[Coco] Composite Video Mod for CoCo1

[Luis Antoniosi]

I got this quality using a very good coax cable connected direct to
the coco2's RF out (using a F to coax adapter) and plugging on LCD TV
cable in (no switch box between)

https://twitter.com/RetroCanada76/status/260950375606124544/photo/1
https://twitter.com/RetroCanada76/status/260949208633323522/photo/1
https://twitter.com/RetroCanada76/status/261807864576884737/photo/1
https://twitter.com/RetroCanada76/status/260948976143044608/photo/1
https://twitter.com/RetroCanada76/status/260950612127133696/photo/1

I have very similar results on Coco3's RF output too:

https://twitter.com/RetroCanada76/status/256045981202800640/photo/1

But I noticed my coco3 composite is not better than the RF i'm getting
using this cable. Here is the cable/connector on my coco3:

https://twitter.com/RetroCanada76/status/256046189722628096/photo/1


I noticed too when the coco2 is on blue/red instead of red/blue scheme
the characters on 32 column screen are crispier. I can detect right
way after the boot which fake "color palette" it is using. :)



On Thu, Dec 6, 2012 at 9:08 AM, Brian Blake <random.rodder at gmail.com> wrote:
>
> 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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>
>
>
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