[Coco] CoCo 3 to RBG...

[gene heskett]

On Wednesday, July 20, 2011 04:34:58 PM Steve Batson did opine:

> Gene,
> 
> I didn't even see that about on board connector only handling
> 31Khz...Ok, well it looks like I need to go with my original plan and
> build the ribbon with a 15 Pin D connector. Not too excited about that
> due to the very small amount of space to work in on the connector. I'm
> almost tempted to build some type of small project board where I can
> mount connectors to the board and do all the crosswiring on it, seal it
> up in a box and then be able to use standard, straight through Ribbon
> cable on the coco side and standard straight through VGA cable on the
> output. I couldn't find my soldering iron, so I ordered one last
> week...should be her this week along with a 15pin D connector. I just
> picked up a VGA cable the other day for about $5, but it doesn't look
> like I'll need it, so I'm seriously thinking about just cutting it and
> splicing it to the ribbon cable from the Coco. At this point, I want to
> see it working before I invest any time or more money in making it
> pretty.
> 
I went back, fired up my magnifying lamp, and re-read it a few more times.  
The 8 pin connector behind the DB15 (P10) is P11, the EGA/CGA 5 pin is P3, 
and the text says 15khz and up for P3, P10 and P11.  That then tells me I 
miss-remembered it, and that the 8 pin connector should work.

Then on checking fit, it's too big to fit it internally to a coco3 with a 2 
meg kit in it, then its also too big front to rear to fit in the right rear 
corner of the upper case even w/o the 2 meg kits buffer pcb.  So I grabbed 
a white ash plank about .125" thick that was planed smooth on one side, and 
ripped it up to make a couple slices of bread to make a sandwich with the 
board in the middle.  An 1/8" tall standoff under the board, and a 3/4 
above the board should space it about right.  I cut a notch in the top of 
to get to the pushbuttons, but I will probably mount it and adjust the pots 
if needed & then cover them up.

The remaining question you may be able to answer & has to do with how hot 
that chip with the heat sink glued to it gets.  In other words, do I need 
to drill some vent holes in the cover right over the heat sink?  I intend 
to cut some thin alu and see that its grounded through the board mount 
screws to reduce the ingress/egress of digital noise before its assembled 
for the final time.

Some of the foil & plastic stuff the shack covered the bottoms of the pcb's 
with would be just the ticket but I'm not tearing up another of my coco's 
to get it and I have never seen the stuff for sale.

Cheers, gene
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