23 Oct
2015
23 Oct
'15
9:31 a.m.
The 2190 does not, and it fails in precisely the
same way I've personally seen three or four
other Maxtor drives of the same era fail: It spins up fine, but when it goes to load the
heads,
it sounds like the voice coil positioner for the heads is "screaming" -- it
emits a high-pitched,
quite loud whine/buzz which persists until you power the drive down. The drive is
unresponsive
during this time.
Sounds like a failure of the positioner servo. It is on a separate platter.
I wonder if there is a separate velocity feedback coil (not unuheard-of, but not that
common on
smaller dries)? If so, a problem with that would cause the servo to go unstable.
Normally a total loss of servo information causes the heads to hit one or other of the end
stops,
but there are many other posibilities.
It should be possible to build something to open the
servo loop and position the heads
externally. One of those projects that I would like to get to some day. I have about 50
Remember that in the end all you can control is the current through the 'motor'
coil (not
strictly a voice coil in this drive, but the same idea), and that applies a force
(==acceleration)
to the heads. Normally this is a closed loop system, signals picked up by the servo heads
tell the control electronics of the heads are off-track (and basically how far) this is
used
to generate a correction signal to feed to the coil.
If you open the servo loop, you will be able to accelerate the heads but little more. You
will
not AFAIK be able to keep them on track.
Of course the other issue is that if the servo head/platter/preamp is malfunctioning, will
the
data heads be any better? You may not be able to read anything much even if you are
on-track.
-tony