[Coco] RGB2VGA DE0-Nano Programming Help - Pictures

[Steve Batson]

It is an awesome setup once everything is working. Roger Taylor's recommended resistor value changes really cleaned things up. On my system, I was experiencing some RF noise manifesting as slight rolling on the sides of the screens. It doesn't sound like others were seeing this. In any case, I built a second RGB2VGA card and that actually helped a bit. I then did some experimenting to try to narrow it down.

I was pretty sure that the noise was creeping in on the ribbon cable connecting the CoCo RGB port to the DE0-Nano.

First I put a very short ribbon cable (about 6 inches) in place of the 3 foot ribbon cable. This helped immensely.

Next I took the 3 foot ribbon cable and wrapped it in tin foil and the noise cleared up, everything is very clear, crisp, stable and without noise that I can see.

My conclusion is that at least in my case, a shielded cable is the cure. i'm not surprised as sending video over a ribbon cable with no shielding as Radio Shack designed really isn't the best choice and I'm sure was done for cost reasons. 

Anyway, the ribbon cable is working for now with my tinfoil solution, but I may modify a VGA cable replacing the connectors with header connectors and see how that works.



On Aug 1, 2015, at 5:59 PM, K. Pruitt <pruittk at roadrunner.com> wrote:

> Here's a couple pictures of pacdude on the CoCo 3:
> 
> The colors look much better in person.. Everything is very crisp whereas the camera added some blur.
> 
> https://www.dropbox.com/s/qzu90ogvphnsrok/DSC01548.JPG?dl=0
> 
> https://www.dropbox.com/s/uyrcm9slrnhh6gv/DSC01546.JPG?dl=0
> 
> 
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