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Yellow circle at centre of image

Discussion in 'Projectors, Screens & Video Processors' started by kjd, Sep 21, 2005.

  1. kjd

    kjd
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    Hi folks, this is my first time posting a thread. I have a Sanyo PLC SU30 which I bought off e-bay. The seller said it had a stain on the image, illustrated with a photograph, which I thought looked like a speck of dust. After several attempts at blowing the LCD's clean, and trawling through various forums , I have come to the conclusion that it's probably heat damage. The blemish is more noticeable on dark pictures. It looks like a yellow tinted circle with a surrounding blue halo effect, bang in the centre, about a 10th of the size of the image. There is also a blue blemish on the bottom of the image, more noticeable when I set the projector to 16:9 aspect ratio. Can anyone out there suggest what part of the imaging system may be responsible for this, and any ideas as how to test these theories.
    Thanks
    :lease: Keith
     
  2. Gazz

    Gazz
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    Morning Keith,
    sounds like the same problem I've got (see thread "dust blobs on Panasonic PT-LC 75E "). From what I can gather from the knowledgeable people on the forum, it appears to be the polariser (or polarizer, depending on your spelling preference) plate in front of the blue LCD panel which becomes discoloured due to high temps over a period of time.
    It seems the only choice is to replace the polariser. I can't find anyone to supply the part itself for my Panny but I don't know if Sanyo parts are more readily available.
    As for the blue blemish, I have one at the side of my image as well. Nobody's come up with an explanation yet but I have a theory.
    It could be that the light which can't get through the burnt patch (causing the yellow stain) is being reflected back off it at a slight angle then back out again through an unburnt part of the blue polariser, through the lens and onto the screen as a blue blob (in which case replacing the polariser would cure that as well).

    Like I say, that's just a guess (can anyone out there more tecky than me tell me if that's inspired thinking or the dribblings of a madman?)

    Also, Keith, for both thee and me - are there any members who can recommend a good service/repair centre who can take care of such things or supply the parts for brave/foolish people to try it?

    Thx
    Gazz
     
  3. kjd

    kjd
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    Thanks for the input Gazz. I have contacted a Sanyo parts dealer for the polarizer, and he's come back with a price of £102 for the part. So, even though it looks like it is the polarizer, I think I'll wait for a few more replies before I commit to buying the part. As to a good repair shop, considering the price of the part, plus the likely labour charge, I think I'll attempt the repair myself. I've been able to lay my hands on a service manual for the PJ which goes through every aspect of disassembly/ assembly.
     
  4. Gary Lightfoot

    Gary Lightfoot
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    I think the optical block assembly is quite critical in its alignment, so be careful that nothing moves out out of alignment, otherwise you could end up with the red green and blue edges to things where the individual RGB images no longer line up.

    If you have a go and do this yourself, please let us know how you get on, as it might be useful for others in the future if they have a similar problem.

    Gary.
     

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