We noticed that the TV would often give off a very high pitched whine, that would build up in intensity over 2-3 minutes. It might last for another 2-3 minutes then go away. Another 15-20 minutes later, the whole thing starts over. Changing the volume on the TV or changing the channel does not help at all.

I first thought the TV was malfunctioning, so I decided to purchase a new 19" LCD TV and install that, wall mounted. Well, this new TV has the same problem. Someone suggested that the coaxial cable and the power cable are too close together, and that the cable may be picking up interference from the NMD wiring inside the wall, or vice versa.

Does this sound reasonable? If so, is there any filter that I can install on either or both wires going into the TV?

Any help or advice appreciated.

Thanks,
Mikey

[Mr T]

First you may have 2 problems. on your tube TV (making an assumption) did the sound come from the back of the TV or the speaker? It may be very hard to tell.

There is a large high voltage transformer inside your TV (makes about 25k volts). They operate at a high frequency (about 1-5khz) Sometimes that transformer starts to vibrate (sing). It can be a sign of something starting to go but ive had tv's do that for years and still work. As the tv heats up the intensity or how often it does it may change.

Your LCD tv does not have the same setup. There may be a high voltage supply in there but it just powers the backlight for the screen. Ive never heard of them singing like that before.

If the sound is coming from the speaker on both sets, try unhooking your cable and hooking up a dvd player or vcr (not hooked up to cable) see if the sound is there. Your coax is highly sheilded and its unlikely that being close to your power will cause a problem. Residential electricity runs at 60hz anyways.. if it causes any noise it will be a low pitch buzz or a flicker on your screen that occurs once a second.

Also try it plugged into another circuit with and without coax and see what happens. You can also use a long extention cord from elsewhere in your house if you dont wanna unmount the TV.

Let us know what you find.

[Ohm1]

I guess we will never know!?