19 Oct
2016
19 Oct
'16
9:20 p.m.
I have a couple of drives I would really like to recover the data from.
On one of the two I've tried so far, the lowest head in the stack is really stuck on.
Has anyone successfully unstuck a head from this era. I've tried the obvious things
(gentle rotation in both axis, heating the platters) but there is a lot of surface
area on those old heads and it is pretty badly stuck.
19 Oct
19 Oct
9:25 p.m.
A good bang in the side with the heavy side of a screwdriver uses to work
flawlessly ;) (sometimes 2 or 3 bangs :D )
2016-10-19 23:20 GMT-02:00 Al Kossow <aek at bitsavers.org>:
I have a couple of drives I would really like to
recover the data from.
On one of the two I've tried so far, the lowest head in the stack is
really stuck on.
Has anyone successfully unstuck a head from this era. I've tried the
obvious things
(gentle rotation in both axis, heating the platters) but there is a lot of
surface
area on those old heads and it is pretty badly stuck.
9:40 p.m.
On Oct 19, 2016 9:25 PM, "Alexandre Souza" <alexandre.tabajara at
gmail.com>
wrote:
A good bang in the side with the heavy side of a screwdriver uses to work
flawlessly ;) (sometimes 2 or 3 bangs :D )
2016-10-19 23:20 GMT-02:00 Al Kossow <aek at bitsavers.org>:
> I have a couple of drives I would really like to recover the data from.
> On one of the two I've tried so far, the lowest head in the stack is
> really stuck on.
> Has anyone successfully unstuck a head from this era. I've tried the
> obvious things
> (gentle rotation in both axis, heating the platters) but there is a lot
of
> surface
> area on those old heads and it is pretty badly stuck.
>
>
>
Put in the oven, 150 degrees, 2 mins on a
Side for 8 minutes total
Bill Degnan
twitter: billdeg
vintagecomputer.net
20 Oct
20 Oct
5:05 a.m.
I actually years ago unstuck drives by removing them, hooking them to
cables long enough to allow me to have access to them external to the
system with power, and just holding them in the air and giving them a
sharp twist around the axis of the drive. That was enough to unstick
most. I also had ready a drive on the systems to drain or recover data
immediately prepped on the system in advance (Windows 95 and NT days).
Never forced or heated them, may work as well. I thought the force if
applied quickly would cause not only "stiction" to be be overcome from
heads temporarily stuck to the drive, but it also gives a bit of a boost
in case the poles on the motor were not working well enough to give a
kick to start the spin, which is a different problem.
The latter seemed to be the problem of at least a couple of drives, as
they would start if you gave them a prod, but otherwise were either
silent or humming (from the pole forces oscillating rather than causing
successive action to spin the platters).
thanks
Jim
On 10/19/2016 6:40 PM, william degnan wrote:
On Oct 19, 2016 9:25 PM, "Alexandre Souza"
<alexandre.tabajara at gmail.com>
wrote:
A good bang in the side with the heavy side of a
screwdriver uses to work
flawlessly ;) (sometimes 2 or 3 bangs :D )
2016-10-19 23:20 GMT-02:00 Al Kossow <aek at bitsavers.org>:
> I have a couple of drives I would really like to recover the data from.
> On one of the two I've tried so far, the lowest head in the stack is
> really stuck on.
> Has anyone successfully unstuck a head from this era. I've tried the
> obvious things
> (gentle rotation in both axis, heating the platters) but there is a lot
of
> surface
> area on those old heads and it is pretty badly stuck.
>
>
>
Put in the oven, 150 degrees, 2 mins on a
Side for 8 minutes total
Bill Degnan
twitter: billdeg
vintagecomputer.net
10:07 a.m.
On 10/20/16 2:05 AM, jim stephens wrote:
I actually years ago unstuck drives by removing them,
hooking them to cables long enough to allow me to have access to
them external to the system with power, and just holding them in the air and giving them
a sharp twist around the axis
of the drive. That was enough to unstick most.
I will probably just set this one aside for the day I have access to a spin stand
and a pair of heads moved with D/As.
The simple tricks work if the spindle bearing is gummy, or the head is slightly stuck.
This one is bad enough you can see the flexure twist.
It is going to have to be disassembled.
It is out of a pair of Gould 68000 development systems that I got from Erik Klein. Very
unusual boxes built out of Valid Logic 68K multibus boards, with their own SASI and
serial
interface cards and 3com ethernet, running Valid's 4.1BSD. So far, I've been able
to recover
most of the root file system disk. The usr disk is the one with the stuck head. I have
one
more pair of drives from the other unit, I'm hoping either they come up, or there are
enough
sectors that aren't bad that I can piece together the file system. I can see the
header files,
so at least I have some information on how you talk to their boards.
David Gesswein has been a huge help through this whole effort. The Adaptec 4000 was set up
for
18 sectors/trk, and he modified mfm_read to get that working with these drives.
12:23 p.m.
The two disks this morning went much better. I tried using a heat gun on the outside of
the hda and VERY
gently freed the heads and got the spindle to turn. Then I pulled the top board and coaxed
the spindle motor
back up to speed. The root disk read without errors, usr has a consistent 28.
The same experiment didn't work on the usr disk from the first system though :-(
At least now I have a good root image and probably usuable usr
On 10/20/16 2:05 AM, jim stephens wrote:
I actually years ago unstuck drives by removing
them, hooking them to cables long enough to allow me to have access to
them external to the system with power, and just holding them in the air and giving them
a sharp twist around the axis
of the drive. That was enough to unstick most.
12:42 p.m.
I've got several ST251-1s that spin up just fine, no funny noises, but then do a bunch
of back-and-forth seeks and shut down again.
It's the usual, "they worked fine the last time;" any ideas what the problem
is and if there's anything that can be done? Presumably it's having trouble
finding the sync track; weak signal? Any ideas?
m
----- Original Message -----
From: "Al Kossow" <aek at bitsavers.org>
To: <cctalk at classiccmp.org>
Sent: Thursday, October 20, 2016 12:23 PM
Subject: Re: Unsticking a Seagate ST-419 head
The two disks this morning went much better. I tried
using a heat gun on the outside of the hda and VERY
gently freed the heads and got the spindle to turn. Then I pulled the top board and
coaxed the spindle motor
back up to speed. The root disk read without errors, usr has a consistent 28.
The same experiment didn't work on the usr disk from the first system though :-(
At least now I have a good root image and probably usuable usr
On 10/20/16 2:05 AM, jim stephens wrote:
I actually years ago unstuck drives by removing
them, hooking them to cables long enough to allow me to have access to
them external to the system with power, and just holding them in the air and giving them
a sharp twist around the axis
of the drive. That was enough to unstick most.
4:25 p.m.
On Thu, 20 Oct 2016, Mike Stein wrote:
I've got several ST251-1s that spin up just fine,
no funny noises, but then do a bunch of back-and-forth seeks and shut down again.
It's the usual, "they worked fine the last time;" any ideas what the
problem is and if there's anything that can be done? Presumably it's having
trouble finding the sync track; weak signal? Any ideas?
m
I'm actually trying to bring an ST251-1 back to life right now. It
worked, then was intermitently not recongnized by the controller after
being powered on for a while, now not recognized at all. When you apply
power it runs through whatever standard head-sweep routine (self-test?),
but there seems to be a communication breakdown between the Drive
electronics and controller board.
Various sources on the interwebs suggest me that the small SMD tant caps
by the power connector are a known issue on these drives and can lead to
all sorts of flaky behavior.
I've orderd a few from digikey, hopefully will have them by this weekend
to attempt a repair.
See my forum post here, where my shoot-in-the dark analsys is disagreed
with:
http://www.vcfed.org/forum/showthread.php?54516-Caps-for-an-ST251-1:
--Jason
4:38 p.m.
On Thu, Oct 20, 2016 at 4:25 PM, Jason Howe <jason at smbfc.net> wrote:
On Thu, 20 Oct 2016, Mike Stein wrote:
I've got several ST251-1s that spin up just fine, no funny noises, but
Can you swap the controller board of the drive with another drive's?
then do a bunch of back-and-forth seeks and shut
down again.
It's the usual, "they worked fine the last time;" any ideas what the
problem is and if there's anything that can be done? Presumably it's having
trouble finding the sync track; weak signal? Any ideas?
m
I'm actually trying to bring an ST251-1 back to life right now. It
worked, then was intermitently not recongnized by the controller after
being powered on for a while, now not recognized at all. When you apply
power it runs through whatever standard head-sweep routine (self-test?),
but there seems to be a communication breakdown between the Drive
electronics and controller board.
Various sources on the interwebs suggest me that the small SMD tant caps
by the power connector are a known issue on these drives and can lead to
all sorts of flaky behavior.
I've orderd a few from digikey, hopefully will have them by this weekend
to attempt a repair.
See my forum post here, where my shoot-in-the dark analsys is disagreed
with: http://www.vcfed.org/forum/showthread.php?54516-Caps-for-an-ST251-1:
--Jason
4:47 p.m.
On Thu, 20 Oct 2016, william degnan wrote:
On Thu, Oct 20, 2016 at 4:25 PM, Jason Howe <jason
at smbfc.net> wrote:
I would if I had a spare ST251-1 hanging around. I've been tempted to
order one from the flea-bay for just such an experiment.
--Jason
On Thu, 20 Oct 2016, Mike Stein wrote:
I've got several ST251-1s that spin up just fine, no funny noises, but
Can you swap the controller board of the drive with another drive's?
then do a bunch of back-and-forth seeks and shut
down again.
It's the usual, "they worked fine the last time;" any ideas what the
problem is and if there's anything that can be done? Presumably it's having
trouble finding the sync track; weak signal? Any ideas?
m
I'm actually trying to bring an ST251-1 back to life right now. It
worked, then was intermitently not recongnized by the controller after
being powered on for a while, now not recognized at all. When you apply
power it runs through whatever standard head-sweep routine (self-test?),
but there seems to be a communication breakdown between the Drive
electronics and controller board.
Various sources on the interwebs suggest me that the small SMD tant caps
by the power connector are a known issue on these drives and can lead to
all sorts of flaky behavior.
I've orderd a few from digikey, hopefully will have them by this weekend
to attempt a repair.
See my forum post here, where my shoot-in-the dark analsys is disagreed
with: http://www.vcfed.org/forum/showthread.php?54516-Caps-for-an-ST251-1:
--Jason
5:08 p.m.
New subject: ST-251 [was Re: Unsticking a Seagate ST-419 head]
On 10/20/16 1:25 PM, Jason Howe wrote:
I'm actually trying to bring an ST251-1 back to
life right now. It worked, then was intermitently not recongnized by
the controller after being powered on for a while, now not recognized at all. When you
apply power it runs through
whatever standard head-sweep routine (self-test?), but there seems to be a communication
breakdown between the Drive
electronics and controller board.
Just did my usual sweep for schematics, and there is one up now
http://www.dasarodesigns.com/schematics-and-resources/
There was a guy on ebay selling off individual sheets of reverse-engineered schematics,
and he bought them all and put them on line!
2841
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10 comments
6 participants
participants (6)
-
aek＠bitsavers.org -
alexandre.tabajara＠gmail.com -
billdegnan＠gmail.com -
jason＠smbfc.net -
jwsmail＠jwsss.com -
mhs.stein＠gmail.com