I think it's the platter's motor that's bad and not the heads that are stuck to the platters. Old HDD tend to have bad bearings after a while. What you can do when it's off is to take it in your hands, turn it quickly and stop immediately after. Repeat several times and check if it spins up this time. This should unstick the bearings.

Deksor wrote on 2020-01-31, 11:23:

I think it's the platter's motor that's bad and not the heads that are stuck to the platters. Old HDD tend to have bad bearings after a while. What you can do when it's off is to take it in your hands, turn it quickly and stop immediately after. Repeat several times and check if it spins up this time. This should unstick the bearings.

According to this link: http://www.mcamafia.de/mcapage0/problem1.htm#probl01 the drive I have can seize up in that way.
After spinning it for quite a while it still isn't spinning up, but it does spin sort of freely when I spin it by hand. It stops directly after I stop spinning though.

ThatRetroDude wrote on 2020-01-31, 13:02:

After spinning it for quite a while it still isn't spinning up, but it does spin sort of freely when I spin it by hand. It stops directly after I stop spinning though.

You can feel the platters spin? You sure about that? Because if it does spin at all, it's not stuck - this is caused by the heads "sticking" to the platters so neither can move. If the spindle is not in fact stuck then probably it's the motor driver chip that is toast - not much can be done about that other than replacing it. I'd argue the disk is gone and that's it.

If it is still stuck, and you only want it to spin one last time to make a backup copy, then open it up and free the spindle by GENTLY rotating it with your finger, placed on the edge of the platter(s). Direction is important too, the heads should be parked near the center (but might not be, and that's why it's stuck). Rotate it a bit so the heads are "dragged" along with the rotation direction and move on their own towards the center (or just stay if already there).
Once opened the dust that gets inside will kill it, eventually, and most likely it will get stuck again pretty soon anyway. So it's really the last resort and one-time operation.

The data density is so low in these drives that dust won't really hurt them like it does in more modern drives.

Deunan wrote on 2020-01-31, 14:01:

If it is still stuck, and you only want it to spin one last time to make a backup copy, then open it up and free the spindle by GENTLY rotating it with your finger, placed on the edge of the platter(s). Direction is important too, the heads should be parked near the center (but might not be, and that's why it's stuck). Rotate it a bit so the heads are "dragged" along with the rotation direction and move on their own towards the center (or just stay if already there).
Once opened the dust that gets inside will kill it, eventually, and most likely it will get stuck again pretty soon anyway. So it's really the last resort and one-time operation.

I have tried to open it unsuccessfully twice. I do not have the right torx screw drivers for it. And yes, I do hear something faintly spinning when I shake it back and forth, but as soon as I stop spinning, the platter(s) stop too. I'd guess the motor or the chip is toast.

Do not open it up. Wiggle computer when instant it is turned on to try to free up the platters. If it is. and stuck again on next powered off, then look into MCA scsi card and scsi drive. Have to splice 12V and 5V and two ground wires for the drive.

Cheers,

“Stiction” from lubricant breakdown was a real problem with early 3.5 inch drives.. sometimes the heads would stick. Try the wiggle at power on , or try warming the drive up to a few degrees above room temperature to soften the lubricants.

Opening up the drive could work but it’s sort of a last resort. No going back from that.

pentiumspeed wrote on 2020-01-31, 21:27:

Do not open it up. Wiggle computer when instant it is turned on to try to free up the platters. If it is. and stuck again on next powered off, then look into MCA scsi card and scsi drive. Have to splice 12V and 5V and two ground wires for the drive.

Cheers,

Power the drive up with a stuck bearing is also stupid.. Then the coil of the motor will getting to hot and it will burn that motor.. So then its also a dead drive, because of motor failure.
Sometimes its beter the open up the drive and see if the platter isnt scratched. Only do this with caution and in a limited dusty environment.

pentiumspeed wrote on 2020-01-31, 21:27:

Do not open it up. Wiggle computer when instant it is turned on to try to free up the platters. If it is. and stuck again on next powered off, then look into MCA scsi card and scsi drive. Have to splice 12V and 5V and two ground wires for the drive.

Cheers,

Going to try that then. It was however getting quite warm after 20 minites or so flashing the LED and making desperate attempts to spin up. And when I got this PS/2 from my local school the hard drive was unplugged and there was a floppy in the drive whoch makes me think that the hard drive bas been like that since at least '95 or so.

Old thread resurrection alert 😀

I have the same drive doing the same thing. I can sometimes get it to start by taking it out, spinning it (you can hear the platter move inside) and putting it immediately back in - after about 20 attempts it might start! Once the drive is spun up it works absolutely fine and you can turn it off and on no problem as long as it's off for no more than about an hour.

Is it the motor or is there anything obvious I can try to replace on the circuit board that might have failed (like old capacitors)? Everything looks just fine with no leaking.

Cheers,
Steve

Yes, power up and within few seconds the rotate the computer itself or rotate with a jerk that hard drive. I have done that before with ST125 MFM that still works perfectly but stuck when cold that was given to me along other cast off parts back in the day. ST125 is 3.5" MFM stepper which is same mechanism as yours when I had junk 286 computer that I would put together at dad's place or at my mom's home to play bit of games. The whole kit is disassembled in a cardboard box for travel along with TTL monochrome monitor when I was late teens. No case as I don't have money for that and too young.

Experience shows these:
ST1xx with stepper design if they were allowed to run hot due to poor cooling they developed heads stuck on platters. If the computer had good cooling to keep these hot running hard drive cool (same with early quantum 3.5" HH or 1" height (mostly LPS model) they will not develop this sticky disease. In other words, if you have a early 3.5" hard drive that run hot, above 50C to 60C they will stick, install fan next to these and they will last long time.

Cheers,