31 Oct
2009
31 Oct
'09
6:03 p.m.
On Sat, 31 Oct 2009, Steven Hirsch wrote:
I just purchased one of these on ebay, but am unable
to find even a shred of
documentation on the web.
It's equipped with a "PC" style 4-pin Molex connector for power, unlike the
more usual 6-pin square connector used by all my other 8" drives. What I'd
like to confirm is whether this unit can actually run on 12VDC. It does not
seem to work correctly with 12V applied, which could suggest either that it
requires 24V or is defective.
Before I let the magic smoke out of it, does anyone know the proper voltages
for this drive?
Some empirical evidence:
- The unit has a 7812 (12V) 3-terminal regulator hung off what would
normally be the +12V line of the molex connector for, e.g. a 5.25" floppy
drive. That input goes through a 100ohm 5W resistor before hitting the
regulator. With 12V applied the drive, I see only 9.2V at the input to
the regulator and approx. 7V on the other side. Sure _looks_ like maybe
it's supposed to see +24V at the top of that resistor, doesn't it?
- With 12V applied, the head-load solenoid doesn't reliably pull in on its
own.
- Head stepper seems a bit anemic.
- I can hear the drive motor slow down from the drag when the heads are
loaded.
- Drive goes through some motions of writing, but won't verify or read
anything.
How luck should I feel? Should I apply +24V and keep my fingers crossed?
Anyone have one of these drives installed and be able to put a voltmeter
on it?
Steve
--