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Thread: Sweet score for my collection

  1. #1
    Join Date
    Apr 2010
    Location
    Rimbey, Alberta, Canada
    Posts
    184

    Default Sweet score for my collection

    DSC_0417_sm.jpg

    I was working at a farmyard just down the road from home earlier this week, and spotted this little beauty sitting on a 'junk' pile out in the customers back yard. Literally just sitting there, out in the weather, up here in central Alberta. Upon spotting it the owner told me I could have it, as the whole pile is eventually destined for the scrapyard.

    I really wasn't expecting much, given it's poor storage conditions, but upon opening it up tonight I was pleasantly surprised with a layer of dust instead of mouse nests and horrible corrosion.

    DSC_0420_sm.jpg

    It's decent enough that if I didn't know better I might have plugged it in to see if it lives. Before that though I want to inspect it all more thoroughly, test the power supply, etc... Not to mention starting over researching what I'm even doing with it, I never thought I'd actually score an 8 like this so it's been a while since I've done any related reading...

    Card labels, front panel to back:
    Blank - wider card
    M8330
    M8310
    M8300
    M837
    M1703
    M1703
    M1703
    M1703
    M1705
    M1705
    M1705
    Blank - Orange handles
    M848
    M849
    G111 - 3 card set?
    M8320

    I also spotted a loose M8320 laying in the grass, which I grabbed. It's very dirty, but at least doesn't look all corroded.


    I'll have to go see this guy again, the 'scrap pile' where I found this 8/m is made up of a bunch of CDC cabinets populated to varying degrees , an old graphics terminal that I didn't take a good enough look at, and some tape / possible hard drives the size of washing machines. Regrettable we're having some early snow, so I'll have to wait for the weather to clear to see if I can get the rest of it from him.

  2. #2
    Join Date
    Oct 2008
    Location
    Kamloops, BC, Canada
    Posts
    5,860
    Blog Entries
    44

    Default

    Dammit, what are with all these old farmyard junk piles always cranking out PDP systems???
    = Excellent space heater

  3. #3

    Default

    Well, well, what a nice looking find.
    Can't have been lying out there too long.

  4. #4

    Default

    Wow! What a fantastic find!

  5. #5

    Default

    Excellent find!

    Doesn't look too bad from the pictures, but they're low res.

  6. #6

    Default

    That's pretty awesome. It's nice to see other vintage computer lovers in this neck of the woods too. My barn finds tend to be a lot less exciting.

  7. #7
    Join Date
    Jul 2014
    Location
    Rhode Island
    Posts
    1,238

    Default

    7x 12 bit GPIO boards?
    That is a lot of I/O.

    The power supply in that chassis won't work unless the output capacitors have more than 1000 uF of capacitance.
    It you just turn it on, it is unlikely to work.
    We have had good success with reforming the output capacitors for about a week.

    We made an LT-Spice simulation of the whole power supply so we could understand how it works.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  8. #8

    Default

    Quote Originally Posted by m_thompson View Post
    We made an LT-Spice simulation of the whole power supply so we could understand how it works.
    Cool! Would you mind sharing your simulation model? I have a PDP-8/M in my waiting-for-attention pile.

    I'm also trying to fix a switching power supply from my Tandy 6000 which is making power but not regulating. So far, I haven't managed to figure out what part of the regulation loop isn't doing what it's supposed to. I don't know why, but it hadn't occurred to me to try simulating the design to get a better understanding of it. It's a discrete implementation, so it may not be terribly hard to simulate in LT Spice. Thanks for the inspiration.

  9. #9

    Default

    What was something like that doing at a farm?
    I have dyslexia, I have alot of trouble putting my thoughts into words and spelling/grammar is something I struggle with.
    You may need to read my posts twice to understand what I said.

  10. #10
    Join Date
    Jul 2014
    Location
    Rhode Island
    Posts
    1,238

    Default

    Quote Originally Posted by NF6X View Post
    Cool! Would you mind sharing your simulation model? I have a PDP-8/M in my waiting-for-attention pile.
    I put the LT-Spice model of the H740 Power supply here.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

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