[Coco] Strange video issue

[Zippster]

Signal level/proportions are off.  That circuit (Darlington pair with a decoupling cap) doesn’t allow for any adjustment.
It also may not help that the CoCo 1 doesn’t have a color burst generation circuit.

Redesign the circuit to allow for amplitude adjustment and proportion of sync to active video?

Hard to get more specific without putting a scope on it.  The way it’s coupled through a 22Ω resistor kind
of makes me wonder what kind of receiving circuitry they were expecting on the other end...

Can you compensate with the tint controls on your TV?

- Ed


> On Sep 7, 2015, at 7:29 PM, Barry Nelson <barry.nelson at amobiledevice.com> wrote:
> 
> I built this circuit and installed it in my CoCo 1. 
> 
> http://www.cocopedia.com/wiki/index.php/File:Trs80coco2compmod.gif
> 
> It mostly works, except for pmode 4… On a pmode 4 screen, what should be blue shows up as greenish turquoise, and what should be reddish orange is instead reddish purple. Any idea why or how to fix it? Otherwise the video is ok on most other screens.
>