[Coco] Idea: CoCo tray

[Gene Heskett]

On Sunday 22 October 2006 15:10, Jim Cox wrote:
>I was thinking of a way that I could secure my CoCo 3 to
>the MPI so that a bump when they are on wouldn't turn them
>into bricks and came up with a idea.
>
>I like the idea of the locking plates and will use the one
>I have for a permanent set up, but right now, I am
>constantly opening my CoCo to look around as wells a
>moving it around, so I don't have the plate installed.
>
>What I was thinking for cases where using a locking plate
>isn't practical, is to make a tray out of plywood with
>some smaller 1"X1" blocks in the corners and sides, so
>that the CoCo and MPI could just fit on the tray and would
>be secure enough to prevent bumps from damaging them.  It
>would also make moving the CoCo and MPI around much
>easier.
>
>Has anyone tried this?  I'm thinking of making one of
>these, but I am not a carpender.  Are there some good
>carpentry rules I should follow with regards to measuring
>the tray out?
>
>-Jim

I think its a semi-decent idea Jim.  But I'd toss in a caveat too.

The std mpi doesn't have gold plated fingers, so called solder-plated is 
what was used.  It actually needs a certain amount of wiggle exersize to 
keep making good connections, which works for 6 months to a year after 
which I had to mechanically polish off the dark lead oxide coating on the 
finger pattern again. I even replaced the solder film on mine due to bad 
connections many times, and eventually had my fill of that little 
operation.  Life is too short to screw with that hassle IMO.

So I hunted around in my junk box till I found an old ISA pc card that was 
gold plated.  I sawed off enough contacts to match the coco's count, about 
3/8" back from the edge, which wasn't far enough in this case to get rid 
of all the internal shorts due to its being a multi-layer board.  So it 
got shortened a few thou at a time, rechecking for shorts after each pass 
across the grinder wheel.  It was finally clean, no shorts when it was at 
about 5/16".

Then I sawed about 1/4" off the mpi's board and filed the edge till it was 
as straight as the piece from the above paragraph, fitting it till there 
was just a barely discernable crack when the two pieces were held 
together.  Then I taped them together on one face so I could put a drop of 
some special hi-tensile solder I have which has a quite high silver 
content across each break in the copper pattern, then turned it over, 
removed the tape and did the other side.

It has been absolutely bulletproof for about 15 years now.  So I think I 
might be able to bolt it down solid now, but somehow never quite got that 
famous round tuit.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Yahoo.com and AOL/TW attorneys please note, additions to the above
message by Gene Heskett are:
Copyright 2006 by Maurice Eugene Heskett, all rights reserved.