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Thread: PDP-8/M restoration - Jerry Walker

  1. #1
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    Default PDP-8/M restoration - Jerry Walker

    Jerry has started a very nice series on restoring an 8/M. So far, a detailed power supply repair and timing card testing. Thorough and well done with clear description of the logic used in testing.

    View on YouTube: https://youtu.be/WQyaQorPxc0

  2. #2

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    Quote Originally Posted by jackrubin View Post
    Jerry has started a very nice series on restoring an 8/M. So far, a detailed power supply repair and timing card testing. Thorough and well done with clear description of the logic used in testing.

    View on YouTube: https://youtu.be/WQyaQorPxc0
    I'm watching the first one, and it's nicely done so far.

    One thing that seems odd to me is that it looks like the CPU and memory were inserted backward when he got the machine?? It looks wrong in the video, and he hasn't commented on it. Probably just as well he inspected it before powering it up!

    Vince

  3. #3
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    It's picked up in one of the user comments below. He's very methodical and plodding in a good way.

  4. #4

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    Very nice. I noticed the backward cards too. Glad he did also.
    Last edited by tradde; January 22nd, 2021 at 03:13 PM. Reason: Added extra comment.

  5. #5
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    The order of the cards actually don't matter at all. DEC documentation have an order given, but putting them in backwards, or placing them elsewhere on the Omnibus works equally well.

  6. #6

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    Quote Originally Posted by jackrubin View Post
    It's picked up in one of the user comments below. He's very methodical and plodding in a good way.
    I coudn't see the comments, as they seem to have moved them to the very bottom, and I have to try to scroll past the bottom of the page; then they suddenly appear.

    I don't know who designs websites these days, but I they just get less and less intuitive.

    Vince

  7. #7

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    Quote Originally Posted by bqt View Post
    The order of the cards actually don't matter at all. DEC documentation have an order given, but putting them in backwards, or placing them elsewhere on the Omnibus works equally well.
    I'll agree about the order, mostly. But you do *not* want to insert cards with the component side facing the rear.

    Vince

  8. #8
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    Thanks Jack for pointing this out. I've watched the first two so far.
    Doug Ingraham
    2nd owner of Straight 8 SN1173
    5 other PDP-8's including an 8/i and a DECSet 8000
    SOL-20

  9. #9
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    Quote Originally Posted by vrs42 View Post
    I'll agree about the order, mostly. But you do *not* want to insert cards with the component side facing the rear.

    Vince
    Uh... Say what? I didn't look at the videos, but that would indeed be very bad. But it also sortof don't work so well. The flip chip connectors don't fit properly if you insert things the wrong way.
    But, well... People managed to push multiple 3.5" floppies into the drive at the same time, so I shouldn't assume anything.

  10. #10
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    My approach to restoring the machines at the RICM is very much like his. We document every step in a text only restoration blog that we put on the WWW page for each machine. This has been very helpful if a past problem shows up again. It has also been helpful for others that are restoring the same machine and want to know how to approach the restoration.

    His lengthy videos are much more compelling than our text blogs, and show a lot about how to use the test equipment, not just fix the machine. We need to add some lengthy videos explaining what we have done during a restoration, or how the machine works, instead of just a few seconds of video showing a machine running diags. The PDP-9 will likely be the first one that we document with lengthy videos.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

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