[Coco] Composite Video Mod for CoCo1

[Brian Blake]

Daniel,

Very impressive results indeed. Never seen video that crisp and clear on 
a CoCo1 or clone.


Brian

On 12/6/2012 8:07 AM, Daniel Campos wrote:
> Hi Fedor,
>
> Yes, I saw your post some time ago but the hand written schematics are
> not so clear to understand. For the pictures, I can guess that some
> wireup got loose on transport.
>
> I just have done the mod described on the MC6847 datasheet, and after
> a fine tunning using trimpots, a believe I came with a good overall
> image. The pictures bellow, shown the final result on my Color64:
>
> https://picasaweb.google.com/109345699838454178536/LZColor64#5818574442902576802
>
> https://picasaweb.google.com/109345699838454178536/LZColor64#5818574744878407410
>
> https://picasaweb.google.com/109345699838454178536/LZColor64#5818575311739711346
>
> https://picasaweb.google.com/109345699838454178536/LZColor64#5818575226684298914
>
> https://picasaweb.google.com/109345699838454178536/LZColor64#5818574448002174674
>
> https://picasaweb.google.com/109345699838454178536/LZColor64#5818574792157143906
>
> https://picasaweb.google.com/109345699838454178536/LZColor64#5818574797580859266
>
> https://picasaweb.google.com/109345699838454178536/LZColor64#5818575156296252562
>
>
> Tweaking the trimpots yesterday I came with a good improve on contrast
> since those pictures were taken.
>
> Thanks,
> Daniel
>
>
> 2012/12/6 Fedor Steeman <petrander at gmail.com>:
>> Hi Daniel,
>>
>> If you search the list, you can read that I posted about this subject a few
>> times already earlier.
>>
>> In short, I acquired a CoCo2 with such a composite video mod that worked
>> fine, until I transported it somewhere at a certain moment. I think
>> something came loose or short-circuited, because now I only get a black
>> screen. It can probably easily be fixed, but I am not that skilled enough to
>> do it.
>>
>> The video mod is based on the following manual (in Dutch):
>> http://www.steeman.dk/CoCoManuals/VideoMod_(KoenVaartjes).pdf
>>
>> Here are some pictures of it:
>> https://picasaweb.google.com/115146243402896969496/CoCoVideoMod?authuser=0&authkey=Gv1sRgCKCWiaq64ompugE&feat=directlink
>>
>> Cheers,
>> Fedor
>>
>> On 3 December 2012 13:48, Daniel Campos <daniel.campus at gmail.com> wrote:
>>> Hello,
>>>
>>> Since I got the Color64 (Coco1 clone) his image, even already having a
>>> composite video output, have always disturbed me with a crap image
>>> compared to other CoCo machines. So I began to try to correct that and
>>> removed the entire transcoder analog pcb that came with the computer
>>> and used the schematic bellow to try to have a better composite
>>> output:
>>>
>>> http://www.victortrucco.com/Diversos/MC1000/SaidaAV.JPG
>>>
>>> The schematic above is largelly based on the driver for color
>>> composite video that is showed on the 6847 datasheet. After build the
>>> mod, image is great on text mode, sharp and crispy, the problem begans
>>> when I got to the graphics mode using artifacting. For example, on
>>> Outhouse, the initial screen should be red, but appears with a very
>>> pink saturated color, it's impossible to read. Other games, like
>>> Draconian and Galagon got very saturated too.
>>>
>>> My question is, someone here have done any of the scematics bellow and
>>> worked fine on a LCD monitor with composite video ?
>>>
>>>
>>> http://www.retrocomputers.eu/wiki/index.php/Tandy_TRS-80_Color_Computer_(CoCo)_Composite_Video_Mod
>>>
>>>
>>> http://sd2cx1.webring.org/l/rd?ring=coco;id=1;url=http%3A%2F%2Fwebspace%2Ewebring%2Ecom%2Fpeople%2Fvt%2Ftheother_bob%2Fcoco_page%2Fccprojects%2Ehtm
>>>
>>> Any suggestion would be higly appreciated. :)
>>>
>>> Thanks,
>>> Daniel
>>>
>>> --
>>> Coco mailing list
>>> Coco at maltedmedia.com
>>> http://five.pairlist.net/mailman/listinfo/coco
>>
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