[Coco] CoCo 2 Factory Composite Video RE'd

[Zippster]

I know you can tap, invert, and amplify the Luma signal for a monochrome display.
Two transistors and a few resistors, and three leads, Luma, +5v, and ground.

The Y output from the 6847 is an inverted Luma with composite sync.

- Ed


> On Dec 15, 2014, at 1:05 PM, Bruce W. Calkins <brucewcalkins at charter.net> wrote:
> 
> I have a simple monochrome driver in one of my CoCo 2s that is "clipped/tack soldered" in.  As I remember it the color version was somewhat more complicated and I did not persue that route then.
> Bruce W.
> =================
> 
> ----- Original Message ----- From: "Zippster"
> 
>> From what I’ve read, my understanding is that the CoCo1 did generate a composite signal that could be tapped
>> before it went to the RF modulator, but that the CoCo2’s used the 1372 differently, going directly to RF
>> and didn’t have a valid composite signal that could be tapped directly (except for Luma maybe).
>> 
>> I think those CoCo2 “video driver boards" were picking up the various signals and then generating the composite signal.
>> 
>> A clipped in adapter could easily be done, but I’d much rather have something soldered in.
>> 
>> - Ed
>> 
>>> On Dec 15, 2014, at 11:19 AM, Bruce W. Calkins <brucewcalkins at charter.net> wrote:
>>> 
>>> Be advised that the modulators are different in the CoCo 1.  For one thing the MC-1372 is on the motherboard and not in the RF modulator.  My CoCo 1 composite monitor driver simply clipped to several points on the motherboard.  FWIW; it looks to me that you have complicated a simple task. "Back in the day" even the CoCo 2 composite monitor drivers simply clipped in, the rub being that the RF modulator needed to be opened to access the MC-1372.
>>> Bruce W.
>>> ==================
>>> 
>>> 
>>> ----- Original Message ----- From: "Zippster"
>>> 
>>>> I can layout boards to replace any of the RF modulators if I know the dimensions and pinouts.
>>>> 
>>>> So far I know of 3 types, CoCo 2 - Korean motherboards (RF lays flat on MB), earlier (pre-Korean?)
>>>> motherboards where the modulator is larger, and on edge.  And then CoCo1 (all the same modulator?)
>>>> 
>>>> I have no problem doing boards for all these types if people want them.
>>>> 
>>>> - Ed
>>> 
>>> 
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