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Video Projector Bulb

Discussion in 'Electronic Repair' started by Slim, Jan 8, 2007.

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  1. Slim

    Slim Guest

    I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
    light. How do I test the bulb? An ohmeter across the leads reads
    infinity. Is this normal?
    Thanks.
    Slim
     

  2. It is open (burned out).
     
  3. The lamp is high intensity discharge device and should normally read an open
    circuit. You can check the lamp only on a known working ballast. Does the
    projector have any diagnositcs? Most have an indicator to show when the
    lamp fails.

    Leonard
     
  4. James Sweet

    James Sweet Guest


    Depends on the bulb. If this is a discharge lamp as modern projectors
    use then yes, it will read open circuit until you get a few thousand
    volts to ionize the gas. If it's a very old projector with a tungsten
    lamp then it should read close to zero ohms cold.
     
  5. Are you sure? It seems to be a halogen or metal halide type.
     
  6. Also note that for a halogen or HID lamp, if you touched the glass with
    your fingers, it must be cleaned with alcohol or acetone before powering
    it. Finger oils absorb UV and etch glass. It will explode in short order.

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  7. James Sweet

    James Sweet Guest


    Metal halide = HID = high intensity discharge, this is *not* the same as
    tungsten halogen which is just a fancy incandescent lamp. Two completely
    different principals of operation. They both are made of quartz and
    contain halide salts as part of the gas fill but that's where the
    similarities end.
     
  8. Thanks for the info. Still learning!
     
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