Seagate ST-251 MFM HD problem

[jwd]

I have found my old ST251-1 HD from my parents loft and even though I should have all the Atari stuff off it when i moved to my Falcon I would still like to check a do a proper copy of everything from it if i can.

Problem is when power is applied (nothing else connected) it spins up fine but doesn't do the head seek/calibration bit and so is stuck in its parked area.

I have moved the heads out manually and powered down, the stepper motor correctly auto parks the heads.

I have replaced the 2 power capacitors on the main control board as mentioned here :

https://www.lo-tech.co.uk/wiki/Seagate_MFM_Hard_Drive_Repair_Notes

to no avail, the logic would suggest get another ST251-1 off fleabay and swap the control board, as with anything retro now the prices are ridiculous, so would anyone have any ideas why the drive won't calibrate/seek after spinup and/or things to try?

Or even suggest another (Retro PC) forum that could help?

thanks

[stephen_usher]

It's probably the "rubber" bumper for the head arm which has turned to goo and is sticking the arm in place. Unfortunately a common and often terminal fault.

[jwd]

This is exactly what it sounds like (link starts at 1:09) :



Spins then a small strain sound then nowt (except spin). Drive therefore doesn't initialise.

[jwd]

It's probably the "rubber" bumper for the head arm which has turned to goo and is sticking the arm in place. Unfortunately a common and often terminal fault.

yeh i had a thought it was sticky but moved the arm into the middle then spun it up again, didn't move except to put it back into park when the power was taken away.

[czietz]

Looking at the PCB (http://bitsavers.informatik.uni-stuttga ... T251_f.jpg), many of the chips are Seagate ASICs apparently (and, thus, unobtainium). But I do see that the µC has a 2732 EPROM connected to it, a dump of which someone also put at Bitsavers, along with the schematic: http://bitsavers.informatik.uni-stuttga ... fm/ST-251/. Reprogramming the EPROM (after dumping the original contents) might be worth a try.

EDIT: I need to add the usual disclaimer. If the data is really valuable (as in: worth a lot of money), it's always best to hire a data recovery company. In that case, I strongly advise against any repair attempts, as they might reduce the chance of successful recovery by the professionals.

[jwd]

another forum suggested using the 'life test' jumper setting :

When pins 7-8 of J7 are shorted, the
stepper motor will continuously seek between Track 0

No action from the drive when this jumper applied so if the stepper can move the head back to park (if manually brought out by hand) but not action this function I would guess that points to the board logic is dead as your suggesting.

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

Don't suppose anyone on this forum has a ST251-1 I could borrow/buy for its logic board ?

thanks

[tzok]

I also had no reaction from this jumper on a drive with bad track 0. However, I've eventually managed to initialize low level format and disk went back to life.

[jwd]

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 the controller board and host adapter (which i know works as have it running with a ST225 fine) the drive is not seen but at least i can here 'trying' from the drive when the controller is communicating.

Probably need an IBM XT with ISA MFM board for some low level stuff (Spinrite etc.) as nowt for Atari in that sense.

Progress albeit slowly . . .