I was lucky enough to pick up a cheap PAL GameCube RGB Lead recently. The RGB picture is fantastic on my CRT telly, and not too bad on my LCD (although I’ve got an upscaler for it now), but it doesn’t automatically switch the TV to the correct channel like you would expect.
If you check out the diagrams on Tims page and the info at GamesX then you’ll see that Pin 3 of Nintendo’s Multi AV socket differs depending on the consoles region. So a PAL Gamecube outputs +12v on Pin 3, which in turn is wired up to Scart Pin 8 to switch the telly to the correct channel.
The NTSC SNES/Super Famicom and N64 output Composite Sync on Pin 3, which isn’t what your TV is expecting in Scart Pin 8. It’s unlikely to cause any damage, but it’s easily altered.
Opening up the Cube RGB Cable is not fun. You have to squeeze in 4 clips and then unscrew the unscrewy bit. I use a plastic bit pointy thing, but a screwdriver would be fine, to push each of the clips past the bit that stops you being able to unscrew the casing. If you’re careful you can push all 4 down, and then do one turn. Repeat about 3 or 4 times and you should then be able to unscrew it completely.
You’ll now see the circuit board built into the cable. This bit is easy, look for this red wire and cut it (I cut it in the middle so it would be easy to reverse this should I ever need to), insulate the cut wire with a bit of tape to be extra safe. Then with your soldering iron, link up the two points shown.
This will take the +5v which is wired up to go to Scart Pin 16 (via a resistor) so that it now also goes to Scart Pin 8.
Maybe you want to cut off those clips that stop you unscrewing the scart casing easily, just in case you want to open it up again another time? I did.
There is a lot of info regarding Official Nintendo Cables on GamesX forum courtesy of Link83 (he keeps popping up on this site!!)
Turns out that Link83 has got a lot of brilliant info on this, please take the time to read this extra info, which might help you if you’re still having problems with this cable. As it stands, this will switch your Widescreen TV to 16:9 mode, this is because the voltage supplied on Scart Pin 8 is not high enough. Anyway, here’s Link83s info:
The only thing I would suggest is maybe adding this link to Wikipedia to explain how Scart switching works:-http://en.wikipedia.org/wiki/Scart#Blanking_and_switching and also you might want to mention that once this mod is done the cable will only ever switch to the AV1/RGB channel in ‘Widescreen’ mode instead of ‘4:3’. Also, it might be good to have a picture of how best to remove those nasty clips? The first time I removed them I cut a bit too much off the casing and removed the bits that hold the cables rubber gromet in place so it would slide up and down the cable and i had to glue it in place. Now I usually use some ‘precision cutters’ to snip off the very end ‘ridged’ bit, and then scrape away any remaining bit of the ‘catches’ if that makes sense. I can take a picture of how I remove the clips if it helps?
Also, although the above modification is useful for the NTSC SNES and NTSC N64 consoles, there is an alternative solution for the NTSC N64 since it does have a +12V line on the motherboard (Unlike the NTSC SNES which runs entirely on +5V) Viletim over at the nfgforums told me I could enable ‘proper’ 4:3 Scart switching for the N64 by connecting the N64’s +12V line to the AV port if I used a 220R 0.5W or 1W resistor between the +12V line and AV port Pin 3 (Viletim says a 1W resistor would be best but that 0.5W should be fine, the resistor is there for protection in case of a short circuit) You obviously need to cut the trace going to the AV port Pin 3 first to disable C-Sync (You have to make absolutely sure the trace is cut or you will fry the N64) and you want to use the +12V line coming away from the power switch, since otherwise it would be sending +12V though the N64 all the time. The best spot I found to use is a small circled via on the back of the N64 motherboard between points Q1 and C129.
Also, I dont know if this is worth mentioning or if it will cause more confusion, but the official PAL GameCube Scart cable has a 75ohm resistor to ground and 220uF capacitor in series on the Composite video line – these are needed for PAL consoles but not NTSC consoles. Usually these two components dont cause any problems when using on an NTSC SNES/N64 console, but on one of my TV’s they did cause the picture to ‘jump’ every so often, because RGB Scart gets the Sync signal from Composite video. You can remove/bypass these two components but the 75ohm resistor is a pain to remove as its hidden in the other end of the Scart cable!
UPDATE by FourX
I’ve just finished doing the newer N64 RGB amp mod the one with the THS7314 Chip, (Nice little chip), anyway for some reason my LCD TV doesn’t like some Composite Video signals when it comes to consoles some are ok but some have sync problems like the mega drive.
when I finished the new N64 RGB Amp the picture was ok but sometimes it would go out of sync and wobble “NOT GOOD” so i did some digging around and found the N64 can output C-Sync (like in the MD Sync Issues on LCD TV Guide), so I tried it with C-Sync instead of Composite Video and now the picture is awesome, it looks a little sharper “more defined” to me when using C-Sync and NO more sync wobble (Wahoo).
oh yes, like in the picture please don’t try this on a PAL N64 unless you want your TV to go Bye Bye, 12v to the Sync input on your TV in not a good thing I would think, USA and Japanese N64’s have the same pin-outs so this guide will work on all NTSC N64’s
More info now, thank you to Retro Accessories for sharing how to restore C-Sync back into NTSC N64’s that are missing it.
Following on from Link83’s info above, I decided to reverse the cable mod, and instead modify my consoles as I wasn’t using C-Sync at all. For my Super Famicom I simply cut the trace leading to pin 3 of the AV socket (cut circled in red in the photo), and linked it up to pin 10 (5v, which will switch a widescreen TV into widescreen mode, I guess I could have got 10v from the input of the 7805 voltage regulator and used that, maybe after putting a second voltage regulator to reduce it to a steady 9v, but I wasn’t worried about widescreen mode at this point).
When cutting a trace like this, I use a sharp craft knife/scalpel blade and put two little cuts close together, then use the blade to pick the bit of trace inbetween the cuts out. I try to choose an area which is clear of other traces and/or cut in a direction away from other traces.
My Nintendo 64 is one which doesn’t have the components for Composite Sync anyway, so wiring it for 12v was very easy. I chose a 12v source and linked it to a solder pad that was linked to pin 3. The 12v source I chose is mentioned by Link83 elsewhere on this page. My link wire is the purple one in the photo (the rest of the stuff is my RGB mod/amp).