[Coco] COCO3 Video

[David Ladd]

Also I would like to add my 2 cents worth here as well.

There is another big thing you need to check when dealing with RGB hardware
is what the output voltage from the RGB lines are.  For example the CoCo
3's voltage output at full RED, GREEN, BLUE, the max voltage output will be
2 Volts.

Now SCART spec is 1 Volt on the RGB lines.  So when taking a CoCo 3's RGB
line's to the SCART lines you need a 150 to 180 Ohm resistor and
electrolytic capacitor in series to bring the voltage down to a safer level
for the SCART input.

I used:
http://members.optusnet.com.au/eviltim/gamescart/gamescart.htm

As a reference to some of the testing to figure out why the original CoCo 3
RGB to SCART cable was so over powered.

The negative lead of capacitor goes towards the SCART and the positive side
goes to the resistor.  Then the other end of the resistor goes to RGB out
of the CoCo 3.  So you would need 3 pairs of these...  1 pair for each
color analog line.

I hope that makes sense.



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| David Ladd a.k.a. PacoOtaktay a.k.a. Drencor                          |
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| Do you have your CoCo 3 yet?                                          |
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On Thu, Mar 1, 2018 at 12:45 PM, Zippster <zippster278 at gmail.com> wrote:

> Not really a standard, but does denote RGB and separate (H)sync and
> (V)sync.
>
> The CoCo3 outputs 15.7KHz analog RGB with separate, positive-going syncs.
>
> I’m guessing the boards you mention are the GBS8200 and similar scan rate
> doublers
> to get VGA scan rates.  They’re cheap, they work, and they’re generally
> considered a little fuzzy.
>
> Other options are available like the super espectro from cloud9 and
> Richard Lorbieski’s SCART
> to HDMI cables that will give a much better picture.  Still, has to beat
> RF and composite, right?  :)
>
> - Ed
>
>
> > On Mar 1, 2018, at 12:15 PM, Bill Gunshannon <
> bill.gunshannon at hotmail.com> wrote:
> >
> >
> > I am just full of questions today.  :-)
> >
> >
> > There is apparently a standard (of sorts) called RGBHV.
> >
> > I think it was used in video games although there does
> >
> > seem to have been some attempt to get it into the home
> >
> > theater market.
> >
> > My questions:
> >
> > Anybody here familiar with it?
> >
> > is it likely that the output from the bottom of my COCO3 would match
> > this spec?
> >
> > My reason for asking is I have a board that claims to be able to convert
> > this to
> >
> > VGA.  If it were to work, these boards are really cheap ands still seem
> > to be
> >
> > available all over the web.
> >
> >
> > Given no information I amy give it a try, but I will have to make a
> > cable and
> >
> > that may be more work than I can easily do as I expect those DB15's are
> >
> > rather crowded.
> >
> > bill
> >
> >
> >
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco
>
>
> --
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>