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Dell P991 Monitor Problem - seeking help

Discussion in 'Electronic Repair' started by Ger, Nov 8, 2004.

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  1. Ger

    Ger Guest

    Hi Group,
    My PC Monitor is a DELL Multiscan P991. About 2/3 years old. Just about
    useable in its present condition.
    It suffers from the following symptoms:

    1. Screen is overly bright even after using brightness controls. Contrast is
    2. Icons are just a bit fuzzy
    3. The 'flyback' lines are visible always

    I have some electronics experience so taking the back off the monitor is no
    big problem. I know about the hi voltages etc etc.
    I am hoping that the above symptoms will be instantly recognisable by an
    expert as either some internal adjustment I can make or some component
    starting to fail and needing replacement.
    Any comments or advice would be very welcome please.

  2. Jerry G.

    Jerry G. Guest

    This sounds like problems in the CRT bias circuits, or in the HV multiplier.
    The multiplier on most monitors is located on the side of the HV transformer

    You must first check the biases to the CRT, and verify if they are in specs.
    This may be difficult to determine without the service manual. The G2
    (screen bias) to the CRT, and also the high voltage are important to verify.
  3. he

    he Guest

  4. Andy Cuffe

    Andy Cuffe Guest

    Did you run the "color restore" function in the menu? It usually
    fixes this problem.
    Andy Cuffe
  5. BubbaJim

    BubbaJim Guest

    As long as the back is open (I presume it is) look toward the rear, left
    or right, for a large transformer with two adjustment screws on it facing
    the rear. USING A PLASTIC TIP, turn the LOWER (screen) adjustment CCW and
    the thin lines will hopefully disappear. The upper adjustment is for
    focus. Hope this takes care of your problem.
  6. Ger

    Ger Guest

    Folks, many thanks for all the advice - off now to see if I can fix the
    Will report back.
  7. Ger

    Ger Guest

    Andy Cuffe wins the biscuit - COLOUR RESTORE fixed the problem (after a
    WARM UP of about 35 minutes).
    But well worth the wait :)))

    Thanks again to everyone

  8. Andy Cuffe

    Andy Cuffe Guest

    This monitor has no screen adjustment pot. It can only be adjusted
    through the service software. Both controls on the flyback of this
    monitor are for focus.
    Andy Cuffe
  9. BubbaJim

    BubbaJim Guest

    Good call, Andy...If a day goes by and ya don't learn something, it's a bad
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