Wayne Stewart wrote:
It's definitely a problem on the Disk II card. After the first ULN2003 blew, I just replaced the chip and promptly fried it too. At that point I wondered if it was the drive or the card so I dug out one of each. A new drive connected to the old card promptly blew it's ULN2003 too. After replacing the ULN2003s both drives functioned normally with the new card.
The 9334 on the controller card drives the phase signals. -michael NadaNet and AppleCrate II: parallel computing for Apple II computers! Home page: http://home.comcast.net/~mjmahon "The wastebasket is our most important design tool--and it's seriously underused."