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Re: [midatlanticretro] IMSAI 8080

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  • Mike Loewen
    ... The first items to check would be the 4 large electrolytic caps in the power supply. Many people recommend a re-forming operation before you hit them with
    Message 1 of 61 , Jan 29, 2013
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      On Tue, 29 Jan 2013, DanielB wrote:

      > I just managed to get my hands on an IMSAI 8080 that probably hasn't
      > been power up in decades. I am very interested in getting this thing up
      > and running again. I have a pretty good background in electronics and
      > electronic repair, but I am looking for any advice on power up something
      > like this for the first time. Any recommendations on what I should check
      > before attempting a power up? Any advice would be much appreciated.

      The first items to check would be the 4 large electrolytic caps in the
      power supply. Many people recommend a re-forming operation before you hit
      them with working voltage. Here are a couple of messages about it:

      http://www.vintagecomputer.net/browse_thread.cfm?id=237

      A constant current supply would make things easier. There are many who
      advise against using a Variac.

      Also, inspect any Tantalum caps on the S100 cards for burns and
      exploded caps. Likewise, check for bulging electrolytic caps. Make sure
      there is no hardware rattling around in the bottom of the case. Pull the
      S100 boards before you power it up for the first time, and check the PS
      voltages.


      Mike Loewen mloewen@...
      Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/
    • DanielB
      Yep, front panel is working good now. One odd thing I have run into is that from the Zapple monitor I can write to the SMB s onboard RAM, but I cannot write to
      Message 61 of 61 , May 14, 2013
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        Yep, front panel is working good now. One odd thing I have run into is that from the Zapple monitor I can write to the SMB's onboard RAM, but I cannot write to the RAM on the memory board but I can write to the memory board from the front panel.

        Dan

        --- In midatlanticretro@yahoogroups.com, joshbensadon <no_reply@...> wrote:
        >
        >
        >
        > --- In midatlanticretro@yahoogroups.com, "DanielB" <danlb_2000@> wrote:
        > >
        > > After bad chips I finally got the front panel working, and after a couple bad tantalum caps on the SMB I also got that working. Very exciting when I got the Zapple monitor prompt!
        > >
        > > https://lh6.googleusercontent.com/-uQShOzInDeE/UZFoWnYYpsI/AAAAAAAACII/80vupyb6Psc/w883-h662-no/IMG_3933.JPG
        > >
        >
        >
        > Daniel,
        >
        > That's looking great! Very well done :)
        >
        > Can you now Examine/Deposit via the front panel?
        >
        > :)J
        >
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