SNES RGB scart cable

[MKL]

I'm bulding a custom RGB scart cable for a PAL system. It will use a HD15 connector that I have already installed in the back of the console. So now I have to hardwire the relevant pins of the proprietary A/V connector and run them to the custom HD15 out.

The A/V pinouts of a PAL systems should be as follows:

1.Red analog video out (1vpp video into 75 ohms)
2.Green analog video out (1vpp video into 75 ohms)
3.+11V DC
4.Blue analog video out (1vpp video into 75 ohms)
5.Ground
6.Ground
7.Y (luminance) signal for S-VHS (1vpp into 75 ohms)
8.C (chroma) signal for S-VHS (.3vpp into 75 ohms)
9.PAL composite video signal (1vpp into 75 ohms)
10.+5v (provides power)
11.Left channel audio out
12.Right channel audio out

On the N64/SNES pinouts page I read: "PAL users note: A PAL SNES outputs +11v on pin 3, not composite Sync. This is for a SCART TV to automatically detect RGB input."

1) Now if pin 3 is not composite sync as on NTSC systems but +11VDC, what is it supposed to be used as sync? Pin 9 (composite video) I assume, although it's odd that there's no dedicated sync pin.

2) I don't see how the 11v on pin 3 could be used to switch to RGB mode: that is done by supplying 1-3v to scart pin 16 (blanking) and that voltage is taken from the SNES pin 10 (+5v) with a (~100ohm) resistor in between. The only case where you could supply a scart pin as high a voltage as 11v is on pin 8, that needs 9.5-12v to select a 4:3 aspect ratio and this is not even necessary on non-widescreen TVs (and widescreen was far from popular when the SNES was released which adds to the mystery). My idea is to just ignore the 11v pin, although I find it odd that it was specifically implemented on PAL machines...any thoughts?

On the N64/SNES pinouts page I also read: "As seen below, the SNES does have RGB capability [...] The DC offset needs to be filtered out with some large capacitors and the peak-to-peak video amplitude may need to be reduced to 0.7v by using a lower load impedance than 75 ohms".

So by default the RGB is 1v pp while the scart standard requires 0.7v pp. However, I've read in some thread here that cables that have caps in the RGB lines aren't good for PAL machines and I could see this myself when I hooked up the SNES with a GC cable that had caps.

Any thoughts?

[Yod@]

PAL TVs will be able to strip the sync signal from the composite video signal. So just feed composite video to SCART pin 20. Don't worry about obtaining a pure composite sync signal - usually only things like arcade monitors will need that.

Just ignore the 11v if you don't need it. It's just that some TVs won't switch to RGB unless there's a switching voltage preset on both pins 8 AND 16, and some sets need a relatively high voltage on pin 8 for switching.

If yours works fine with just 5v, then don't worry about using the 11v supply.

I've no idea why the caps don't work on a PAL SNES, but well-known that you just have to remove the caps to get an RGB signal.

[Guest_MKL]

Yes, 11v was quite unnecessary and the RGB signal is just perfect without caps or resistors in between.

The rear of my snes with the new connectors installed:

http://img22.photobucket.com/albums/v65/nassivera/CPS2/6.jpg