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Thread: Restoring a Micropolis SCSI-1 drive

  1. #1
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    Default Restoring a Micropolis SCSI-1 drive

    I have a Micropolis 1375 that was gifted to me. It had been in storage for a couple of decades, the original owner thought it would DOA. This is a full height 5.25" 146MB SCSI-1 drive. Expecting it to be DOA, I fired up the computer it was installed in and it booted! It took me a couple reboots to get some media attached so I could start copying off files. I got 40MB copied with no errors whatsoever, went to reboot to install a new device to hold the next 40MB, and the drive will boot never more. Overall about 2 hours total elapsed between powering it up the first time and the failure. It seems to hang in an unready state. The original computer eventually times out. Putting the drive in a Linux box (what I would have done in the first place had I expected it to be viable) shows that it's reporting a generic "not ready" code.

    It is spinning, so it's not a stiction issue. and the reboot that caused it to cease functioning was only about a minute long. There are some RPM variations, approximately every minute or two it spins down by about 30% and then spins back up. Not sure if this is a problem, or some algorithm in the drive trying to compensate for whatever is wrong. Eventually after behaving like this for about 10 minutes or so, it will spin down entirely. The head and positioning mechanism is entirely inside the sealed chamber, so there's no way for me to tell if it's seeking (don't hear any seek noise).

    What are my options? I did order a same model "tested good" drive from ebay, and assuming that drive does indeed "test good" when I get it, I'll try a controller swap.

    If the controller swap fails, is there any viability in opening up the sealed compartment and taking a look? I've always behaved as if doing so would instantly and catastrophically destroy a HDD, but I don't know if that's really true. The drives do feature an automatic parking mechanism and for all I know that parking mechanism could just be stuck, or some other simple fix.

    The data on the drive is not of significant monetary value, so paid restoration is probably not reasonable. It does have sentimental value to the original owner, has value to me as a hobbyist, and some portion is perhaps contributable to the public domain depending on intellectual property issues that would have to be looked into.

    Scott

  2. #2
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    I've seen this in a big Maxtor drive too--eventually, it didn't have the moxie to even start spinning. I chalked it up to a lubrication issue and put the drive back on the shelf.

  3. #3
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    The spindle feels to me like it's fine. I mean, I don't exactly know what it's supposed to feel like, but it doesn't feel like it's out of balance or like it has an excess of friction.

  4. #4

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    Stuck heads on drives are common to some models. I've seen it on Micropolis and Maxtor. Do you remember if they seeked on your first power up? Most drives do a calibration seek on power up so no seek either indicates it doesn't think its up to speed or the heads won't move. I have done some repairs on 1325 drives. The spin down and back up is common on drives that think they have problems and are retrying. On the 1325 if the heads aren't over the correct portion of the track they don't pick up the servo data so can't switch to the fine servo speed control. I had to put a shim in to get them over the proper area.

    http://www.pdp8online.com/rd53/rd53.shtml

  5. #5
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    Since you are going to try changing the drive's circuit board anyway, I would try just working all the connectors on the drive off and back on to see if the issue is just oxidation. I have had this help several old hard drives. Might not be the problem for sure, but a couple of decades just sitting in storage is a good recipe for causing this condition.

  6. #6
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    Quote Originally Posted by djg View Post
    Stuck heads on drives are common to some models. I've seen it on Micropolis and Maxtor. Do you remember if they seeked on your first power up?
    The first power up booted the computer, so it was seeking correctly.

    These recent attempts, as far as I can tell there is no seek. But then again without a working drive to use as an example, it's hard for me to be sure what to listen for. I know what a stepper should sound like on an old MFM drive (and I'm clearly not hearing stepping!), but could these SCSI drives be voice coil? Couldn't find much details on the 1375.

    These rubber bumpers sound like an excellent working theory. During my two hours of successful operation, maybe the drive warmed up a bit, power off and heads get stuck on the bumper. My gut feeling is that it's not seeking.

    Quote Originally Posted by fatwizard
    Since you are going to try changing the drive's circuit board anyway, I would try just working all the connectors on the drive off and back on to see if the issue is just oxidation
    I'm not sure I mentioned this in the OP, but I do actually have two of these drives. One was DOA when I received it, the other is the one I've been describing in this thread (worked for a few hours, then failed after a reboot). I did swap the controllers between the two and neither exhibited any difference in behavior. But that could just mean both have fallen to the exact same issue, which could in theory be bad controllers. Mechanical problem does seem more likely than two bad controllers though.

    I think my plan of attack is going to be:

    1) Verify that the "tested good" eBay drive is good, and that my Linux box is able to read from it (this also verifies I have Linux configured correctly).

    2) Try the eBay drive's controller on my broken drive(s). If that fixes the problem, great.

    3) Pop open the case and look for stuck heads. This is the last resort.

    I'm itching to short circuit step 1 and just crack open the case and see if the heads are stuck, but I don't know if that's the wisest course of action.

  7. #7
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    I don't have this model drive, but the SCSI drives I do have from that era definitely make a sound when they come ready. They spin up, then a muttering or shuffling or winding sound of some kind, as the heads are moved out to find track 0. Wait on the drive from eBay. If it works you'll hear it come ready. Then you can try the board transplant. The full height 5.25" drives were pretty robust, I kinda doubt the heads are physically stuck if it's spinning up. Open it as a last resort.

  8. #8
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    Quote Originally Posted by fatwizard View Post
    I don't have this model drive, but the SCSI drives I do have from that era definitely make a sound when they come ready. They spin up, then a muttering or shuffling or winding sound of some kind, as the heads are moved out to find track 0. Wait on the drive from eBay. If it works you'll hear it come ready. Then you can try the board transplant. The full height 5.25" drives were pretty robust, I kinda doubt the heads are physically stuck if it's spinning up. Open it as a last resort.
    I think you're right, I ought to just be patient.

  9. #9
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    Opening up a drive can introduce a lot of contaminants which could eventually lead to a head crash and destruction of the disk(s). The older and lower density the drive the better chance you could get possibly get away with it. Tolerances have shrunk continuously on hard drives and it doesn't take much to cause fatal problems on a modern drive.

  10. #10

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    have you got sg_utils? it might be able to probe the drive and get some further info, though may just tell you it's not ready.

    http://sg.danny.cz/sg/sg3_utils.html

    You will probably need the -6 option on a drive that old.

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