[comp.sys.cbm] Need help fixing Blue Chip Disk Drive

miker@orca.WV.TEK.COM (Mike Reiney) (10/05/89)

I need help fixing my Blue Chip model BCD/5.25 Disk Drive for the C64.  
The stepper motor that drives the head in and out is not moving.

If I manually position the head to track 18 and initialize the
drive, it responds OK.  If I move the head one way or the other,
the 4-phase stepper drive pulses try to reposition the head.
The pulses go into the big chip on the analog board (MEL9501-40)
but nothing comes out to drive the motor.

Is there some sensor signal that's inhibiting the output?
Where can I get a new chip?  I'm told Blue Chip is out of business.
Can anyone supply a schematic for the drive?  Functional diagram of
the chip?
The only identifier on the drive is MEL.  That corresponds to the
number on the chip.  Who is that? Address?
Thanks for your help, miker