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Thread: Compaq Portable II - How to set Default Display??

  1. #1

    Default Compaq Portable II - How to set Default Display??

    My 1988 Compaq Portable III is in excellent shape, but on bringing it out of the storage this year, the "pop up" plasma display would not show anything. It appears to boot properly with the green indicator lights and "beeps" sounding correctly. I purchased a 9-15 pin adapter to attempt a display on another monitor ("default display"). But nothing shows there either. Any ideas??

  2. #2
    Join Date
    May 2006
    Melbourne, Australia


    For what it's worth, some Toshiba notebooks can have this symptom if the main battery is low. Example [here].

  3. #3


    Modem 7,

    Thank you for the reply. My Compaq Portable runs on normal AC power (house hold) so there is no battery to discharge. The possibility of loose connections to the display is a possibility too, and when I re-open it, Ill do some "pressing" and also check the jumpers to the default display (in case they weren't set back properly).

  4. #4
    Join Date
    Aug 2006
    Chicagoland, Illinois, USA
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    Quote Originally Posted by AAGDOS View Post
    I purchased a 9-15 pin adapter to attempt a display on another monitor ("default display"). But nothing shows there either. Any ideas??
    The 9-pin port marked "RGB" is not VGA, it's CGA. You'll need a CGA monitor, or some sort of converter from CGA to VGA.

    The appeal of that system is the built-in plasma display, so you should try to troubleshoot that. If you're not seeing anything on it, and are sure you have the contrast controls are set correctly, then you'll have to start troubleshooting the hardware. Barring that, you might be able to find another Portable III for cheap and swap the screen.
    Offering a bounty for:
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    - A working Sanyo MBC-775, Olivetti M24, or Logabax 1600
    - Documentation and original disks for: Panasonic Sr. Partner, Zenith Z-160 series
    - Music Construction Set, IBM Music Feature edition (has red sticker on front stating IBM Music Feature)

  5. #5


    Thank you for the information! I will look for either a CGA monitor or convertor. I can try a "minimal" check of the hardware, but only at the connector level. More than that will need other technical expertise...if I can find someone who has experience in fixing these. I am located in Central CT.

  6. #6
    Join Date
    Oct 2016
    Illinois, USA


    If the later models use the same key combos as the original, CTRL-ALT-< and CTRL-ALT-> may be of assistance. Those two combos can be used to alternate between MDA and CGA mode, allowing for 80 column text output on a external display.

  7. #7


    MrArgent, Thank you for the info. I did try CTRL-ALT-< but did not get any display. I will check the jumpers on the mother board. Something may have been changed, if I can't find a loose connection to the original display. Amazon had a $94 "box" that could convert the VGA signal to CGA, but I'd rather spend the money to have some expert track down the original problem. I am located in central CT.

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