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Thread: First Apple 2e in 20 years! Vertical bars on boot

  1. #31
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    I didn’t have replacements, but I tried equivalent 74LS’s in their place, it acted the same. Would they have not worked for testing purposes?
    Bobby.

  2. #32
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    Update, the actual LED was bad. Replaced it and it lights up!

    I’ve noticed the garbage changes around on screen the same even when the CPU is removed or changed... so no, i don’t believe anything is really happening.

    12v is present on the expansion ports

    Any other ideas?

    Thanks heaps for the help so far!
    Bobby.

  3. #33
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    What else is 12V powered in a //e? Whatever it is, is likely fried, too. If the clock genny is fried, there's your problem...

  4. #34
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    My logic probe sees a pulse on pin 3 of the cpu, where the clock goes in... could it still be bad?
    Bobby.

  5. #35

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    Beware using logic probes on the clock input to the CPU. Depending on the probe it may not be able to handle a 1MHz signal. I chased my tail for a while thinking the internal clock generator was fried; but it was just my cheap logic probe not being able to see 'fast' pulses.

    That being said if your seeing a pulse on the input it's probably ok.... although without a scope it's difficult to tell if it's clean or not.

    Try your logic probe on the one of the address lines on a 4164. It will be interesting to see if it's accessing/refreshing the RAM.
    System 80 Expansion Interface located! Thanks to all who helped out and the good people in the NZ vintage computer forums!

  6. #36
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    Yes, there is a pulse on all address lines, as well as RAS and CAS.

    I've got another (non-working) board on it's way to me, hopefully I can make one good out of two!
    Bobby.

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