[Coco] 4 Port MPI PCB artwork (so far)

[Gene Heskett]

On Sunday 08 March 2015 13:50:44 RETRO Innovations wrote:
> On 3/8/2015 1:57 AM, Gene Heskett wrote:
> >    * Determine if large PCBs with the angled "ears" will need slots
> > cut in the PCB to ensure full edge connector mating
> > Yes.
>
> Hmm, anyone have a pic of the MPI PCB?  Google can't find one...
>
> > I think the only real answer there is to cut out a board with them,
> > see how it is guided into the connector,  then cut them off and
> > check again. I've suspected that as long as the contact pad for the
> > clip on the socket to grab and ground is there on each side of the
> > finger pattern, that the slanted ear out wider than that was
> > probably optional.
>
> Fair enough, but it looks like Dragon users are SOL with the grounding
> pad.  How important is it?
Fairly Jim.  My 2nd generation MPI has a logic timing  glitch that 
results in a buss clash at turnaround time, and the resultant logic 
short creates a heck of a ground bounce, above a volt, for a fraction of 
a microsecond, which in turn has led to some data corruption.  With the 
pads clean and socketed into the clips, some solder braid short 
circuiting some of the more distant reachs on the ground plane to a 
better ground, and about .1 uf of extra rail bypassing, it works now.

I also have a 26-3124, which I should instrument and check, but keep 
miss-laying my round tuit.  And the next 2-3 days will be spent sinking 
a sump in the poured basement floor, and rigging an automatic sump pump 
to at least try to lower the water table to a point below the basement 
floor.

So not a lot of coco related work will be done until I can hear that pump 
cycling in the wee hours of the night.  Among other things, the rug 
under the coco's desk is soaked.   We can't have that can we?

> JIm

Cheers, Gene Heskett
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