13 Apr
2010
13 Apr
'10
2:47 p.m.
On Tue, 13 Apr 2010, Tony Duell wrote:
I've had a look at the Memorex 112 manual on
Bitsavers. If your drive is
similar, you might bave big problems.
I believe the drives are very similar, but haven't had much time to peruse
the schematics yet.
The relay contact is part of a 4-pole relay used to
turn on the spindle
motor (the other 3 poles connect braking resistors ot the windings) The
10 Ohm (5W) resistor is the fred to the collector of a power transistor,
whcih is the pass transistor for a simple 12V regulator. The emitter of
that transistor is the output of the 12V regualtor and feeds a lot of
analuge circuitry.
My guess is that the transsitor is OK (but it would be worth checking) and
that you have something downstream of it that is drawing exceessive
current. It might be a shorted decoupling capacitor, it might be an IC.
And to make things worse there seem to be some custom analogue ICs in
this drive.
I'll keep my fingers crossed on that.
> The heads are not stuck. If I tip the drive, I
can watch them slide
> across the platter from their own weight. Should have mentioned before
> that this thing has a translucent plastic top :-).
>
RIght..The Model 112 is a stapepr motor positioned,
BTW. That is what I'd
expect in a low capacity, but large platter drive like this. The trackls
would be suufficiently wide that a stepper motor would be fine. You need
a voice coil positioner taking a servo signal from the disk if you have a
high tranck density, of course.
Ugh. I'm not sure what I was smoking when I claimed it was a voice-coil
positioner... It is indeed a stepper motor. Sorry about that!
Steve
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