Date   : Wed, 13 Apr 2005 20:47:03 +0100 (BST)
From   : Pete Turnbull <pete@...>
Subject: Re: Possible faulty disk drive

On Apr 13 2005, 19:34, John wrote:

> As the drive is used more (within the same session), performance
seems to
> improve, although disks seen as unreadable stay that way. The
readability of
> commercial disks seems much better. Heat related issue, perhaps.

It might be a problem with the head alignment.  If the drive refuses to
read disks written on another drive, but can read disks formatted on
itself, the problem is most likely alignment.

> My first question is this : If these disks have been stored in a
fairly dust
> free environment for 16 years, should they have deteriorated

No, not significantly, assuming they're not HD disks or otherwise of
the wrong type for the purpose.  I've got 25-year old disks that read
fine.

> and if so, is
> it likely the commercial disks would survive better

No.

> OR is this disk drive
> damaging my disks - I'm sure on the new disks that a worn track is
appearing
> around a third of the way in when these are being formatted and
general wear
> On the old disks... the drive is pretty noisy most of the time.

That sounds bad.  It's possible that the heads need cleaned.  This is
not often required on 5.25" drives, whose heads are normally
highly-polished ceramic; it used to be a problem with some older 8"
drives.  Following the era of 8" disks, where disks were often left in
drives for days, and some makes/models needed regular cleaning, a
number of 5.25" cleaning kits (usually a special disk that could be
impregnated with isopropyl alcohol) appeared on the market.  Most did
more harm than good.  However, if once a head picks up some oxide then
it tends to scrape more off each disk you try, and it should be cleaned
before you do any more damage.  Do not use anything sharp or abrasive.
 Isopropyl alcohol on a lint-free swab is best, and you can use a
dentist's mirror to see the upper head in a double-sided drive (on many
drives it is not possible to lift the upper head very far away from the
lower one without damage to the mounting).

You mention "new disks".  Are these "new disks" labelled as double
density (or perhaps single density, it won't matter which), or as High
Density?  HD disks will not work properly in SD/DD drives, because the
magnetic properties are very different.  Both SD and DD disks have a
coercivity of 300 Oersteds; HD disks have a coercivity of 600 Oersteds
and need a much higher write and erase current in the head.

> Second question : Would the drive motor benefit from any sort of
> lubrication?

Very unlikely.  And don't lubricate the slide rails, though you might
want to clean them, if they're reasonably accessible, and make sure
everything that moves, does so freely.

> Third question : Can I recover data from the disks if damaged? The
BBC
> appears to know there is data on the disk, can even see the catalogue
> sometimes, but is clearly struggling.

Once you scrape the oxide off, nothing will get the data back.

> Finally, should I cease and desist till I get my hands on another
drive
> rather than risk continuing with those few disks that DO work?

Definitely.  At the very least, use just one "scratch" disk for
testing.

Perhaps someone on the list can lend you another drive to try.  If not,
I'm sure many of us could volunteer to try reading one of your disks on
a known-good drive.

-- 
Pete                                           Peter Turnbull
                                               Network Manager
                                               University of York