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Thread: Compaq Portable III Vertical Lines

  1. #1

    Default Compaq Portable III Vertical Lines

    I bought a Compaq Portable III last year that has vertical lines on the display (mostly bright lines to the right and one black in the middle). The lines have been quite an annoyance and will sometimes disappear and reappear at random (along with an occasional horizontal line (present even when text is not here)). Additionally, I found two caps on the screen PCB which have some corrosion on the leads. I believe that this is causing another problem, which is making seemingly random pixels and bright lines show up around text (only when text is displaying). I have already tried reseating the ribbon cable on both ends, which doesn’t change the situation. I have also tested an external monitor, and the lines are not present. I am thinking that this is the display, but I need your input on this.

    P.S I have looked on other forum posts asking this question, none of which provided a clear answer (if any at all). I request detailed instructions along with pictures/diagrams of what needs to be fixed. I will also post a time lapse of the issue and take pictures of the display’s pcb later. It would be really nice to get this neat machine fully working and pleasant to use. This display is too cool to throw away.

  2. #2
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    Typically static lines are an indication of a failure in the bonding of the cabling for the screen to the PCB with the grid drivers. Some people shim the ribbons a little and that helps but otherwise once they fail there's nothing that can be done to reattach them.
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  3. #3

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    Quote Originally Posted by NeXT View Post
    Typically static lines are an indication of a failure in the bonding of the cabling for the screen to the PCB with the grid drivers. Some people shim the ribbons a little and that helps but otherwise once they fail there's nothing that can be done to reattach them.
    Thank you for your quick response. I think I understand what to do now. One thing that I forgot to mention is that glue holding one of the ribbon cables down on the monitor has disbonded and now lets the ribbon cable raise a bit. I also remember possibly seeing corrosion on of of the driver chip legs.

    Another question, is it possible that a reflow of the ribbon cables with hot air or a soldering iron will fix the lines?

  4. #4
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    I can't say for certain it's ultrasonically welded but I do know that ribbon tech like this and with LCD's does not reattach with the pass of an iron or some hot air.
    = Excellent space heater

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