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Toshiba MT500. A Common fault for all DLP projectors?????????

Discussion in 'Projectors, Screens & Video Processors' started by StuartBay, May 21, 2005.

  1. StuartBay

    StuartBay
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    Background

    After the initial elation of viewing my new projector, a Toshiba TDP MT500, I become aware of an annoying problem. If you imagine the 16:9 rectangular image, below and above of the rectangular image are bands of faint light which are obviously not part of the projected image (this problem is only apparent when viewed in low light), since noticing this problem I contacted Toshiba who advised that it was a fault and that it should be returned. I was consequently informed by one of Toshiba’s technicians that “this was not a fault and that all DLP projectors suffered from this “dump light” problem in varying degrees”.

    I have to say that I was stunned by this comment and to be honest I simply didn’t believe him, after all no self respecting company would knowingly sell defective goods; would they? Anyway, Armed with statement I contacted Toshiba again, they conceded that there was a fault and replaced the unit. The replacement had exactly the same fault. I am now in possession of a third unit, which again has the same fault. After again informing Toshiba of the same fault, they informed me that there is a batch fault and they were waiting conformation from Tokyo.

    Having had 3 units that were manufactured over a period of a year. I am somewhat doubtful if this is in fact a batch fault.

    I would be very grateful for any comments about “dump light”, especially from MT500 owners.

    StuartBay
     
  2. underpar

    underpar
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    I have an 18 month old mt 500(original model) with 350 hours on lamp. It has given me excellent service thus far. I have recently teamed a Samsung HD745 using a 10M Lindy DVI cable and have noticed a cleaner smoother image. Don't quite understand your problem but I havn't experienced any.
     
  3. Gary Lightfoot

    Gary Lightfoot
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    It sounds like light overspill - I seem to remember seeing a Toshiba that was using a 4:3 chip but only a 16:9 portion of it, so the rest was not being used. RTFM who was having it demo'd at the time noticed some light spill above and/or below the projected image and that's how we then realised a 4:3 chip was being used and not a 16:9 DMD.

    The image wasn't completely filling Jeffs screen, so that's why he noticed it, as the area above the image showed the ligtspill against the white of his screen. It's not a fault if that's what you're seeing, but just stray light reflecting off of the unsued portion of the DMD. If you were to project a completely black screen, the whole panel would look the same shade of dark grey and 4:3. If you can, zoom the image as small as posible and project black so you can see the shape of the dark grey. That will tell you if it's a genuine 16:9 chip or not.

    Having looked at projector central:

    http://www.projectorcentral.com/Toshiba_TACP-TDP-MT500.htm

    It suggests the chip is 4:3 XGA (max 1024 x 768), but 16:9 native (1024 x 576). So, what you're seeing is unused reflected light from the unused area of the 4:3 DMD. I think it should have been masked internaly but the only way for you to remove it is to have a good masking materal around the screen and dark walls behind it. Black felt would absorb the extra light but probably isn't practical.

    You could try making an oblong shape in a piece of card (only the top and bottom need to be close to the projected image) and fix that to the lens so that it cuts off a lot of the stray light. You won't get it perfect because the edges will be fuzzy (being outside of the focal plane of the lens), but if it's close enough to the black border of your screen you will lose most of the unwanted 'dump' light as they call it.

    Gary.
     
  4. RTFM

    RTFM
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    4:3 DLP and LCD projectors all suffer from the overspill of light when you are using their 16:9 setting (if they have one, most do ) but there should be no overspill when using projectors with true 16:9 panels.

    Jeff
     
  5. Gary Lightfoot

    Gary Lightfoot
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    I wish I could be as concise as you Jeff. :)

    Gary.
     
  6. StuartBay

    StuartBay
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    Your comments on my problem are helpful, it is my understanding that the MT500 is a true 16:9 chip so I should not see any light.

    I should clarify the shape of the light spill.

    Starting from one end of the top of the screen there is a narrow band of light, about 25mm high, it extends across to the end of the screen and is about 300mm high. The bottom of screen is a mirror of the above.

    I take on your points about the chip but I would have expected to see the light spill uniform, not this elongated trianlge
     
  7. RTFM

    RTFM
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    The Toshiba Gary and I saw from Anders + Kern last year sometime had some asymmetric lightspill that the rep said was a fault with his demo unit.
    Haven't seen another specimen of that model so not sure if that's common.

    Jeff
     
  8. Liam @ Prog AV

    Liam @ Prog AV
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    MT500 is a 4:3 DLP chip that never uses the full 4:3 arrangement, just the 576 lines in the middle to effectively make a 16:9 1024x576 resolution picture but still on a 4:3 chipset. The light is basically "leaking" above and below the active portion.

    http://www.dlp.com/dlp_technology/dlp_technology_products.asp

    Have a look at the 576p chipset (3rd line down, right hand side) - even the current "true" 16:9 chip is essentially a converted 1024x768 chip with potential for lightspill at upper and lower extremities.

    As for the triangular shape of the lightspill I don't know. The MT500 I used had a definite lightspill at top and bottom but not triangular as I remember. Unless your projector is not square to the screen?
     
  9. StuartBay

    StuartBay
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    As far as the shape of the light spill, yes the PJ is square to the screen.


    I am beginning to think that I have been a victim of advertising. I was under the impression that it was true 16:9. I have another post which is titled Toshiba MT500 or M8 (should be MT8). It gives some background to my dealings with Toshiba, they have very helpful with this problem.


    What are your views on the options.

    I am tempted to go for the MT8, but if it is also not a true 16:9 chip I have the potential for the same "light spill" problems.

    Also do you consider a swap out for my new MT500 for a second hand MT8 to be a good deal.
     
  10. Liam @ Prog AV

    Liam @ Prog AV
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    The MT500 is true 16:9 in it's resolution and aspect ratio, it just uses a 4:3 chip to achieve this. Many 576p projectors are the same, just don't show quite so much lightspill as the Tosh does.

    The MT8 is a lovely projector, if straight swap then I would go for it. Also I would download the latest InFocus Screenplay 7200 firmware for it - they are the same projector but the inFocus firmware is more up to date than the Toshiba (will mean an infocus splash screen though).
     
  11. StuartBay

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    Thanks for the prompt reply. If I got the screenplay firmware upgrade, how would I apply it and what are the advantages.

    Thanks Stuart
     

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