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25023RE: [midatlanticretro] FD 1771 - Floppy Drive Controller TAX?

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  • Bill Sudbrink
    Apr 3, 2012
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      Some things I would check:

      Make sure FD1771 pin 25 is truly grounded. It is
      socketed, right? Did you reseat the 1771?

      Likewise, make sure you have a good clock signal on
      1771 pin 24.

      What does the 74ls175 (u33) look like? Is it socketed
      or soldered? Are its pins tarnished? Does the clock
      on pin 4 of the 175 look good?

      Basically, if any of the chips on the board are TI,
      socketed and have pins tarnished to black or almost
      black, it would probably be a good idea to gently lift
      and reseat them.

      Are the gate voltages on the 74ls08 (u36) good? If they
      are marginal, you might be getting noise in the signal.

      Bill S.
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