High-Pitched sound from new TV (1 Viewer)

[SamE]

I posted this to a Newsgroup about a week ago and didn't get any response. Maybe someone in here might know what the problems is.
I bought a Panasonic CT-36HX41 close to 6 weeks ago. When the TV shows a very bright image on the screen, it makes a high pitch sound from the back of the set. For example, images out-side when it is sunny, brightly lit screens (stuff like that). It does not do it when the image is dark, such as scenes at night and in-doors. I watched "What Lies Beneath" last night. There is a lot of bright scenes and white in the movie. I could hear this high pitch sound during all of that. The only time it didn't make that sound was during parts of the movie that were out-side during the night. This 36HX41 replaced a defective sony 36FS12. The sony never made any sounds like this when showing bright images. With the volume up at a normal level, you can still slightly hear it. With the sound all the way down, you hear it more. It is not coming from the speakers, but from the back of the set.
I'd would like to get an idea of what this could be before calling Panasonic and a repair tech.
Thanks,
Sam E

 

[RoyGBiv]

One possibility might be a noisy audio transformer. I've had two TVs, a Sony and a Mitsubishi, with this problem when new that had to have the transformer replaced. Noise from the transformer would not be coming from the speakers but from where the transformer is located in the chassis. If this noise goes away when you mute the sound (not just turning the volume all the way down -- that may not turn off the audio), then that's the problem. If not, I don't have any other ideas. But, if it's loud enough to bother you, you should have someone come check it.
SMK

 

[MickeS]

I'm 99% sure this is due to a faulty power supply. When the screen goes white, it draws more power, that's why the noise is heard then. This usually only seems to happen on really cheap TV's or old ones. I'd take it back and have it warranty replaced or repaired.
/Mike

 

[GaryM]

Congratulations - you are in the minority who can still hear the 15.75 Khz sweep frequency. Good luck in finding a service rep who can also hear it (some will privately think you are nuts).
The high voltage flyback transformer is the usual culprit. I have resolved some such problems by spraying a good high voltage shellac onto the coil, saturating the gap between core and wire, but only on my own, no-longer-under-warranty equipment. Get the manufacturer to fix or exchange the set if possible.
Take care of those ears - a few close-range rock concerts, and you'll never hear those high frequencies again.
Gary

 

[SamE]

In reply to Steven Kempner:
It does it with the volume all the way down or muted. It does not matter.
MickeS:
A friend of mine said that he thinks it has to do with all the electron guns firing at the same time. It uses more electricity through a power supply or transformer and the extra juice is what I'm hearing.
GaryM:
Since I am not a super-tech on TVs, I do not know what a 15.75 Khz sweep frequency is. Is it common for TVs to make this sound? I had a Sony KV-36FS12 for 6 months and never heard this sound from it.
P.S. I am a music major in college and have always had very good hearing, including being able to hear low and high frequency others can't. I hope this sound can be fixed, it's quite annoying.

 

[l e j u n]

I have had this problem for about the past year or so. It drives me nuts! Except I hear it at all times and even worse when a brigh white screen comes on.
I first started hearing it on my cheap 27" RCA TV after about a year of having it. No one I know can hear it like I do but some know what I am talking about.
I thought it was just my TV at first but the I started to relise that it was on every TV I was around (imagine what it feels like in Best Buy). It really sucks and has seriously affected my viewing enjoyment.
I tried buying a new TV. I bought a Tosh 36" direct view. Didn't work. Still heard it. I returned it. I suffered with it for a while. Not even watching anything for a while and then finally getting a pair of headphones (can't even enjoy my dts setup ;_

.
I finally just purchased a Tosh HDTV and I have yet to hear the noise. I have had it for about two weeks now. I now fear that my time with this will be limited though.
l e j u n

 

[Joe D]

I had a problem similar to this in my 25" RCA TV. My question to you is have you calibrated the brightness of the TV. After I calibrated my TV, I could no longer hear the noise, so it was that the brightness and picture were way too high.
------------------
Joe Dahlen
"Take hold of the flame, you've got nothing to lose, but everything to gain."

 

[l e j u n]

I don't know if you were talking to me but, yes, I did calibrate my RCA.
l e j u n

 

[SamE]

I have a 27" Sony and only hear a high-pitch sound when the TV is turned-on. This only last for a few seconds. I also had a Sony 36FS12 (which the HX41 replaced) for a few months and ever heard this sound with it either. Someone suggested to turn down the contrast or picture values to see if that helps. Well it does help, but then the image is so dark that you can't see it. The only calibration I have done is with my eyes watching DVDs and cable and also using a THX calibration on a DVD. I have not bought a V.E or Avia disk as of yet or had an ISF calibration. I think there is something definite wrong with this set and that this sound should not be there. I have been able to have other people hear it as well. I am going to have a tech look at it next week.
-Sam E