Why does text displayed on my TV make noise?

Factual Questions
1

I have cable and don’t have any reception problems. I also have my TV hooked up through my stereo speakers. I don’t have any sound problems either, except when a large amount of text is displayed on the screen, ie. the end credits after a movie trailer. When a large amount of text is displayed, my speakers play a distorted humming noise. Same thing if I watch through the TV speakers instead of the stereo. It doesn’t happen if I turn on closed captioning, nor does it happen if I’m watching a subtitled DVD.

What is it about text on the TV screen that makes the TV hum like that? I would understand if I were using rabbit ears, but we’re talking ghost-free, crystal clear cable TV. (As clear as cable can be, anyway).

2

For what it’s worth, I too have a TV that caused that problem and it’s not hooked up to any stereo. I work for a cable TV company…I’m not a field tech, but I asked someone here who is. He referred to it as a “synch clip” and said that most of the time it can be resolved through simply fine tuning, but some tuners are so lousy that they can’t be adjusted properly.
He wasn’t able to adequately explain to me what a “synch clip” is, but evidently something different gets embedded in the video outside the normal range that the tuner looks at for video and the tuner is seeing something it can’t interpret properly where it thinks there should be audio.

I haven’t gotten around to “fine tuning” my TV yet to find out if the problem goes away.

3

Sam G. has spoken. (3rd item on the list.)

Note that freq. it is a problem with the source being too strong (“white”). But if it happens on different channels, then it’s your set.

4

So it’s the TV? Great. A brand new 36" Toshiba and there’s something wrong with it.

Thanks for the info guys.

5

If this is a new TV I’d take it back. You may have to ask for another brand. I have the same problem with a Sony TV that is about 25 years old. I believe the problem occurs when the original signal is rebroadcast either on channel 3 on a VCR or on cable. The white lettering offers too much contrast such that high frequency harmonics are generated and because they were not filtered out properly by the VCR or cable company it bleeds into the section of the spectrum that carries the sound. Newer TVs should be able to cope with this. I bet your TV does not make this sound for signals taken directly from the air. I get around this by connecting the line out from my VCR to line in on a hi-fi system (Bose WaveRadio) turn the sound off on the TV and always use the tuner in the VCR. But you shouldn’t have do this. … take it back to the store.