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Thread: Disk Drive 1541 - Red & Green LEDs stay on??

  1. #1

    Default Disk Drive 1541 - Red & Green LEDs stay on??

    I have retrieved my old 1541 disk drive and it won't power up correctly with my Commodore 64. On power up (in the correct sequence) both the Red and Green LEDs stay on. The Red does not turn off as the manual and YouTube show.

    I have disassembled it and cleaned the circuit board (top and bottom) and lubricated the drive mechanism, but still no luck. Short of testing chips (or something) is there any way to make this work??

  2. #2

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    Quote Originally Posted by AAGDOS View Post
    I have retrieved my old 1541 disk drive and it won't power up correctly with my Commodore 64. On power up (in the correct sequence) both the Red and Green LEDs stay on. The Red does not turn off as the manual and YouTube show.

    I have disassembled it and cleaned the circuit board (top and bottom) and lubricated the drive mechanism, but still no luck. Short of testing chips (or something) is there any way to make this work??
    You have to start testing signals and chips. That behaviour means there's no correct code execution from the CPU. It might be lack of reset signal (PIN 40), lack of clock (PIN 30), almost anything on the RAM/ROM data paths, address paths
    a stuck IRQ and so on.
    If it has a socketed ROM, try removing it, lightly cleaning the pins and reinserting it.
    There's not much else you can do withouth at least a logic probe I'm afraid.
    Frank IZ8DWF

  3. #3

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    In most cases it is the 7406 in the top left corner near the IEC connectors. Second candidate the 74LS14 that is there as well. Third candidate: the ROM near the heat sink, top-right.
    The above is according my own experiences when repairing these drives.

    Good luck!
    With kind regards / met vriendelijke groet, Ruud Baltissen

    www.baltissen.org

  4. #4

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    Quote Originally Posted by Ruud View Post
    In most cases it is the 7406 in the top left corner near the IEC connectors. Second candidate the 74LS14 that is there as well. Third candidate: the ROM near the heat sink, top-right.
    The above is according my own experiences when repairing these drives.

    Good luck!
    Ok, my statistic on the "two leds and spinning forever 1541" (some of them have recently been documented with youtube videos):
    7406 on the reset path found defective: 1 time
    Bad seated ROM, bad socket: 3 times
    Bad 6502: 1 time (ok, it was a 1571, but still could apply to a 1541)

    I have a few more drives in the queue for repair, maybe I'll update the stats

    Frank IZ8DWF

  5. #5

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    Thanks to all who replied to me. I guess a logic probe is the next step which I can pursue after Christmas. I had hoped there would be a simpler explanation and/or solution. I am also renovating a 1541-II drive, but that seems to need only the latch/lever in front which I have found on eBay from Germany.

  6. #6
    Join Date
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    Quote Originally Posted by Ruud View Post
    In most cases it is the 7406 in the top left corner near the IEC connectors. Second candidate the 74LS14 that is there as well. Third candidate: the ROM near the heat sink, top-right.
    The above is according my own experiences when repairing these drives.

    Good luck!
    I agree, its most likely logic IC's

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