Re: Hacking the Apple II Disk Drive!

[shoppa@alph02.triumf.ca (Tim Shoppa)]

In article <3271811b.990366@news.polaristel.net>,
Tim Gerla <timg@climax.polaristel.net> wrote:
>I just dismantled an original Apple II disk drive, got the nice
>looking stepper motor out, and what I believe is the stepper driver.
>It's a small board, about 4"x1". It's got a few assorted caps,
>resistors, and two crystals, a SIP IC, and a green TO-220 thing. It's
>got six output pins, but only three of them were connected. The
>stepper has six wires. Does anyone know anything about how to run it?
>Is that board actually the stepper driver? Any info would be helpful!
>Thanks!

The stepper driver in the Apple Disk ][ is the ULN2003 chip
on the large ("top") circuit board.

The 4"x1" board in a Disk ][ is the motor speed control
board.  You say it's got two crystals, though.  Except for this
detail, it sounds very much like the speed control board
I've seen in all Disk ]['s (and the same as used in a more
vanilla Shugart SA390/400, I think.)

Are you sure you're taking apart a real Disk ][?  None of the ones
I ever worked on had crystals inside of them - and I've repaired
literally hundreds.  Your confusion about not being able to identify
the stepper motor driver (it's obvious IMHO - just trace the circuit!)
would lead me to believe that you may be working with a very different
beast.

Tim. (shoppa@triumf.ca)