[Coco] 26-3029 Disk Controller compatibility & repair??

[Arthur Flexser]

It was the original 26-3022 controller that had a WD1793  requiring 12V.
The 26-3029 does not, whether it has the original WD1773 (?) or the
replacement MB8877A.

Art

On Wed, Jan 21, 2015 at 12:23 AM, Chad H <chadbh74 at hotmail.com> wrote:

> I just acquired one of these controllers, the early model with the  MB8877A
> controller insteadof the WD1779.  The first thing I did was plug it into my
> CoCo2 and it did boot Disk BASIC and controlled my drives but seemed a bit
> unreliable.  I had to play with the ribbon connector.  I suspected dirty
> card edge but I found contradictory information online concerning this
> cartridge.  Some sites say it was +12V only and therefore not compatible
> with the CoCo 2 with a MPI, other sites say it's +5V so should have no
> problems.which is it?
>
>
>
> The screw seal had already been broken so I went ahead and took it apart
> and
> some of the chips, especially that  MB8877A, had rusted pins. Both card
> edge
> connectors were dirty as hell. I tried cleaning where possible and
> removing
> what could be removed but in the process I damaged a couple of the legs
> from
> the controller chip and they broke.  I tried soldering on 'extensions but
> the flux was fighting the oxidized remnants of the pins and by the time I
> got it to stick, I think I might have damaged the MB8877A from solder heat.
> Now it attempts to access the correct drive with motor on and light on, but
> I don't hear any head movement and after a few moments all I get is "I/O
> ERROR" in DECB.  Fortunately these chips still seem to be available
> relatively cheap so I ordered one from china for $4.75.
>
>
>
> Could someone please confirm if this controller is indeed  +5V only
> controller so it will work with my CoCo 2 as I don't have a MPI.  Also, for
> you guys that have had to clean very dirty card edge connectors, what do
> you
> find to be the best cleaning techniques?  Thanks!
>
>
>
> -         Chad
>
>
>
>
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