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Thread: Dec RK8E controller for RK05 wanted

  1. #21

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    As the original owner of this very drive : I also have one Plessey controller, which I need for my remaining 2 RK05's.
    My controller was bought in defective state, not yet got around to servicing it , and it totally escaped my mind that I need that 40 pin to DEC paddle cable/pcb. I don't have one.....

    Would it be an idea to make a single new board, which is both a terminator, and also contains standard IDC connectors for the drive-to drive and drive-to-controller ?
    That way we could use standard flatcable all around. On extra RK05's in the middle the terminator components would not be fitted.

    Second question : what does one replace the NiCad with ? In most cases these RK05 will only run for a few hours every year, so it never stays charged ...

    Jos

  2. #22

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    Hello Jos,

    Quote Originally Posted by jdreesen View Post
    it totally escaped my mind that I need that 40 pin to DEC paddle cable/pcb. I don't have one.....
    Would it be an idea to make a single new board, which is both a terminator, and also contains standard IDC connectors for the drive-to drive and drive-to-controller ?
    That way we could use standard flatcable all around. On extra RK05's in the middle the terminator components would not be fitted.
    I get your point, probably a smart idea. But Vince has already drawn the connector board.
    You can place two of these in a RK05 and use normal cables as well... (And probably remove the IC
    from those boards and make a shortcut for it?) So we only need the terminator then I guess?

    This is a terminator from Henk Gooyen, I will ask him if he can email sizes and pictures.
    m930-30.jpg

    Quote Originally Posted by jdreesen View Post
    Second question : what does one replace the NiCad with ? In most cases these
    RK05 will only run for a few hours every year, so it never stays charged...
    The modern equivalent is the NiMh battery which has less memory effect than NiCD. But still they will discharge.
    I have to check the circuit in the drive, because I wonder if there is always a current draw from the battery when powered down.
    If that is the case you should use an external charger to keep the battery alive...

    Does anyone have experience with this?

    Quote Originally Posted by jdreesen View Post
    I also have one Plessey controller, which I need for my remaining 2 RK05's.
    Jos, can you make a picture for me from the top-size of the top connector board?
    I don't have that board, but I think it is 1:1. Thanks!

    Regards, Roland
    Last edited by Roland Huisman; September 7th, 2018 at 12:12 AM.
    Wanted: case for Altair 8800 in good or bad shape or even a replica.

  3. #23

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    Quote Originally Posted by jdreesen View Post
    Second question : what does one replace the NiCad with ? In most cases these RK05 will only run for a few hours every year, so it never stays charged ...

    Jos
    I have been running RK05s for years without the batteries. I have replacement batteries, but have never installed them.

    As long as the AC power to the drive is not turned off before the heads are unloaded it should be OK without the batteries.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  4. #24

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    I have a powerful UPS unit that can handle the load and I use that

  5. #25
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    I used a battery pack from a wireless telephone and added quick-connect terminals while I was doing the replacement. Be sure to note that the original battery pack was wired contrary to standard color codes - white/red lead goes to negative end of the pack and the black lead comes from the positive end.

    http://www.computerarium.org/doku/do...05j_-_02-23337

  6. #26

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    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  7. #27

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    Thanks for the info on the batteries. I think I will place a battery just outside the
    RK05 with a small plug. Batteries in equipment are often troublemakers over time...
    I know we don't have much power failures. But you never know. If a small battery
    can prevent damage I will make use of it...

    Now a thing which is a bit confusing for me... The M993 cable interface board.
    There seem to be a few versions of it. With and without an IC and a pin-swap.

    The pin swap is from AU1 to AU2 on these two boards.
    Both of these go to pin 1 of the ribbon cable. What is the reason for this?

    rear m993a.jpg rear m993b.jpg
    (Pictures from: http://www.pdp8.net )

    I don't see this pin-swap in the schematics. Maybe I have don't have the right schematics.

    M993A.jpgM993B.jpg

    And if I look in the RK05 manual, these lines don't seem to have a function name
    on it, so probably not in use? Or is there an revision difference in controllers or RK05 drives?

    RK05 pinout.jpg

    Probably not a big deal, I even can make a jumper on the board.
    But I would like to know why...

    Edit: In the meanwhile I've opened the drive to check, both AU1 to AU2 are not in use.
    So DEC made a design change in an interface board for no reason? I can't imagine that...?
    Maybe there was a design change in later drives? Otherwise it would be very strange...

    Regards, Roland
    Last edited by Roland Huisman; September 9th, 2018 at 07:19 AM.
    Wanted: case for Altair 8800 in good or bad shape or even a replica.

  8. #28

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    In the meanwhile I've made a redesign of the M993 in Kicad.
    So now I will order this board in China. The AU1 to AU2 lines
    are selectable for whatever is was meant to be...
    And the driver circuit can be bypassed as well.

    layout.jpg

    If it works the drawings are free for who ever wants them... Just like the H851.

    Regards, Roland
    Wanted: case for Altair 8800 in good or bad shape or even a replica.

  9. #29

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    Will you make any extra boards?

  10. #30

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    Well I've ordered 5 of them and I don't need them all. One of them goes to
    Jos (if he wants) and one is for myself. That makes three spares for other collectors...
    Wanted: case for Altair 8800 in good or bad shape or even a replica.

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