Apple II DuoDisk not getting power?

Discussion in 'Apple Collectors' started by cjbriare, May 4, 2012.

  1. cjbriare, May 4, 2012
    Last edited: May 5, 2012

    cjbriare macrumors member


    Nov 8, 2008
    Las Vegas, NV
    Im looking at this Apple IIe system to buy here in town.

    It's a really good buy, lots of accessories and software original boxes and manuals, etc.

    Problem is, I went there to test it tonight, and the duodisk was not getting power. I tried both ports on the computer, and it's an Apple DB-29 cable which had some pins missing.. (not sure if that makes a difference, it was only ~2 pins)

    So next thing i tried, the guy had an apple II 3.5" drive. I connected that to the machine, and the duodisk into the 3.5 drive just for testing. The red light stayed glowing on the drive, but no disk activity.

    Also, both red lights on the drive would come on for a split second whenever turning the machine on or off.

    My only conclusion is that it's either a bad cable or Duodisk card.

    Any ideas? I really dont want to miss out on this system for something little like this. :p
  2. MacTech68 macrumors 68020


    Mar 16, 2008
    Australia, Perth
    It's rather difficult to say what might be the fault. DuoDisk drives do have some TTL logic that can fail, but they are socketed ICs so replacing them is fairly easy. Determining which IC is faulty may be the problem. There is also a chance that the drive interface card is at fault.

    It could simply be that the interface card is not making reliable contact in the slot. Re-seating the card in another slot (slot 5 instead of the preferred 6) might help.

    The old DISKII drives used to be easy to blow up the 74LS125 by off-setting the pins of the drive's 20 pin cable on the interface card. It's also possible to do this on the DuoDisk by plugging and un-plugging it when the system is powered on.

    The DuoDisk's cable (P/N 590-0114) (DB25 (25Pin) to DB19 (19 Pin)) should be missing pins on the DB25 side. Specifically, Pins 1, 13, 22 & 25. All pins should be present on the DB19 side. Missing pins are marked in red in the attached picture.

    Attached Files:

  3. cjbriare thread starter macrumors member


    Nov 8, 2008
    Las Vegas, NV
    Sorry for not posting this earlier, but I did purchase the lot thinking i could get replacement parts later. Once i brought home the car load full of boxes, i took out all the cards except the duodisk and serial cards, hooked it up and the disk drive worked. Weird. o:

    Thanks for the help though. :)
  4. Lil Chillbil macrumors 65816

    Lil Chillbil

    Jan 30, 2012
    buy first ask question later


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