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Dead pixels appearing over time?

Discussion in 'Projectors, Screens & Video Processors' started by rjs1974, Jan 13, 2003.

  1. rjs1974

    rjs1974
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    Anyone on here had experience of an LCD projector developing dead or stuck pixels over time, i.e. ones which were not evident out of the box?

    And if this does happen, can it be repaired, or is it a permanent fault.

    Just been told by Sevenoaks that Sony will not exchange a projector unless it has 9 dead pixels or more, and they also say they can appear months later, and you are fcuked if they do!

    Is this the case - that I could think all is ok then pixels may die later and leave me with no comeback at all?

    I am receiving my HS10 later today.

    Thanks all.
     
  2. John_N

    John_N
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    Hi

    I would imagine that dead pixels appearing over time would be very very rare indeed.

    Think about it...

    dead pixels are caused by:
    1. Maufacturing problems.
    2. Premature failure of the pixel or driver due to mechanical shock.
    3. Premature electrical failure of the pixel due to electrical overloading, overheating.

    We've all owned laptop computers that tend to be banged around and abused and none of my laptops have developed dead pixels that weren't there when we got the machine.

    Given your projector is not likely to banged around and abused, mechanical stress is not going to damage the panel.

    Most dead pixels are there on delivery and are due to manufacturing problems. Therefore I wouldn't worry about your projector developing dead pixels over the course of it's lifetime.

    One thing that _could_ cause a dead pixel in a projector would be overheating of the LCD array that I suppose could damage a transistor junction and cause it to fail. An inherent manufacturing defect could cause premature aging and failure of a single pixel but if you keep your PJ well ventilated and use it sensibly I think you should worry more about whether or not you are going to win the lottery to be honest..

    I'm having my HS-10 delivered tomorrow.... yippeeee..

    Cheers
    John
     
  3. John_N

    John_N
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    PS.
    A dead pixel is there for good. It can not be repaired. You would need a replacement LCD panel.
     
  4. MAW

    MAW
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    Well, dead pixels are dead, but I get ones that take a short nap on my projector from time to time, but none are actually dead. When I see one the wrong colour, I put a bit of tape on the screen to check, and I've found none that have lasted a second turn on.
     
  5. snocrash

    snocrash
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    Here's an interesting observation:

    I've owned many high quality laptops with LCD TFT screens... Very occasionally a pixel will 'die' or 'stick' on the screen. Interestingly enough if you apply light pressure to the pixel thats broken, sometimes it fixes it.

    WARNING: DO NOT TRY THIS UNLESS YOU EXCEPT THE RISKS... I've thought about tapping or applying pressure to the actual LCD panel inside the projector to see if it'll fix a dead pixel. Obviously you'd have to know what you were doing and the warranty of the projector finished.

    Anyway... just a curious thought

    P.S. LCD panels in the projectors are on a flexible membrane usually.
     
  6. John_N

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    This would only work if the pixel in the laptop has failed due to mechanical shock wuch as would be encountered by a laptop during it's working life. Since a projector is not likely to undergo such shocks, I would imagine that any failed pixels would likely not be fixed by pressing the LCD membrane and I would certainly strongly advise against trying that!
     
  7. eyeMAJIC

    eyeMAJIC
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    Interesting thread. Here's the story of my Sony VPL-CS2.

    Bought Feb 2001, PC World (sadly, had to get it there, as that's where the business account was!)

    Got it home, ran RGB test on the PC. PERFECT. All colour pixels perfect.

    After 15 hours use, two vertically adjacent green pixels failed totally. Fortunately, these lie just outside the 16:9 zone, so don't affect DVD viewing. Put up a green background on a Powerpoint slide though, and the rectangular "hole" is impossible to miss!!

    After 30 hours, a green pixel near the centre of the screen got stuck at about 30% brightness. Only really noticeable during dark scenes with lots of movement (e.g. space scenes)

    After 40 hours, ANOTHER green pixel near the 30% one also got stuck.... much less noticeable; stuck at about 10% brightness.

    Now at 100 hours, and no more have appeared.

    Just before the 1 year warranty expired, I contacted Sony BPE Europe with the full story. They were utterly useless, and told me the responsibility lay with the retailer.

    So I duly returned it to PC World, who had (obviously!) no idea what the problem was. They agreed to send it to a "service centre".

    This was done, and took about 6 weeks. I plastered concise details of the faulty pixels all over the unit..... and when it came back, there was a very detailed report of the service that had been carried out (such as signal tests, cleaning filter etc.)..... but no mention of the pixels anywhere. And no surprises, they are exactly the same.
    Clearly, members of staff in such establishments are trained to ignore requests regarding dead pixels!!

    VERDICT: Well, it's put me off buying a 12HT or HS10 as an upgrade!! I would have thought that two adjacent totally dead pixels would qualify as a serious fault..... but obviously not in Sony's case.

    The only thing I can think of..... is that when the VPL-CS1/2/3/4/5 was developed, they were the only ones of their kind to use 0.7" panels (not the usual 0.9"). presumably in those early days, the failure rate on a more dense transistor matrix was higher.
    Good to hear the encouraging tales of pixel-perfect HS-10s that folks here have had.
    Think I'll probably go there eventually.
    Or maybe go the DLP road. ;)

    My 2p (sorry for the length!!)

    eM.
     

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