Dead IMI-drive (was Re: Onyx C8000: good news and bad news as well)

[Tony Duell]

> 
> > >The IMI 7020 hard drive is dead and cannot be fixed:
> > >The damn coil of the motor causes a short circuit   :(
> >=20
> > I'm sure you checked, but possibly could it be motor braking electronic=
> s or=20
> > the good old reversed diode across the windings that have shorted, and =
> not=20
> > the motor coil itself?
> 
> This reversed diode sits on a small PCB outside the motor. =20
> I disconnected it, having the two wires of the 24V DC Motor in my hands.

How many wires does this motoe have in total? If quite a few (6 or more), 
then I would suspect a motor with electronic commutation on one of the 
drive PCBs, and it's quite common for the windings of those motors to 
have very low DC resistances (< 1 ohm). 

If there are only 2 wires, presumably power connections, I would still 
suspect an electronically commutated motor (you need to keep the speed 
pretty constant after all). It's possible there's some circuitry inside 
the motor, and perhaps a trnasistor has gone short-circuit or something. 
Can you get inside the motor at all without opening the HDA? (I know it's 
possible to remove the winding assembly from the motor on a Micropolis 
1200 in the field, but it does need special tools...)

-tony