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Thread: Screen Flicker on Compaq Contura 3/25

  1. #1

    Default Screen Flicker on Compaq Contura 3/25

    I've recently purchased a Compaq Contura 3/25 laptop. Once I had replaced the CMOS battery, entered the BIOS and saved the HDD geometry settings etc. it booted up and loaded DOS perfectly. Only issue is, after a couple of minutes from powering it on the screen starts to flicker.



    Any ideas what might be causing it to do this?

    I have 2 other Contura 3/25 that are 'spares and repairs' - 1 works perfectly but has a cracked screen and the 2nd has no display or backlight on the screen at all but if you connect an external monitor it boots up and loads DOS/Windows perfectly.

    I'd like to get as many of these 3 laptops up and running as possible so your help in working out what is causing the screen to flicker is greatly appreciated as if I can take any components from one of the other laptops and put them in this one to fix it then that would be great!
    My personal blog: www.retrocomputing.co.uk

  2. #2
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    1,593

    Default

    Something is awry with the backlight. Either the inverter is having problems, or the CCFL backlight tube is failing due to being worn out.

    Disassemble the screen to find the inverter board and replace the capacitors on it. If that doesn't solve the issue, try going up the chain and recap the motherboard. If that doesn't work, you may have to disassemble the LCD panel itself and either replace the CCFL or LED mod it with LED strip(s).

  3. #3

    Default

    Capacitors! There is an SMD capacitor on the inverter board that leaks and causes these issues. Clean the inverter, replace the cap, and I bet your backlight will return to normal.

    The Conturas are some of my favorites. They are lovely little machines.

    Also, the motherboard and DC/DC inverter need to be recapped as well, as both have electrolytic caps on them. The floppy drive has a couple too. Every damn one of them was leaking in my Contura 3/25. Thankfully, on the 4/25 and up, they stopped using electrolytic caps on the motherboard.
    Compaq - “It simply works better”

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