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Dirty tube?

Discussion in 'Projectors, Screens & Video Processors' started by cj, Jun 2, 2003.

  1. cj

    cj
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    I've just noticed what I thought was a dirty mark on my screen, but on further examination the mark is actually coming from my BD808S. What do I need to do to get rid of it?

    Thanks,

    Colin
     
  2. nathan_silly

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    Could be crap between the lens and crt's. Look into each lens whilst the PJ is on (reduce contrast & brightness so it doesn't hurt your eyes) and see if there's any grit, dust etc.

    When I took my RP apart these was some wood chippings between the lens and CRT's.
     
  3. cj

    cj
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    Yeah there's definitely some crap in there on the blue tube. Is this a simple operation to remove and clean it?
     
  4. nathan_silly

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    I'm afraid not. I'll take the Barco off your hands...:laugh:



    Remove the lens (normally 4 screws that attach the whole lens to the chassis) and blast the back of the lens, and the crt face with a air can. Put back on, job done.:smashin:

    Oh there might be grease smudges on the back on the lens (maybe from manufacturing), requires careful cleaning. Not sure what solution should be used (always a soft, clean lint-free cloth though)
     
  5. GagHalfrunt

    GagHalfrunt
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    I used the formula on Gordon Fraser's website to clean my lenses and it did a brilliant job. I can't remember the address though.

    I think it was isoprypl alchohol (99% pure), distilled water and a tiny drop of washing up liquid. Use a camera lense cleaning cloth from somewhere like Jessops.

    Make sure there's no grit on it first otherwise you'll scratch your lenses.
     
  6. Roland @ B4

    Roland @ B4
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    Phosphor is coated on the inside of a 4mm thick sheet of glass then there is a cooling liquid 7-10mm then another sheet of glass. this is only real area that is in focus.

    There is about 30mm of air before the first lens anthing on the lens will not show on screen. Rotate the back focus knob if your stuff moves its on the lens and will be too far out of focus to show on screen. Stuff on the lens reduce the contast a tiny bit but otherwise are unlikely to need cleaning out.


    If this blob has a sharp edge its a fault in the phosphor (if its sharp and in the middle sounds like the spot supression has gone and time to get your projector looked at)
     
  7. cj

    cj
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    Do you mean a sharp edge on the screen?
     
  8. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    He means if the mark onthe screen is sharp at edges it is a phospor defect. If it is a sharp dot with an out of focus glow around it the spot suppression is gone.

    I suspect it is a phosphor defect.

    Gordon
     
  9. Roland @ B4

    Roland @ B4
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    warn you now CRT owners dont look for these, once you see it you eye will go to that spot..................

    Unfortunatly there is no perfect medium for this projector lark, LCDand DLP get mafunctioning pixels Open/closed or juist plain stuck. CRT can get holes (air bubles or blobs where the phosphor is thicker or thinner than the rest. All CRT surfaces have them just a case of looking. they will on the whole be much smaller than the lamped equivalant.
     
  10. cj

    cj
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    Hmmmm I'll check again later, but I'm fairly sure it's an "out-of-focus-all-over" blob. In fact it looks like a very small curled up tequila worm :) I can only see it when there is a bright single coloured light background.
     
  11. Roland @ B4

    Roland @ B4
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    Chroma bug has mutated!
     

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