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Thread: No video on Otrona Attache

  1. #1

    Post No video on Otrona Attache

    Problem

    Upon turning on, the power supply signals the POK (Power OK) signal and attempts to power the computer, however
    when turned on the crt filament will light up for a second and then go dim. I first checked the CPU (Z80) and then
    checked the CRT driver (5027). I can't really test all that much because I've only got a multi-meter. The board does
    have the High res mod and another little square board, I attempted to power it up without these but that didn't make
    a difference. I hooked up a composite screen to the video out to test if it was just the monitor but again with no avail.

    Any help would really be appreciated.

  2. #2

    Default

    Quote Originally Posted by FishByte View Post
    Problem

    Upon turning on, the power supply signals the POK (Power OK) signal and attempts to power the computer, however
    when turned on the crt filament will light up for a second and then go dim. I first checked the CPU (Z80) and then
    checked the CRT driver (5027). I can't really test all that much because I've only got a multi-meter. The board does
    have the High res mod and another little square board, I attempted to power it up without these but that didn't make
    a difference. I hooked up a composite screen to the video out to test if it was just the monitor but again with no avail.

    Any help would really be appreciated.
    You are not likely to get far without a scope. ( don't buy a cheap 1MHz scope. it is not fast enough to deal with the video circuit ). There is a schematic on the web.
    Dwight

  3. #3
    Join Date
    Mar 2016
    Location
    Georgia, USA
    Posts
    641

    Default

    Quote Originally Posted by Dwight Elvey View Post
    You are not likely to get far without a scope. ( don't buy a cheap 1MHz scope. it is not fast enough to deal with the video circuit ). There is a schematic on the web.
    Dwight
    https://tinymicros.com/mediawiki/ima...Schematics.pdf

    That's a cool looking little machine. I hope you get it sorted out.

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