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Thread: Ibm 5151 vertical sync issue?

  1. #1

    Default Ibm 5151 vertical sync issue?


    I have an issue with my ibm 5151. Every time, when I turn it on after a longer pause, the positioning of the displayed text is not stable. It looks like that the signal just runs around the vertical axis. If I wait for a few minutes, it will be stabilized and it works without any problem.

    I guess it might be an old capacitor somewhere. I did not found any clear problem inside the monitor. Does anybody have a solution for this? Maybe it is the fault of the graphic card?

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  2. #2
    Join Date
    May 2006
    Melbourne, Australia


    Welcome to these forums.

    It sounds like the symptom trigger is temperature.

    I think it more likely that the cause is in the 5151. On that basis, try adjusting the 5151's V-HOLD control to a setting where sychronisation is achieved when the 5151 is cold and warm.

  3. #3
    Join Date
    Apr 2015
    Austin, Texas


    If there are any potentiometers inside the monitor, I'd suggest blasting them with deoxit gold or equivalent electronic cleaning spray. The copper wipers inside potentiometers oxidize over time and make bad connections, which can be affected by just about anything.

    If you can disassemble the pots without damaging them, it'd be best to fill them with dielectric grease after cleaning them to avoid the issue happening again.

  4. #4


    Cool! Thanks for both of you!


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