Deep fried inductor...

[Tony Duell]

> On the Siemens drives also used in the H89 and H17, there is an inductor
> in series with the +12 to the spindle motor.  It's a hash choke that keeps
> the motor noise from going back into the +12 rail.   When the grease in
> the spindle motor gets old and sticky, the motor draws way too much current
> at startup (if it ever does start spinning) and toasts this inductor.

If this is the Siemens drive used in the Z90, I have the schematics here 
(io the Z90 hardware manuals). I can't see an 'L5' at all, but the drive 
I have has a separate motor control PCB with a series choke (but a 10uH 
one) in the supply line. It's easily posible that later drives put 
everything on one PCB (as Tandon did).

-tony