Somewhat OT - can underpowered power supplies damage a system?
gene.heskett at gmail.com
Thu Aug 19 06:38:29 UTC 2010
On Thursday, August 19, 2010 02:27:03 am Tim did opine:
> On Wed, 2010-08-18 at 13:38 -0400, Gene Heskett wrote:
> > Subtly mixed in with this might be a longer than normal spinup time at
> > powerup, leading to higher head wear in the first turn or two of the
> > spinup,
> I wouldn't have thought that would happen. The heads don't touch the
> drive in operation, and I thought parking the heads moved the arm
> completely off the disc.
It's been a while since they have been parked off disk. None of the drives
I have opened up in the last decade did anything but park them at a non-
data bearing location on the disk. This can often be identified by a thin
line of slightly higher polish on the surface. They use very little
pressure these days, and with decent brakes, usually by shorting the drive
motor when stopping, the time the head actually touches the disk is very
short, likewise when spinning up, the head takes off and flies at a safe
altitude before the disk has made a full turn. The heads fly in the 'ground
effect', with contours such that the faster the disk turns, carrying the air
with it, the closer to the disk the airflow pushes them, which when balanced
against the ground effect, results in a very consistent head flying height of
a very few microns.
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