[Coco] composite / s-video to hdmi

[Daniel Campos]

Here in Brazil we have two LCD monitors that accept 15Khz through the
VGA connector. They are the Samsung 510n and LG M1721a, this last even
has RF, composite and Svideo input. Bellow are the excelent reviews
done by Victor Trucco:

http://www.victortrucco.com/Diversos/Monitor510N/Monitor510N.asp

http://www.victortrucco.com/Diversos/MonitorM1921A/MonitorM1921A.asp


But Coco3 has a inverted sync on his RGB output (positive instead of
negative), so it has to be modified internally to work with those
monitors. Bellow are the mod done on Juan`s Coco3:

http://www.victortrucco.com/Diversos/ConsertoCoco3/ConsertoCoco3.asp

Daniel


2012/12/17 John E. Malmberg <wb8tyw at qsl.net>:
> On 12/16/2012 11:48 PM, Gene Heskett wrote:
>>
>> On Monday 17 December 2012 00:26:02 John E. Malmberg did opine:
>>
>>> Which means that they can handle the 15.75 NTSC time signal.
>>
>>
>> Thru the composite jack?  Have you ever tried to read the coco3's 80
>> column
>> screen thru a composite hookup, or on an ntsc tv?  Difficult if not near
>> impossible.  The bandwidth in the NTSC circuit simply is not there.
>
>
> No, through the SVGA jack.
>
>>> There are reports that the COCO 3 could work with Multi-sync monitors if
>>> they supported 15.75 Khz sync, and I previously posted a link.
>>
>>
>>> And all the flat screen TVs that I have come with an SVGA connector.
>>
>>
>> Which, with Chris Hawks adapter, should work noticeably better than any
>> composite setup, whether direct composite or rf modulated composite.
>
>
> If the TV supports 15.75 Khz, then it probably supports it through the SVGA
> jack.
>
> The reason it was scarce in computer monitors is that it required a more
> expensive flyback circuit.
>
> But as you know, there is no flyback circuit in modern LCD TVs.  So no real
> reason for the multi-sync circuit to not support 15.75 Khz from any the
> sources on the TV.
>
> Now this also may be something that works in most TVs and not others. It
> just may depend on what is cheaper, having the multi-sync circuit work down
> to NTSC frequencies or having to double the NTSC lines from the composite
> video stream.  My guess would be not having the doubler circuit would be
> cheaper.
>
>>> Unfortunately my COCOs are still boxed up, so I have not been able to
>>> try it a SVGA to COCO cable to see if it just works.
>>>
>> Don't forget John, that I am a broadcast engineer, who has been making
>> sure
>> there was a picture there when you turned on the tv, from 1962 to 2002, 40
>> years.
>
>
> I only did the broadcast engineering for my last year of college, about 1981
> to 1982.  To give you a hint as to where, along with the TV transmitter at
> the site I was at, there also was the most powerful commercial FM
> transmitter in the U.S.
>
> Regards,
> -John
>
>
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