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Thread: Nightmare!!!!!!!!!

  1. #1
    Join Date
    Aug 2016
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    Default Nightmare!!!!!!!!!

    Hi to All,

    I have bough a Powerbook 180 with a supposed faulty trackball... that... is faulty.
    I have replaced it and now the Mac runs flawlessly BUT... after a while the screen started becoming dark on the corners! After a shut down it remains the same.
    Now I try to wait up to tomorrow but my fear is that, even if the screen recovers, it will get dark anyway again!
    DSC_0001.jpg
    The picture is good and reflects quite well the issue...

    Any ideas?

    Thank you

  2. #2

    Default

    Failing back light?
    Daniel P. Cayea - The Lyon Mountain Company - Plattsburgh, New York 12901
    Vintage Equipment: IBM 5150 * IBM 5161 * ThinkPad 770ED
    Modern Equipment: MacBook Pro 13 * Alienware M15R3

  3. #3
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    Default

    Quote Originally Posted by lyonadmiral View Post
    Failing back light?
    mmm... a old "lamp"? Do you know if there is a way to turn off completely the back light?

  4. #4
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    Default

    maybe the lamp behind the screen is old and need replacement.
    also check the voltages from the high voltage wiring that goes to the lamp.
    if they are low maybe you need to recap the board.

  5. #5
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    Default

    Quote Originally Posted by soviet9922 View Post
    maybe the lamp behind the screen is old and need replacement.
    also check the voltages from the high voltage wiring that goes to the lamp.
    if they are low maybe you need to recap the board.
    The lamp is not the issue... I have discovered there is a slider that control the light and the issue is there even at 0 back light!!!

  6. #6
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    Default

    That's just Tunnel Vision. It is suspected that the seal around the LCD glass is failing and moisture has started getting between the layers of glass. The result is as the screen gets used it gets a tunnel-like ring around it that goes away if powered off for a few hours but always comes back. You could try dismantling the LCD assembly and putting the raw assembly in a food dehydrator for a week and then resealing the edge but otherwise nobody knows how to fix it.
    = Excellent space heater

  7. #7
    Join Date
    Jan 2014
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    Default

    The issue is with deterioration of the LCD panel itself. This is common on that generation of Powerbook.

    Go to the forums on 68kmla.org and search for tunnel vision. I don't think there's a known good cure, but I haven't really researched it.

  8. #8
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    Default

    mmm... I do not correlate the issue to humidity! The humidity issue would have to be related to the area where it is located! And it's anyway a bit strange that it is always "so simmetrical"!!!
    Anyway i have tried the opposity putting the LCD... in the refrigerator!!! The "good" area become quite little BUT the "bad" area was not black! It was visible with REVERSED greys than the good one... and yes... there are light grey areas and black grey areas...
    I do not know how this could help but this is a thing that was never told (or at least I have not read it anywhere).
    Now I also want to try to turn off the monitor but keeping the PowerBook on (I do not know if this is really possible) to check if the monitor get back to "good" situation while only the monitor it's off... if it does the issue is really related to the monitor... if not it could be the electronic driver!
    I do not have many ideas but I want to check all possible simptoms hoping I can find out something that it's not yet known...

  9. #9
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    mmm... I do not correlate the issue to humidity! The humidity issue would have to be related to the area where it is located! And it's anyway a bit strange that it is always "so simmetrical"!!!
    I actually ran a joint experiment with The Hackery over seven years and we confirmed with altitude being a variable (100 and 1500 feet), an affected LCD stored in a 50-80% (nonoperating) relative humidity environment developed tunnel vision faster and worse than an LCD stored in a 20-40% (nonoperating).
    Those who saw my 180 at VCF:PNW saw my side of the experiment and a few noticed that even after six hours of continuous operation the screen was still perfectly useable.
    = Excellent space heater

  10. #10
    Join Date
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    Default

    Wonder what would happen if the LCD panel was placed in a vacuum chamber for awhile.

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