[linux-dvb] Re: Help with J2 RGB

[Ragnar Sundblad <ragge@nada.kth.se>]

--On den 29 april 2004 20:05 +1000 Michal Dobrzynski 
<michal_dobrzynski@mac.com> wrote:

> 10. About 40 hours ago I started to attempt to make my own J2 to SCART
> socket. Destroyed a perfectly good (and unique) VGA cable based on tips
> on here. The entire cable is shielded (is this ground?) with the R, G and
> B wires independently shielded (is this R, G and B ground?).
Unique VGA cable - if you needed it, why did you use it for this? :-)

The shield is only ground if you connect it to ground, but that
is normally a good idea.

> At the J2 end I connected the ground to the shielding and each of the RGB
> grounds to the shielding also. At the SCART end I connected a 75 Ohm
> resistor between R, G and B and between their respective shielding (all
> connected to ground at J2). R, G and B as well as the composite sync
> signal and left and right audio are connected from J2 to the SCART socket.
I think that if you don't use a buffer (amplifier), you should
rather serial terminate the signal, like so:

<J2>-----<75 ohm resistor>-----<cable>-----<scart connector>

I am not sure about this, comments are welcome!

This is also a common way to connect a buffer amplifier.

Also, as you hopefully know, you must be very very careful if
you don't use buffers, as these outputs seems to be very very
easy to fry if you for example happen to connect the signal
before the ground.

/ragge



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