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Help with Seagate ST251 hard drive

DonutKing

Experienced Member
Joined
Mar 24, 2011
Messages
96
Location
Gold Coast, Australia
Hi,
I have an ST251 in my 286 machine which has been a bit temperamental lately.
It's quite erratic, you can hear it spin up on boot but occasionally it just won't get detected at POST.
Sometimes I'll be using it for an hour or so and i'll get a Seek Error or Sector Not Found, and the C drive becomes no longer available - then on reboot it won't get detected.
If I power off the machine at this point I hear it spin down and park the heads.

I know these drives are notorious for stiction but the fact that I can still hear it spinning makes me think this isn't the problem. I think its making all the right noises (these drives have some pretty unique noises so it can be hard to tell :) )

I did come across this page: http://home.earthlink.net/~z100lifeline/data/HDrive.html which suggests replacing the two 22uF surface mount caps near the power connector with 47uF ones. Has anyone heard of or tried this fix?

The guide suggests using electrolytic caps but I can get 47uF 20v surface mount tantalums which will fit a bit better, shouldn't be a problem if I use those should it? Soldering isn't a problem as I've done plenty of that before.

I took the controller board off to have a look, unfortunately I didn't make a note of which way the 10-pin cable attaches at the end of the board near the ribbon cable connecter before I removed it- every wire is a different colour and the connector isn't keyed. I don't suppose anyone could tell me the correct orientation for this connector? (The other cable near the middle of the board is keyed)

Thanks :)
 
Last edited:

pearce_jj

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May 14, 2010
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UK
Which version of the drive? If it's an ST251-1 I can help with the connector orientation later.
 

MikeS

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Dec 23, 2005
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Toronto ON Canada
Which end of the cable? On the drive pin one is (always AFAIK) the end closest to the key notch (i.e. towards the power connector, same as the control cable).

The 251-1 is identical to the 251, only slightly faster.

As long as voltage and capacitance are the same or slightly higher, tantalums should do just as well as electrolytics.

You might try backing it up and doing a low-level format; sometimes as drives of this type age and parts wear a bit the heads end up slightly off the tracks and it may help to redo the tracks.
 
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DonutKing

Experienced Member
Joined
Mar 24, 2011
Messages
96
Location
Gold Coast, Australia
This is the cable I'm talking about:

2tupa.jpg


Underside of the controller board, opposite end to the data/power connectors.
It was so difficult to remove that small ribbon connector that I popped that cable off without noticing its orientation and it's not keyed.

Judging by the angle that has been pressed into the wires, I think that is the correct orientation in the picture but I'd like to confirm before I power it on.


I take it nobody here has heard of or performed this capacitor replacement on old Seagate drives?
 

mikey99

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Jun 15, 2006
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Location
NC , USA
I think I may have an ST-251 out in the garage, will take a look tomorrow to check the cable orientation.
 

MikeS

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Dec 23, 2005
Messages
7,510
Location
Toronto ON Canada
Judging by the angle that has been pressed into the wires, I think that is the correct orientation in the picture but I'd like to confirm before I power it on.
Had to look at two because the first one used a ribbon cable, but you've got it right.
I take it nobody here has heard of or performed this capacitor replacement on old Seagate drives?
I haven't, and I doubt that it'll make any difference, but it can't hurt.
 

DonutKing

Experienced Member
Joined
Mar 24, 2011
Messages
96
Location
Gold Coast, Australia
Just following up on this. I finally got around to replacing the caps. I just used 47uf 25V radial electrolytics and bent them down so they fit between the drive and the board.

So far so good. Although the issues I was having were erratic, they'd usually show up within an hour of disk activity like copying files etc. I've been running it for a couple of hours now doing various taskss like copy files, defrag and benchmark using norton utils, and playing a few games and haven't had any problems.

So, if you have a flaky ST251 this might be a way to squeeze a bit more life out of it.
 
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