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Thread: Seagate ST-412 stuck (spindle not spinning)

  1. #1

    Default Seagate ST-412 stuck (spindle not spinning)

    Hi everyone,

    I'm a new guy on this forum, this is my first post, so be gentle, if I make rookie mistakes here .
    I joined the forum, because I've got a problem with Seagate st-412 hard drive, that I don't quite know what to do with.

    But first, a bit of it's history. I believe it was around 1995 or so, when I spotted IBM xt (5160) on a local computer
    shop in small town of Varkaus Finland (that's near my home town). I liked it immediately, because I thought I might
    get it cheap. Back in that day I believe I might have had 386 PC and I had no idea, what I had found or what I was
    dealing with. But, I wanted it and I think I must have stroke a deal for about 20 Finnish marks of that time - that's
    about 3-4 euros of today.

    I took it home and was a bit of dissappointed. I did not work and I had no idea what to do with it. It did get some
    text on the green monitor, but that was about it. Soon I got bored with it - these were not appreciated by anyone
    at that time (including me) and they were considered total junk. At least I did not junk it (but the next worst thing),
    I had decided to storage the unit in a cold storage. It gets easily -30 degrees celsius here during winters, which
    probably was not very good decision to think afterwards.

    But, what do I have here now:
    IBM PC/XT 5160, with one 360kb floppy and seagate st-412 HD.
    With green monitor, 512kb ram and keyboard.

    Somehow, I've gained the interest of this ancient unit now. I've rapaired
    maybe a couple of dozen commodores and 1541 drives, but this IBM seems to be a challenge.

    So, I connected the unit and powered it up. Just as I saw green monitor come alive and ram check
    started to count, I heard a loud BANG and strong gray smoke started to come from inside the main unit,
    with nasty electrical welding sounds. I then quickly pulled all the cables, took the unit to outside to cool
    off for a day . A couple of interference caps were blown and i replaced them and the power supply now works
    again.

    Then there were a number of error codes on the screen and the IBM did not boot, even to the basic.
    error codes, such as 301, 201, 1701 and 601 were displayed and ram test ended in 192kb.
    Whoa. What a bummer! But, one by one, I took/am taking this challenge to get it up and running!

    First thing I realized, was that the keyboard is missing one key (alt). It was the cause to get stuck in key test,
    and prevented even the boot to basic. I have now physically blocked that key from coming up (there is a spring
    showing in the missing key and pressing it down the error disappears) and the IBM now does boot to basic (rom) !
    Yes! One small step before the giant leap. . . Then I tested the ram chips and found out one busted ram in bank 3.
    Replaced with commodore 64 8kb ram chip and now I got full 512kb ram with the xt!

    When I got the hard drive hooked up, I got 601 error code during the boot check-up. I recon, it is error code for the
    360 floppy drive or its control card. I also got 1701 error for the HD. Both, the HD and the floppy were removed
    during my RAM checks. I reinserted the floppy control card and pulled all the cables and reinserted them in case
    there is corrosion or trouble with contacts. But all the contacts look like very good (especially considering that the unit
    has spent probably over 20 years in outside cold storage). i did not install the HD controller card yet, or the HD itself
    and made a boot test. I put C64 floppy inside the drive, since I have no pc floppies, just to see what happens during
    boot attemp. Turns out, no longer 601 error, the red led on the drive comes on, spindle spins for a very short time
    and then the pc gives up and boots to basic. But hey - I think there might now be a small chance to boot to dos,
    if I can manage to create pc bootable 360kb floppy!

    In the mean time of me figuring out how to make that bootable floppy, I'm asking for opinions on that stuck
    seagate st-412 hard drive. I tried it with a modern atx power supply, but nothing. Checked with multimeter, that
    the drive does receive both 12V and 5V, but it's spindle will not turn on. I'm pretty sure, that if the drive spindle would
    start spinning, there would be significant noise, but now it is very quiet. Therefore I guess it is stuck.

    --> hence the question, what is the best action from here on with that HD?

    I'm experienced with desoldering logic chips without destroying them in the process,
    but I would not go into that immediately. Maybe the spindle motor has met it's destiny
    after the unit has been out in the storage for so long. But, who knows, maybe that was the
    reason, the IBM was in that small computer shop in the first place back in the 90's.

    Well, this was quite a long story and first post - but I hope it was fun to read as it was and is fun for me
    to tinker with this old pc. Any comments or suggestions are welcome, silly or not

  2. #2
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    Quote Originally Posted by VintageVic View Post
    Hi everyone, ...
    Welcome to these forums.

    Quote Originally Posted by VintageVic View Post
    I'm pretty sure, that if the drive spindle would start spinning, there would be significant noise, ...
    Yes. The spindle noise of an ST-412 is very noticeable. And if you put your hand on the top of the drive, you can feel vibration.

    My ST-412's spindle turns when only power is applied to the ST-412 (no data nor control cable attached).

    Quote Originally Posted by VintageVic View Post
    --> hence the question, what is the best action from here on with that HD?
    1. See if the +5V and +12V is actually getting to the drive's PCB. I.e. Make the measurement on the PCB.

    2. If the PCB is removed, the spindle can be seen. Photo at [here]. Are you able to (slowly) turn the spindle by hand ?

  3. #3
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    Silly question, I know, but here goes: Have you checked that the spindle brake is functioning correctly? I've seen both Tandon and Seagate drives where the spindle brake has failed. The normal operation is that the brake is activated (brakes the spindle rotation) when power is removed. If the brake electronics fail or the brake itself develops a bad coil, you don't get much in the way of rotation.

    Usually, the simple way to handle this is to remove the bloody thing.

  4. #4

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    After 20 some years of continuous (cold) storage I would think stiction is a likely suspect.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

  5. #5

    Default

    Hi all,

    and thank you for your answers !

    >1. See if the +5V and +12V is actually getting to the drive's PCB. I.e. Make the measurement on the PCB.

    Yes, I did measure on the pcb. XT:s own power supply gives 4,96V on the 5V side, but I think it is ok.
    atx power gives 5,03V there, which at least is good. 12V side were similarly close to the specs.

    >2. If the PCB is removed, the spindle can be seen. Photo at [here]. Are you able to (slowly) turn the spindle by hand ?
    >Quick reply to this messageReply Reply With QuoteReply With Quote Multi-Quote This Message

    Thanks for this and the pic ! I have not yet removed the pcb, but will plan to do just that tonight.

    And thanks to Chuck for the comment on the brake! Wow - had no idea they had made brake to there.
    I read from somewhere, that you could damage the drive, if you spinned the disk by hand the wrong way.
    Probably that was related to the brake ? But it's very good to know, that the brake actually exist and that
    it can be removed. I'm eager to check this tonight. After I find a strong screwdriver. I did try to open the screws
    with a small one last night, but they were really tight.

  6. #6

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    Quote Originally Posted by Chuck(G) View Post
    Silly question, I know, but here goes: Have you checked that the spindle brake is functioning correctly? I've seen both Tandon and Seagate drives where the spindle brake has failed. The normal operation is that the brake is activated (brakes the spindle rotation) when power is removed. If the brake electronics fail or the brake itself develops a bad coil, you don't get much in the way of rotation.

    Usually, the simple way to handle this is to remove the bloody thing.
    You are correct. I removed the pcb, but spindle is not moving - much. Just very slightly to each
    direction. But... how to remove the brake ? Is it that thingy, which is touching in the center of the
    spindle ?

  7. #7
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    Quote Originally Posted by VintageVic View Post
    And thanks to Chuck for the comment on the brake! Wow - had no idea they had made brake to there.
    My ST-412 does not have a spindle brake.
    On your ST-412, do you see anything extra (mechanical that is) to what is shown in the photo at [here] ?

    Quote Originally Posted by VintageVic View Post
    I read from somewhere, that you could damage the drive, if you spinned the disk by hand the wrong way.
    I do not know why that would be so.

    On my ST-412, as viewed from underneath the drive, the drive spins the spindle clockwise.

    If you can manually spin (slowly) the spindle, that rules out head/s stuck to platter/s, and certain other possible causes.

  8. #8

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    >My ST-412 does not have a spindle brake.
    >On your ST-412, do you see anything extra (mechanical that is) to what is shown in the photo at

    oh. I will try to post a pic here (if i'm allowed to do so).
    I do not see any external brakes there, that I could remove.


    >On my ST-412, as viewed from underneath the drive, the drive spins the spindle clockwise.
    >
    >If you can manually spin (slowly) the spindle, that rules out head/s stuck to platter/s, and certain other possible causes.

    This one is indeed stuck. It will turn maybe about 5mm to each direction, then there is resistance
    significant enough to discourage me to push harder.


    st-412.jpg

  9. #9
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    Probably not the best way, but I have gotten old seagate drives to spin again after repeatedly connecting and disconnecting the power, usually takes around 4 or 5 times. Though in these cases I was reasonably sure that the issue was stiction and once the drive was running again I let it run for while to heat up the grease and re-distribute it.

    That said, I would recommend you replace that seagate with something else. Even if you get it up and running there is no trusting it to stay doing so. I recommend an XT-IDE and a ~512Mb CF card. Makes the machine so much more functional.

    IBM 5160 - 360k, 1.44Mb Floppies, NEC V20, 8087-3, 45MB MFM Hard Drive, Vega 7 Graphics, IBM 5154 Monitor running MS-DOS 5.00
    IBM PCJr Model 48360 640kb RAM, NEC V20,, jrIDE Side Cart, 360kb Floppy drives running MS-DOS 5.00
    Evergreen Am5x86-133 64Mb Ram, 8gb HDD, SB16 in a modified ATX case running IBM PC-DOS 7.10

  10. #10
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    Quote Originally Posted by VintageVic View Post
    Is it that thingy, which is touching in the center of the spindle ?
    That thing grounds the spindle. During this time of diagnosis, it can be removed.

    Quote Originally Posted by VintageVic View Post
    oh. I will try to post a pic here (if i'm allowed to do so).
    I do not see any external brakes there, that I could remove.
    I see no braking mechanism.

    Quote Originally Posted by VintageVic View Post
    This one is indeed stuck. It will turn maybe about 5mm to each direction, then there is resistance significant enough to discourage me to push harder.
    Confirm for us that the 5 mm is at the outer edge of the spindle.

    If that is the case, and if there is a head stuck to the platter, then I would expect up to 2 mm at the outer edge of the spindle (the give being between the head arm and the head). Others may comment on that.

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