Re: IIgs RGB to YPbPr Component experiment

[Roger Johnstone <news2006@roger.geek.nz>]

In <1152203470.245771.95150@m73g2000cwd.googlegroups.com> jsnospam@
cimmeri.com wrote:
> 
> Note to Roger Johnstone:
> 
>    For the above test, I modified your cable by removing all audio
> signals (just my preference), and removing the function select.
> 
>   I also used the IIgs pin 12 composite video -> Scart 20, instead of
> pin 3->20.   Not sure of any advantage or disadvantage to doing this...
> performed the mod when trying to figure out why the SCART input
> wouldn't come on.  Later discovered the need for a non-USA country
> setting (stupid!)... but kept 12->20 intact.   Works fine so I'll 
> leave it alone.

Hey, if it works leave it.

Background for everyone else: SCART pin 20 is the composite video input. 
When you use the SCART's RGB inputs pin 20 becomes the sync input. 
Composite video has the sync signals in it, so normally it doesn't 
matter if you feed a full composite video signal to pin 20 or just a 
sync signal.


>   I also lifted the shield ground at the IIgs side.   Some debate on
> this, but in audio at least, we never pass ground through from chassis
> to chassis to avoid ground loops... especially when another ground is
> already being passed through (Red Ground).

That's a good point. A lot of cables connect the shield straight through, 
but it's often better not to.


-- 
* Roger Johnstone, Invercargill, New Zealand -> http://roger.geek.nz
* PS/2 Mouse Adapter for vintage Apple II or Mac
* SCART RGB cable for Apple IIGS