Panasonic Plasma TV Hum/Whine?

Discussion in 'Televisions & Displays' started by mtflynner, Oct 12, 2008.

  1. mtflynner Audiophyte

    mtflynner
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    Have a 15 month old Panasonic 50" TH-50PX75U and have noticed a high-pitched hum/whine that seems to be triggered by whatever's shown on the display. Does not seem to be tied to the audio, as the hum/whine happens when muted; the hum/whine also occurs regardless of source (cable, DVD, etc.). On DVDs or shows where the movie cuts back and forth between two scenes, the TV will repeatedly hum/whine on the one scene but not the other.

    Anyone seen/experienced this type of issue before? What causes it? Any way to address/fix? What's Panasonic like to deal with if warranty is expired?
  2. snappy_snoopy Audioholic

    snappy_snoopy
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    In my experience high pitched hum and whine as you put it comes from switch mode power supplies where the inductor windings have come loose and vibrate in the audio frequency range. When i built a switch mode power supply for a university project i noticed this hum when i did not wind the inductor windings tight enough. This is also a common problem in laptop and other small power supplies.

    It could be that for some reason on scene changes your tv requires a sudden burst of power, and this triggers the inductor to vibrate !! Then again without knowing exactly how the power supply is build and what type of switch mode converter is being used i can also not comment on whether this is the case. Just some speculation on my part.

    Hope that helps :eek: Dont know about the panasonic service department either much help i am :rolleyes:
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  3. bandphan Banned

    bandphan
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    Has the set always done this? Panasonic's cs is priddy good, and as with most manufactures will provide some limited tech support via the phone. Have you searched through the owners thread at avs forum?
  4. walter duque Audioholic Samurai

    walter duque
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    Unplug tv and cable box from outlet for at least 1 hour, this will discharge the powersupply. I have a similar problem with my pioneer have to do this about every 6 months.
  5. walter duque Audioholic Samurai

    walter duque
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    Also check if you added a new appliance to the same circuit. Also plug tv into a different outlet. could be your outlet to who knows. Sometimes people panic but it could be an easy solution. Good luck...
    Last edited: Oct 25, 2008
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  6. sneakystiffler Audiophyte

    sneakystiffler
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    Same issue

    I have the same issue with the same model TV. Mine was still under warranty and the power board was replaced along with another board and it still makes this noise only on certain scenes. It seems to only happen on scenes with a lot of white or lighter color in them? The company working on my TV under warranty took my TV to their shop last wed and still can get it to reproduce the noise.
  7. PHANofPHUNK Audioholic

    PHANofPHUNK
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    bad voltage regulator?

    may be ground loop
  8. Jgun Audiophyte

    Jgun
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    58" Panasonic Buzz/Noise

    My 58" Panasonic justed started to do this. I noticed that I can get the level of the noise to change when I adjust the "picture". The buzz/hum does change as the scenes change, but they get louder when I increase the "picture" all the way and quieter when I turn the "picture" down all the way. This sucks, my plasma is 21 months old.
    Jgun,
  9. nibhaz Audioholic Chief

    nibhaz
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    Are these sounds emanating from the TV itself, the TV’s speakers, or being transmitted to your sound system via a cable?
  10. solomr2 Full Audioholic

    solomr2
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    Any follow-up on this?

    My 50" Samsung Plasma is doing the same thing. It happens on bright pictures, stops on dark pictures. The power is running through my PureAV console, and I tried plugging the TV direct into an outlet, but it didn't help. My TV is out of warranty now, so I can't really call Samsung about it.

    Anyone have any suggestions?
  11. Adam Audioholic Jedi

    Adam
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    My Panny does it. I thought that it was normal.
    Adam,
  12. solomr2 Full Audioholic

    solomr2
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    Is it? I can't imagine this is normal, it is so loud, I can hear it from 12 feet away. It is loudest when there is a lot of white on the screen, but it is completely quite when the screen is black.

    I read one post that Samsung had some kind of silent tech update and was quitely replacing power transformers on various models of HDTVs, but my FP-T5084 was not specifically listed.

    It always had a bit of a hum, even when it was brand new. But it seems to have gotten significantly louder in the past couple of months. It is making me crazy.
  13. nibhaz Audioholic Chief

    nibhaz
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    Based on the anecdotal evidence you‘ve provided about the hum increasing with a white screen, I would venture to say that your hum is most likely power supply related.

    As to a solution...tech support is all I got:(
  14. solomr2 Full Audioholic

    solomr2
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    Yeah, I'm afraid so. But judging from what I read so far tech support tends to be a dead end.
  15. rixlt1 Audiophyte

    rixlt1
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    I just stumbled upon this thread after going 'round and 'round with Best Buy on this problem. I bought the extended warranty on my TV...and the Geek Squad came out this morning and replaced the power board on my Viera 42", but it still whines/hums. They called Panasonic and Panasonic told them that there was nothing else that could be done and that this is normal for a plasma TV. I've had this TV since 2007 and it just started making this noise 2 months ago!!! Now, Best Buy will not replace my TV (as the warranty states) because Panasonic has told them that this is a normal noise. I told them that if the TV was making that noise when I bought it, I would've returned it within the 30-day return period. Just thought I'd warn you guys, that even though you have a warranty, it doesn't mean they'll fix this problem. I'll think twice about buying another Panasonic product or ANYTHING else from Best Buy.
  16. TLS Guy Audioholic Overlord

    TLS Guy
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    It is close to normal. TV's have been prone to this for the fifty years plus I can remember. White scenes take much more power. Also there are high frequency oscillators in TV, that can induce all kinds of high pitched noises and other sounds from inductors in power supplies and other places.

    It is very common and hard to cure.
  17. rixlt1 Audiophyte

    rixlt1
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    What's weird with mine is that the sound is more prevalent during darker scenes.
  18. Riedy09 Audiophyte

    Riedy09
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    My 50" Panny has always made the hum, but on more when the screen is depicting a light scene. But, it is all OK when the A/C turns on and drowns out the noise. FWIW, my 60" Pioneer makes the Panny seem ultra quiet.
  19. godswill Audiophyte

    godswill
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    My tv does the same

    I have the same model, but as i plugged my computer to the tv to test out the on which colors it made the whining, it turns out that darker colors would make it whine loudly. Like black, or dark red, or green etc.

    It's not the speakers, and when i go to the back of the TV it comes from what looks like the main board or behind it. Basically the sound comes from the middle of the back of the tv. Maybe a little to the right of middle when looking at the tv. I've read that maybe it's the color wheel? or something like that.

    Anyone know what is causing this whining noise? Or how to fix it?
    :confused:

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