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Computer screen garbling text

  1. Dec 4, 2018 #1

    anorlunda

    Staff: Mentor

    My HP laptop screen is intermittently misbehaving 3 or 4 times per day. See an example below. But if I scroll that text off screen, then scroll back again, it renders correctly.

    upload_2018-12-4_16-20-48.png


    I'm wondering if it just might be a faulty connection.
    Should I try to unplug/plug the cables to the screen?
    Should I try to re-seat the memory chips?
    What other DIY remedies might I try?
     
  2. jcsd
  3. Dec 4, 2018 #2

    jedishrfu

    Staff: Mentor

  4. Dec 9, 2018 at 5:14 AM #3

    Svein

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    Then the graphic card drivers are OK. To me it looks like a video RAM problem - which again means the graphic card subsystem.
     
  5. Dec 9, 2018 at 6:05 PM #4

    FactChecker

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    I disagree with the font data problem theory. Characters appear good some places and bad other places. Reseat the easiest connections first. Reseat everything before you consider other hardware problems.
     
  6. Dec 9, 2018 at 6:16 PM #5

    jedishrfu

    Staff: Mentor

    Yeah I noticed that as I looked at it again today and started thinking maybe it’s an issue of graphics updates to the screen as the mouse pointer moves across it.

    I couldn’t find a good reference that described the problem though.
     
  7. Dec 9, 2018 at 6:26 PM #6

    FactChecker

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    If you can connect another monitor through HDMI or other, try that. It may narrow down the possible source of the problem.
     
  8. Dec 9, 2018 at 9:42 PM #7

    DaveC426913

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    No, not the font data. If that were the problem, we would see consistent corruption: all L's should have the same corruption everywhere in the text (see below). Same with all T's, etc.

    (Though, oddly, there is consistency with double letters, such as dropped, really, and !!)

    It does seem to be related to character rendering to-screen. As if, for every character sequentially printed to the screen, a random number of raster lines just doesn't light up.

    Notice that its always a line of pixels missing from a character - never individual pixels.

    screen.png
     
    Last edited: Dec 9, 2018 at 10:34 PM
  9. Dec 9, 2018 at 11:58 PM #8

    Tom.G

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    That sure points to contents of the Video Ram. Could be either reading the Character Generator or writing the VIdeo Ram. My first step would be clean all the dust out of the thing, memories don't like hi temps (all they have to sweat is bits, and that's what gets dropped). Hi temps can also disrupt the timing of the interface chips, giving identical visual effects.

    Then you can move on to wiggling everything in a socket or connector. Tthough it's probably best to keep clear of the CPU other than dusting it off.

    Please keep us updated, if it is working well enough to do so.

    Cheers,
    Tom
     
  10. Dec 10, 2018 at 10:53 AM #9

    DaveC426913

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    That's a very good point!

    What if Anorlunda's computer is corrupting the characters it sends to us here? Would we ever know?

    What if he's lying there on the floor right now trying to type "Help! I tried to use a metal featherduster to clean the motherboard and now I'm being electrocuted to death!' but all we're seeing is 'What other DIY remedies might I try?'
     
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