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Thread: Anyone have any documentation or knowledge on troubleshooting super serial II cards?

  1. #1
    Join Date
    Jan 2012
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    Connecticut, USA
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    Default Anyone have any documentation or knowledge on troubleshooting super serial II cards?

    So I have a stack of 25 super serial cards pulled years ago. They are in all sorts of condition, but no damage. I just hit a snag with 3 cards. I was trying to bootstrap an Apple IIe and using a known good IIe, known good cable, etc. all working from another apple II. The dip settings and modem/terminal jumper were correct. But on these cards I would get different results. Beeping and syntax errors as data came in, or system hangs.

    I cleaned the pins on all socketed IC's and used deoxit on the contacts.

    My next step would be desoldering and socketing the ttl logic and testing it. Are there any common points of failure? If I was to swap IC's with a known good card which, which order would be best?

    Id like to fix all the faulty ones if I can. I have the original book, but at first glance it doesn't have what I am looking for.

    Thanks,
    Mick

  2. #2

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    First thing to replace is the 6551. But why don't you sell the cards as faulty?

  3. #3

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    Write some test code and trouble shoot them. I always recommend using some version of Forth but each to their own. BASIC can also be used. Serial cards are relatively simple. Make a loop back connector. Here is a pdf of the specifications of the 6551.

    http://www.princeton.edu/~mae412/HAN.../6551_acia.pdf

    Dwight

  4. #4

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    Here is a schematic:

    https://www.apple.asimov.net/documen..._schematic.pdf

    A scope or even a logic probe would make easy diagnosis. The first thing to try is to write/read of the command register. That will quickly tell you if the bus interface is working and if the 6551 has a chance.
    Dwight

  5. #5
    Join Date
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    Default

    Thanks Guys I appreciate it. And I could use them, that's why I don't want to sell them as faulty. They go for $35 to $45 on avg

  6. #6
    Join Date
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    Since you chimed in both on the 6551, is this a common problem or IC that goes faulty often on these cards?

  7. #7

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    Quote Originally Posted by VERAULT View Post
    Since you chimed in both on the 6551, is this a common problem or IC that goes faulty often on these cards?
    On serial cards, in general the parts that fail most often are not the TTL, The 1488 and 1489 as well as the serial chips 6551. These cards also have firmware on them. That can go bad as well. I still recommend learning to diagnose the failures rather than part swapping. It will significantly improve your future experiences with other parts of the computers.
    Dwight

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