What controller are you using?
Is it the same as last time?
When was the last time, like several years ago?

fool wrote on 2023-01-11, 13:02:

What controller are you using?
Is it the same as last time?
When was the last time, like several years ago?

Not using any controller as it won't spin up like it used to without connection, without any connections it should spin-up then calibrate/seek test heads, doesn't do the calibrate/seek test bit so purely drive problem.

I would say 15 years at least when it last worked.

I have "fixed" few Seagate MFM drives just by low level formatting. These old MFMs like to lose data over time (in 20-30 years). I cannot recall was there a drive that didn't seek before LLF.

Would be interesting if it can be LLF'd, but it wipes all the data of course and that's not what you want.

Thing is as the drive doesn't initialise no controller card will see it.

Something wrong directly with the drive mechanics or its onboard electronics. As there were so many of these about yesteryear and even videos of my exact problem I thought it would be quite a common solution although i can find nothing on the internet as to what exactly this behaviour indicates

MFM drives are generally dumb and doesnt do much without control. I would not say its faulty without first connecting it to one or two controllers.

Is jumper J7 9-10 accessible? It should start seek test, not recommended by the manual (so must do). That would give answer is the stepper faulty. I have not used it ever and cannot say how it should behave.

I would perform some tests with Speedstor (sstor.exe). You can boot from floppy with the faulty drive installed. The seek test works also if the drive is not correctly formatted and you can hear the heads moving.

fool wrote on 2023-01-11, 18:52:

MFM drives are generally dumb and doesnt do much without control. I would not say its faulty without first connecting it to one or two controllers.

Is jumper J7 9-10 accessible? It should start seek test, not recommended by the manual (so must do). That would give answer is the stepper faulty. I have not used it ever and cannot say how it should behave.

Thanks for the tip, I used the following manual :

http://www.ataripc.net/wp-content/uploads/Sea … Manual-1987.pdf

and i think you are referring to the 'Life test' on shorting jumpers 7-8 ?

I tried it and nowt, same behaviour. When using a torx screwdriver to move the stepper manually when powered I can feel that the stepper motor is energised (different from no power) so power is getting to the stepper motor (also moves head to park area on power off if i've moved head manually), seems to point to on board stepper control electronics.

🙁

I referenced to this https://stason.org/TULARC/pc/hard-drives-hdd/ … -MFM-ST412.html
As it's ST251-1 right?

1J7  Factory Test Jumper
2 -----------------------
3 x    9-10  OPEN
4      9-10  CLOSE  Actuator seeks continuously
5
6This is a test function used during the manufacturing process and is
7not recommended for field use.
8When pins 9-10 at J7 are shorted, the actuator will continuously seek
9between Track 0 and the maximum data cylinder, ignoring control
10signals sent via interface.

ST251 is 6 heads with bit more cylinders, 17 sectors which is MFM. Not RLL.

Listen to it. Should not grind at one stop ever, if so it is out of adjustment and not salvageable. At turn on, the arm should whir and touch one stop quietly, then make few plays of seeking then stop. Watch the stepper shaft. If it look stay there with grinding sound. No good.

I collected several of these (ST225, 251 and ST125, ST157 and eventually called them the fussy drives and easy to destroy, bearing wears out easily, and fussy with stop setting and board burns out on occasion.
The spindle shaft is mounted to a hub at far end near the platter clamp and shaft is soft metal. Easy to bend results in wobble.
Back in the day, I learned not to have stepper hard drive and went directly for voice coil hard drive, that was around 1991 was ST1102A in 386DX 25 computer. Only one computer that was donated new to me without my choosing was miniscribe 20MB stepper in EazyPC, didn't like this computer at all. Mono, and Nec V30 not too compatible.

This is good ST251 start up what it looks like and sounds like.
https://www.youtube.com/watch?v=n_1XrZTJ7hY

Common bent shaft with mishandled hard drive.
https://www.youtube.com/watch?v=P0ttS85lg08

I never had a PC I owned with stepper ever due to this causes of failures analysis on donated dead and dying stepper hard drives: Seagate, Miniscribe, Tandon/WD and several others.

Cheers,

fool wrote on 2023-01-13, 17:24:

I referenced to this https://stason.org/TULARC/pc/hard-drives-hdd/ … -MFM-ST412.html As it's ST251-1 right? […]
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I referenced to this https://stason.org/TULARC/pc/hard-drives-hdd/ … -MFM-ST412.html
As it's ST251-1 right?

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1J7  Factory Test Jumper
2 -----------------------
3 x    9-10  OPEN
4      9-10  CLOSE  Actuator seeks continuously
5
6This is a test function used during the manufacturing process and is
7not recommended for field use.
8When pins 9-10 at J7 are shorted, the actuator will continuously seek
9between Track 0 and the maximum data cylinder, ignoring control
10signals sent via interface.

Ah yes, same jumper just labelled differently in each document.

No action from the drive when this jumper applied so if the stepper can move the head back to park but not action this function I would guess that points to the board logic is dead?

Just need another ST251-1 board to swap out but $800 on ebay for these drives!!

Make sure the hard drive spin up. Right after power up, turn the hard drive sharply. If it spins up then platters is stuck to the heads.

Cheers,

The head can move across the platter with no problem when either moved manually or moving the heads into the parked position so no sticking it seems.

Possibly a faulty stepper motor driver IC, or maybe one of the coils in the motor is open? I don't have much experience with MFM drives but the in very first ones stepping was a very dumb circuit simply following a pulse on the control like - like in floppy drives, even required that the signal is not pulsing too fast (6 or 3 ms or so between steps). Later drives will count even faster pulses and do the timing internally. In general this can be tested with a simple button or switch if the power is applied - might need debouncing though.

Just an update on this if anyone is interested.

I managed to find a donor ST251-1 drive in good condition and most important cheapish. Swapped the logic board and powered up, this time with the correct sounds and seek test after spinup as it should, yay!

Now when connecting to my controller board its not seen but at least i can here 'trying' from the drive when the controller is communicating.

Progress albeit slowly . . .