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Thread: Olivetti M24 display

  1. #11
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    You are lucky, after googeling about Xerox 6067 and 6068 I can confirm that they are also just relabeled M24. So the Keyboard is not even only Ok, it's the most AT keyboard style closest keyboard for M24 I ever have seen.
    - https://books.google.de/books?id=pDw...206068&f=false
    - https://www.computerwoche.de/a/xerox...europa,1172090

  2. #12
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    Thank you for checking that. The system seems to be partly alive!

    I have soldered a VGA connector and rewired the DB25 to DB15 and connected it to a VGA monitor and now I get this:
    IMG_0023.jpg
    It stays there and does not go further.

    So it does seem that maybe there is a problem with my Olivetti display.

    However what should happen next? Should it boot from the HDD?

  3. #13
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    What does the keyboard do? Do you see the flickering LED?

  4. #14
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    Well I do not have the original Olivetti keyboard. The Xerox keyboard I have has only 2 LEDs: one for Caps Lock and one for Num Lock. They seem to be both lit all the time.

  5. #15
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    Hmmm, during the POST diagnostics, the LED on the regular M24 flickers, I guess to show that the keyboard is communicating.

    On the other hand, could it be that the display board really works, but your VGA monitor isn't adjusting to a change in sync frequencies? A scope on the H and V sync lines would show this.

  6. #16
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    I think display is is allmost Ok. It stops after checking first 128 kB.

    You should open the lower case where the mainboard is placed upside down in the bottom and see how much memory is installed. Only 128 kb or 640 kb (half of the memory sockets populated, or all?)

    Next step of M24 after checking memory is harddisk (option-rom at c800) and then floppy drive.

  7. #17
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    Quote Originally Posted by Chuck(G) View Post
    Hmmm, during the POST diagnostics, the LED on the regular M24 flickers, I guess to show that the keyboard is communicating.

    On the other hand, could it be that the display board really works, but your VGA monitor isn't adjusting to a change in sync frequencies? A scope on the H and V sync lines would show this.
    I already checked and posted that info a few posts above. I am seeing 60Hz on the Vsync pin and something similar on the Hsync, however there is a much higher frequency signal encoded over that one. That coupled with the fact that I got an image on my VGA monitor once, it means the display card is not entirely broken.

    However other things seem to be not alright. For example I cannot get the same image anymore on my VGA monitor again. And whether or not the CapsLock and NumLock LEDs are on depends on how many times I power cycle the computer.

    I tried re-sitting all the chips which are in sockets but that did not seem to make an impact. Something is definitely loose or a bad connection somewhere.

    I will try opening up the Olivetti display because that one should at least get power.

    Now if it behaves the same as as the IBM 5150 associated monitor that it does not display anything if it does not get any data (even though it has current) then it would explain the monitor behavior.

  8. #18
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    I concur that your display board is working, since you originally got that image on the VGA monitor. However, getting a different results every time you boot is troubling; I'd ensure the battery is off the motherboard as it may be leaking acid onto traces. Also replace any capacitors that look bad.
    Offering a bounty for:
    - The software "Overhead Express" (doesn't have to be original, can be a copy)
    - 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)

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