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4795Model I running

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  • Mike Loewen
    Jan 12, 2007
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      If Evan can crow, so can I. :-)

      I managed to get my 16KB TRS-80 Model I, Level II running last night.
      I got to use a lot of my toys, including the scope, freq meter and DMM.
      The system had a sync problem, and I couldn't get a stable display.
      Turns out that there was a bad inverter in both the horizontal and
      vertical sync circuits. I replaced two 74C04 chips, and it's running
      perfectly.

      This particular unit was a pain to work on, because it has a 3rd party
      lower case mod installed, along with two other switches. The switches
      were all attached with wire-wrap wire, which breaks if you look at it
      sideways. I also had to temporarily remove the Level II ROM upgrade,
      which is fastened to the bottom of the main board with double sided tape,
      to replace one of the 74C04s. Yes, that was a factory mod.

      All it needs now is an expansion interface. Anyone have one to
      sell/trade?


      Mike Loewen mloewen@...
      Old Technology http://ripsaw.cac.psu.edu/~mloewen/Oldtech/
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