hard drive data recovery

From: Allison J Parent <allisonp_at_world.std.com>
Date: Sat Jul 11 22:10:59 1998

< I'e thought about making a plastic (perspex/plexiglass) box with the
< fan/filter from a demountable drive (I have that sort of thing in my junk
< box) to blow clean air into the unit. Then take the drive apart, fix it,
< put it back.

A plastic box with a blower and a HEPA filter from one of these new vacuums
to put clean air in the box at positive pressure. The front would be clear
with rubber gloves to allow reaching in. level of clean can easily excees
class 100. Adaquate for sophisticated drive repairs.

< 1) Open up a drive, repair it in a minor way (say replace a pre-amp chip
< on the flex cable, replace the end stops, that sort of thing), and have
< it run long enough to get the data off it.

I've done this on at least 4 micropolus 1325s (rd53, 71mb) that had gummy
end stops and one that had a misset end stop!

none have been under special conditions described.

I also have a st506 that I put a plexi cover on about 10 years ago, still
runs though not currently in use (has CP/M on it).

< 2) Open up a drive, or several drives, and move parts around, including
< heads and platters, to make a working drive that'll run for quite a long
< time. Long enough to think of installing it in a classic computer that I
< was using.

Never considered this. though I have several I could experiment on.

<
< Doing (1) means you have to be able to align heads, etc, over the
< existing tracks on the media. Doing (2) probably requires a lower dust
< particle count.

Not really.

< > filtering, or is it absolutely required? Can a drive be opened in room
< > air and be worked on without introducing dangerous dust particles onto t

Look at the air flow and realize that dust on the platter is suffering from
centrifical force of the platters at 3600 rpm. There is an amazing amount
of moving air trying to send everything to the periphery!

< > Why can't they make a hard drive that's crash proof? Even if the
< > mechanics fail, can't some hardend substance like glass be layed over th
< > platter so if the head did crash it would only scratch the glass? Then
<
< Remember that as data density increases, you need to lower the flying
< height of the head. That's why demountable drives have a lower capacity th
< winchesters of the same period. The demountable has to have a higher
< flying height due to the fact that it's 'dirtier'.

All true but... the newer drive are plated metal (cobalt and nickle are
hard!) and some of the substrates used are ceramic and even glass for
rigiditity.

< The old drum stores had fixed heads. The height was set by the screw
< mounts of the heads - and in general it was quite high because of
< mechanical errors in making the thing. The flying heads of the hard disks
< meant that the head would follow slight run-out in the platter, allowing
< a lower flying height and higher density.

The problem there was bearing runout, the concentricity of the drum and
it's size setting up mechaical vibrations. Later drums would float the
head on a spring and didn't suffer many of the problems as they could
float.

< For this reason, I think it's possibly realistic to consider working on
< 50Mbyte and below - maybe up to 100Mbyte - winchesters at home, given a
< clean box. I personally feel that the 1.2Gbyte 2.5" units will not be
< capable of being repaired in a clean box, though - the flying height is
< just too low. But I'd love to be proved wrong.

I ran an old 320mb 3.5" conner with the cover off as it would not seek to
home track without help. ran like that for several hours while I copied
it. It's internal airflow from the platters rotating were quite impressive.

Like I said in an earlier mail, all these drive have internal filters that
take advanatage of the airflow to capture any dust that makes it in.


Allison
Received on Sat Jul 11 1998 - 22:10:59 BST