Re: IIgs to arcade monitor experiment

[Warren Ernst <wernst@gmail.com>]

On Apr 22, 10:13 am, MdntTrain <j...@cimmeri.com> wrote:
> I'm my seemingly never-ending dallying with with IIgs video, I thought
> I'd try interfacing my IIgs to an analog 15khz 19" RGB Electrohome
> "Go7" arcade monitor I have here.. just to see how well it works (or
> not).
>
> I could use some insight on impedance matching and video signal level
> from you resident masters of electron manipulation.  :-)
>
> Here's the situation.
>
> The IIgs video has these output specs:
>   RGB:  1 Vpp @ 75 ohm impedance
>   Sync:  4 Vpp @ 2k impedance
>
> An arcade monitor (non VGA type) typically has these input specs:
>   RGB: 4 Vpp @ 5k impedance
>  Sync: 2 - 4 Vpp @ 35k impedance.
>
> Video: these numbers don't look well matched, and I'm not sure what to
> do about it yet.    If I connect the IIgs RGB directly to a higher
> impedance than 75, the signal voltages are higher.. not as high as
> 4V... but maybe enough for sufficient contrast.   However, does the
> IIgs video signal get screwed up somehow if I don't load it with 75
> ohms?
>
> Sync: looks like a better situation.. as the voltages start out in the
> right range.   I'm not sure but my guess here is that the 35k sync
> input impedance won't be a problem for signal integrity ... as either
> 2k or 35k are "high impedance" inputs.
>
> Any thoughts are greatly appreciated as always.
>
> JS

Ask the guys on rec.games.video.arcade.collecting (RGVAC for short).
They're a knowledgeable group.

-Warr