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Thread: ST-225 speed up and down?

  1. #1
    Join Date
    Nov 2008
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    Default ST-225 speed up and down?

    I've had an old ST-225 drive that I've been using for a decade go bad. I could still get it to boot but after 15-30 minutes I hear the drive spin down then back up then down and stops at some point. I believe it might be a heat issue as after it cools down it will boot again.

    Any clue what to look at? Nothing looks bad visually, I'm thinking a power transistor???

    Thanks,

    framer

  2. #2

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    Very odd indeed. Possibly a cold solder joint?
    Compaq - “It simply works better”

  3. #3

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    I have drives that do that immediately, without any possibility of heat effects so it might not be heat related. FWIW, those drives are all useless.
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

  4. #4
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    First try it with a different power supply. It may be that your system's power supply is getting weak.

    If it still does that with a different power supply, then at least it is probably something on the logic board. It might be less complicated just to swap a board from a crashed similar revision ST-225.

    Sounds more like a bad solder joint to me. Any electrolytic capacitors would also be suspect these days.

  5. #5

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    There are a few electrolytics on the 225, but I think they are just filters. Don’t know for sure though. However, it couldn’t hurt to replace them at this point.
    Compaq - “It simply works better”

  6. #6
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    Very much sounds like a thermal issue around the motor driver, or the speed control circuit.
    If you remove the drive from the machine and keep a fan on it, does it take longer before failing?
    = Excellent space heater

  7. #7
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    Sounds as if the drive couldn't maintain the speed desired and so shut down. Dry-ish bearings, perhaps? Not unknown on ST-225s.

  8. #8

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    I think that's what's wrong with mine. They spin up to their max speed and then shut down, try to spin up, again, and shut down again.

    Other than bearings are there other places to look? FWIW, the drives I have that do this are not ST-225s.
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

  9. #9
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    Quote Originally Posted by Stone View Post
    Other than bearings are there other places to look? FWIW, the drives I have that do this are not ST-225s.
    If your power is good, and the bearings don't sound bad, I'd suspect something in the motor control circuitry, or the sensor that reads the index pulse. But when it has such control, a drive's microcontroller can shut down the motor for whatever reason it wants, which can also include problems moving or communicating with the drive heads.

  10. #10

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    Quote Originally Posted by SomeGuy View Post
    If your power is good, and the bearings don't sound bad, I'd suspect something in the motor control circuitry, or the sensor that reads the index pulse. But when it has such control, a drive's microcontroller can shut down the motor for whatever reason it wants, which can also include problems moving or communicating with the drive heads.
    In that case... I hope it's the bearings.
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

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