Re: Disk ][ Drives not working

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

In article <2I2dnZAtL_y-F3jdRVn-gw@comcast.com>,
 "Bill Garber" <willy46pa@comcast DOT net> wrote:

> "Bill Garber" <willy46pa@comcast DOT net> wrote in message
> xKOdnVLo-pY-G3jdRVn_iw@comcast.com">news:xKOdnVLo-pY-G3jdRVn_iw@comcast.com...
> :
> : "John B. Matthews" <nospam@nospam.com> wrote in message
> :
> news:nospam-412BD7.11523702072004@news-server-fe-02.columbus.rr.c
> : om...
> : : 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?
> :
> : I'm not sure if that is the "read sense amp", but
> : it is the chip most commonly known to go first when
> : plugging it in that way. I'll see if I can find the FAQ
> : and post the paragraph on that, or the link if it's too
> : much to post.  :o)  Maybe someone with more time could
> : help me out on this.  :o)
> 
> Here is the link to the Disk II misaligned connector
> problem and fix. It's not much, but it's a start.
> 
> http://home.swbell.net/rubywand/Csa2FDRIVE.html#012

I should have started with the FAQ:-)

I see now that the read amplifier is MC3470

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