Re: Disk ][ Drives not working

["John B. Matthews" <nospam@nospam.com>]

In article <6c6dnRaHjfvu63jdRVn-tw@comcast.com>,
 "Bill Garber" <willy46pa@comcast DOT net> wrote:

[...]

> I too use DD disks in Disk II drives, no problem.
> Recently I had plugged a Disk II onto the card in the
> machine and got the first row of holes of the plug on
> the second row of pins as such:
> 
>   |===================|  Card edge
>   |o o o o o o o o o o|  Row of pins
>   |HHHHHHHHHHHHHHHHHHH|  Plug on Pins
>   |HHHHHHHHHHHHHHHHHHH|  Plug not on pins
> 
> After doing so and powering up and down again
> my Disk II responded as does the drive that is
> being described in this thread. It will seek
> track zero, but do no more. I suspect that the
> IC "ULN2003" is the culprit. I haven't had the
> opportunity to mess with it yet, but when I do
> I will post my results.

This is an excellent picture of a well-known way to fry the 
analog card inside the drive. I seem to recall folks saying it 
blew the "read sense amplifier" chip, luridly recounting how it 
would smoke and be visibly burned afterward. Is that the 
"ULN2003" you mention?

[...]

John
----
jmatthews at wright dot edu
www dot wright dot edu/~john.matthews/