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Thread: TRS-80 Model 1 Keyboard

  1. #1

    Default TRS-80 Model 1 Keyboard

    Can you debug a CPU board without the keyboard attached ?

    My keyboard cable is poorly oxidized and is de-laminating.

    Has anyone tried to upgrade this ?

    I was thinking you could replace it with
    a ribbon cable and a IDC connector on the PCB(s).

    Ribbon cable has a small AWG, is it enough to
    make a sufficient connection ?


    Todd

  2. #2

    Default

    Mav, in Australia has replaced the ribbon cable with an IDE one. He wrote an article in TRS8BIT on how to do it. It's available as a free download at trs-80.org.uk

  3. #3

    Default

    I converted my kybrd connector to IDE.

    I'll post pic's when I'm finished.

    Can anyone confirm if the TRS-80 Model 1 CPU
    will boot normally with the keyboard disconnected ?

    It's a PIA to work on the PCB with the keyboard
    tethered to the CPU board.

    Todd

  4. #4
    Join Date
    Sep 2011
    Location
    Melbourne, Australia
    Posts
    746

    Default

    Thanks for the mention Dusty. Yes, I am Mav.

    Todd, if the computer is working properly you can power it up with the keyboard disconnected and it will display MEMORY SIZE? then some numbers which quickly scroll off the screen. When I'm repairing a M1 thats what I look for, then I proceed to attach the keyboard via an IDE cable and strip header.

    Hope this helps.

    Ian.

  5. #5

    Default

    Here's a few pic's of my conversion.

    4.jpg3.jpg2.jpg1.jpg



    Two keys don't respond, one will, if you tap it hard (sometimes get multiples)
    and the other (break) does not. B4 I tear into the actual switch(s), any pointers
    first so I don't destroy anything ?

  6. #6
    Join Date
    Sep 2011
    Location
    Melbourne, Australia
    Posts
    746

    Default

    Those keyboards on the orangy-browny PCBs suffer from dry solder connections, have a look under your break key where it solders to the board. That's nearly always the reason for non-responsive keys on this type of keyboard.

    Cheers,

    ian.

  7. #7

    Default

    Yep,

    A few cold solder joint's touched up
    and as good as new !

    Thanks !

  8. #8
    Join Date
    Sep 2011
    Location
    Melbourne, Australia
    Posts
    746

    Default

    Wow two out of two correct guesses! All of this stuff gets checked over on the refurbished Model 1s I sell, if people are wondering why I ask so much for them...

    I.

  9. #9

    Default

    I'm familiar with cold solder joints, I see them allot when
    I work on 80's pins & vids. Normally it's due to over stressed
    connectors.

    It never occurred to me...

    But now that you mentioned it, the keys do
    take a bit of pounding. I'll watch for it on
    the next one I work on.

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