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Altair 8800 CPU Board Info

Discussion in 'Electronic Basics' started by logjam, Jan 20, 2006.

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  1. logjam

    logjam Guest

    I thought I would share some PCB scans and x-rays. Someone might be
    interested in them.

    If you are, save them now. They might not be on the internet FOREVER!

    A hint, schematics in manuals rarely matched the kit boards you
    purchased. In fact there was usually a cover page that listed changes
    to make to the board (component additions, jumper wire rerouting, etc)

    So board scans and x-rays ARE useful! ;) A really cool shot is the
    last one. It is the back board scan processed and then overlaied on
    top of the x-ray. Purple traces are on the top of the board, orange
    are on the bottom.

    I made these to duplicate the board. I will be tracing the artwork and
    making gerber files.

    One interesting thing, the SN74123N next to the crystal has a metal
    backing on the die and the SN7406N and SN7404N right next to it does

    Front Scan:

    Back Scan:

    X-Ray: (to scale)

    Hybrid X-Ray/Back Scan: (this allopws you to see the traces on the
    front and back at the same time without desoldering components)

    If you can do a better composite, go right ahead! and send me the
    results and instructions! :)

    Have fun!
  2. ironfly

    ironfly Guest

    Hey! These are great! Thanks..
  3. Now, THAT'S really cool!

    Dave :)
  4. And how did you make the X-ray?

  5. logjam

    logjam Guest

    I took the X-Ray using an EnvisionScan 18x18 digital detector. It has
    an 80 micron pixel pitch. I will be taking more x-rays of the boards
    and components. You guys interested in those shots too?

    I'm taking these to copy the boards, without risking damage. The 8080
    CPU on that card is considered rare. It still works too. I
    disassembled a 4k DRAM card from 75 and the legs were cracking off of
    all the memory ICs (it didn't work before either)

    I was using the large focal spot on the x-ray tube with a source to
    detector distance of 80" (to minimize any geometric distortion). The
    shot was made at 80kv 8ma. I would have used the small focal spot, but
    I really wanted to go home (less ma with the small spot, longer
    exposure needed)
  6. Guest

    Pretty determined I'd say. Are you planning on soldermask for your
    dupes? Please tell me you will be using flux remover.

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