Vibration effect on TVs? Anyone else?

Discussion in 'Displays' started by John_Pang, Jul 8, 2003.

  1. John_Pang

    John_Pang Extra

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    Has anyone had any problems with vibration and their TV monitors? Specifically direct views? I have a Sony KV-34XBR800 widescreen direct view monitor with a
    Def Tech CLR2002 center channel spkr sitting on top of it. During loud passages at reference level SPL (80 dB)
    I can see interference (look like dark “waves” on the screen) in bright areas of picture i.e. sky. It is very apparent on the CA: Full Throttle trailer, Tears of the Sun during the bombing attack and the riot scenes in Dark Blue, for example. I placed some Monster Cable Vibration dampers under the speaker but it did little to change the situation. Is this normal for direct view TVs, or is it something that I should have checked by a Sony tech under warranty? I had no such problems with my previous 41” Sony RPTV, but on that set the speaker and CRTs are separated by a few feet. I want to avoid having to build a shelf to place the speaker on behind the TV for a # of reasons, primarily speaker height will be incorrect, blocking of my backlight setup, and the extreme depth of the TV.
     
  2. Allan Jayne

    Allan Jayne Cinematographer

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    The shadow mask inside the picture tube may be jiggling from the vibration and this can cause discoloration of the picture. Sony's are more sensitive to vibration because the shadow mask has long vertical strips that are prevented from sidewise or twisting motion only by two or three widely spaced horizontal strips.

    There may be enough electromagnetic forces coming out of the speaker unit atop the TV to affect the picture tube.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  3. Jorge M

    Jorge M Stunt Coordinator

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    It might also be an electrical current issue. If you lift the center channel off the TV, does it still happen? If it does, try plugging in your amp, sub, or both to a different circuit.
     
  4. Cliff Olson

    Cliff Olson Stunt Coordinator

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    I had this issue myself, and it went away with good quality cables and a Monster HTS-2000 surge protecter. I think the Monster surge protecter might have been the main reason, but I bought all the cables and surge protecter at the same time. In fairness, the center channel may NOT be the cause. It could be from the mains, or if even if you have a sub. Mine did it when listening to my stereo at high volumes (the center channel was off). I never isolated the exact cause, but I could care less since it's now gone!
     
  5. JimmyK

    JimmyK Second Unit

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    Sounds like magnetic interference from you center channel speaker. Even though it may be shielded, it my not be shielded enough to prevent problems, especially during higher volumes like you descibed.

    Moving the center further from the crt (if posible) should solve your problem.

    JimmyK
     
  6. John_Pang

    John_Pang Extra

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    Thanks for the advice guys. After looking at the symptoms a bit closer, I think it is indeed magnetic interference, not vibration. The speaker is shielded, but when driven hard the speaker is creating a mag. field. I am going to be looking into building some sort of shield. Lifting the speaker a couple of inches off the set has helped but not alleviated the problem. I know that a shelf for the speaker would do the trick, but it would create some other problems that would need to be overcome.
     

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