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A few questions about phosphor dots

Discussion in 'TVs' started by Zaichik, Aug 1, 2004.

  1. Zaichik

    Zaichik
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    I'm still wrestling with the retailer over the lines on my TV screen. However, after visiting another store and looking at lots of 28 inch screens, I'm beginning to wonder if it's even worth pursuing. Most of the screens I looked at seemed to suffer from the same problem to some degree (though not as badly as mine). The 32 inch screens did not, however (or not that I could see). The Panasonic engineer said it was down to visible phosphor dots.

    To help me decide, I'd appreciate some answers to the following questions:

    1. Are visible phosphors on the left and right of the screen par for the course on widescreen TVs? (Do they afflict screens of all sizes?)

    2. If so, what do they normally look like (mine look like a net close up, but merge into diagonal lines at a distance) and when are they normally visible?

    3. From how far away are they generally visible (I can still see mine from over 6 feet away)?

    Thank you for your help and patience. Sorry to labour this, but it's driving me nuts. Part of me is wishing I'd stayed in the safe world of the small, square screen! :(
     
  2. LV426

    LV426
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    Presume you are talking about CRTs - right?

    1: In general, the flatter the screen face, and/or the shorter the neck of the tube, the more likely these are to be visible. That's just an artefact of simple mathematical geometry (not screen geometry - that's something quite different). In practice, many modern TVs have flat screen, and, the larger the tube, the more effort is put into shortening the neck. So, the artefact you describe is, all other things being equal, more likely to be visible at larger screen sizes.

    2: A net or criss-cross grid, except on Sony tubes which have a vertical stripe structure instead.

    3: Depends on your eyesight, but with my specs on, I guess I'd see them at 6 feet.

    You could always save up for a large LCD, most (or all?) of which have a much finer grid structure than large TV CRTs.
     
  3. Phil55

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    Hi Zaichik,

    I have the exact same problem on my Philips 36PW9618 and I'm sure it's caused my hairline to recead at an ever increasing rate. I also went into a store to take a look at other 36 inch TV's and found the same problem to differing degrees. The sales man tried to tell me it was a bad reception (yeah right). For me they disappear when I turn pixel plus on or feed it an NTSC source. I'm trying to find a way to turn PAL signals into NTSC in case I just decide I've had enough and am willing to take the drop in resolution.

    Good luck
     
  4. Zaichik

    Zaichik
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    Thanks, guys. Any other comments welcome. It seems, though, from what you're saying, I may just have to put up with them. Shame really, because the set is fantastic otherwise. The only thing that is making me wonder if I should continue to pursue the matter is that I've seen two other sets of the same model that did not appear to be afflicted in this way. It may just have been that the pattern was not visible on what the shops were showing on their demo sets. A third set did have the same problem.

    I was wondering about this, because the only time I can't see the pattern is when I'm watching video recordings recorded in long play which, of course, are not as sharp as other pictures. The pattern is also less visible on analogue terrestrial than on a digital source. Would defocusing the tube slightly help (as in the fix for moire)?
     
  5. Phil55

    Phil55
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    One thing you could probably do in the store is just change the channel to view terrestrial TV and then see if you could spot the lines. I did this as I thought Comet where showing kind of bright slow moving scenes which my TV has no problems with. It's more the grey or flesh toned colours that can cause the problems especially at the sides of the screen when there are two people taking for example. I did see some problems on most models which strangely enough made me feel a little better but I can't help feeling if only....
    It would be interesting if defocusing a bit made a difference though I'm still trying to get access to my service menu as Philips tell me it's only for engineers.


    Phil.
     
  6. Zaichik

    Zaichik
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    Anyone else have any views on the questions I asked at the top of this thread?
     

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