Digital Projector Owners Inspect Your Machines Periodically

Discussion in 'Displays' started by Guy Kuo, Mar 29, 2004.

  1. Guy Kuo

    Guy Kuo Supporting Actor

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    It has come to my attention that some digital projectors (this includes both DLP and LCD) are prone to developing some problem that gradually worsen and may not be noticed. The changes are slow enough that you might not notice that 30 to 40% of light output is lost despite the bulb continuing to work.

    1. The reflector portion of you lamp houseing may deteriorate faster than the bulb itself. The reflector is the parabolic, aluminized mirror that concentrates the light of the bulb. It looks much like the reflector in a flashlight. While some gradual oxidation and darkening is expected during the lifetime of a bulb, some reflectors are developing many fine cracks (crazing) as early as 200 hours operation.

    2. DLP color wheels may become severly hazy. You can usually see the color wheel by simply pulling the lamp out of the projector and shining a flashlight into the bulb chamber. The color wheel should looke like shiney, color glass. If its surface is hazy or foggy, a large portion of light from the bulb simply gets reflected back to the lamp. As much as 30% of total light output can be lost if the color wheels become heavily contaminated. The contamination appears to gradually worsen on those machines which are prone to the problem. It can become so bad that one cannot see through the color wheel.


    I think it prudent for all digital projection owners to periodically pull their lamps and inspect them for reflector deterioration (and color wheel contamination if your machine is a DLP). Every 200 to 300 hours is a reasonable interval. Take care while doing the inspection because damage caused by you is your own responsibility. At the very least, inspect before your lamp warranty period expires. Always allow the projector to cool prior to pulling the lamp assembly. Instructions for pulling the lamp should be in your manual where it describes user lamp replacement procedure. Do NOT touch any lamp or projector glass surfaces. Do not attempt to clean the color wheel or lamp housing yourself unless you are willing to assume the risk of damage. Some less understanding manufacturers may even void your entire warranty if you perform your own cleaning. Call the manufacturer service department and ask for warranty service of affected machines.
     
  2. Neil Joseph

    Neil Joseph Lead Actor

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    Thanks for the heads up. I have checked my unit several times in the past and saw no reflector degradation on the lamp asm. Regarding the cleaning of dlp colour wheels, I second not cleaning by oneself.
     
  3. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    Thanks for that Guy. Valuable information. Now would you have any information about LCD blue polarizer filter degradation?

    Regards
     
  4. Guy Kuo

    Guy Kuo Supporting Actor

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    Sorry, I don't have info about the polarizer failures.

    Here is an image of a partially cleaned color wheel.

    [​IMG]


    Image of reflector crazing (many fine cracks)

    [​IMG]
     
  5. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    That is a pretty scary image of the colour wheel. Hard to believe that the light output drop would only be 30% with something that looked like that ...

    Kinda what my bathroom sink looks like after 4 months of no cleaning ... [​IMG]

    Thanks again.

    Regards
     
  6. Neil Joseph

    Neil Joseph Lead Actor

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    Damn that is scary. I wonder what the manufacturers have to say about this.
     
  7. Gabriel_Lam

    Gabriel_Lam Screenwriter

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    Suggestions on LCOS/DILA?
     
  8. ChrisWiggles

    ChrisWiggles Producer

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    that second photograph is artistically interesting. New better use for cheesy digital projectors? [​IMG]
     
  9. Guy Kuo

    Guy Kuo Supporting Actor

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    The color wheel contamination problem is not limited to the NEC HT1000. The InFocus X1 and physically identical Screenplay 4800 are also similarly afflicted.
     
  10. Neil Joseph

    Neil Joseph Lead Actor

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    Regarding the lamp reflector's degradation, I suppose the lack of filter maintenance would only add to the problem, correct?
     
  11. Guy Kuo

    Guy Kuo Supporting Actor

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    Dirty air filters certainly won't help. The reflector has tough enough a time staying in one piece when airflow is normal.

    The main thing I'd like to get across is that the digital projectors are not set and forget machines. One should take some time to inspect and maintain them.
     
  12. Rik P

    Rik P Stunt Coordinator

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    The bulb on my L300 had more cracks on it at 250 hours than the picture above, of course this was past the 90 day warranty.

    At what point during the life span of the bulb should you expect the reflector to begain wearing (cracking).. if ever??

    Not sure if most manufacturs have an hours use warranty aswell as the standard 90 day?

    Thanks for the good heads-up info Guy.

    Rick
     
  13. Ralph B

    Ralph B Supporting Actor

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    wow, I have my first new DLP projector. hated worries of problematic dust and was a big problem, now this. oh great! [​IMG]


    I wonder why they give only 90days of warranty on lamp. considering alot of people dont use thiers daily its really a slap in the face. looks like DLP owners will be making purchases on lamps to increase lamp sales.

    good pics. I will look for it in the future. I always maintained filter cleaning on my LCD.
     
  14. JeffHayes

    JeffHayes Stunt Coordinator

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    Guy & Co.,

    Am I to understand that these issues specifically relate to front projectors, or should I be concerned about these issues as well with my Samsung HLN617W rear projection tv as well?

    Thanks,
    Jeff
     
  15. ChrisWiggles

    ChrisWiggles Producer

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    Jeff, google tells me that your TV is a DLP RPTV, right?

    If so, then certainly it could suffer the same problems. It is a digital projector in there just the same as a FP dlp.
     

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