I got the idea for this from Lawrence's custom video connector (http://www.gamesx.com/misctech/mypin.htm) using a DB-9. I thought it was a good idea, but thought that it would be neat if it also powered the system through a custom connector.
The advantage to using this would be that you can plug and unplug any system with just ONE plug. Additionally, by mounting it directly on the deck, and wiring the connections internally, I saved on wiring adaptor costs (by not having to buy and then hack a SCART cord) and it's less cluttered. And finally, you can add more connections that his plug doesn't handle, like Component.
Of course, you don't have to wire this connector internally. If you don't like hacking up your game system, or you don't think you can handle the crammed solder points inside, you can wire the whole DB-25 setup externally. You would cut a SCART wire and a wall transformer wire, and have them both coming out of the single DB-25 connector. But, what about the newer systems that have an internal transformer? I don't really feel good about running high voltage on this plug. So, you wouldn't be able to power the newer systems unless you do wire it internally, bypassing the built-in transformers so you can supply low voltage.
PINOUT (I made it up)
Note: Don't use this pinout! I've since come up with a better idea. I'm going to make the pinout match Lawrence's custom connector (http://www.gamesx.com/misctech/mypin.htm) when you use a standard serial 9 to 25 pin adaptor (http://www.gamesx.com/hwb/ad_9to25Serial.html). (Just without power, component, etc)
Gender: Female on TV/power supply-side (prevents shorting out the power pins accidentally with a random metal object like a house-key)
1.+12
2.+9
3.+5
4.+3.3
5.GND
6.Audio L
7.Audio R
8.Composite
9.S Luminance
10.S Chrominance
11.Component Video #1
12.Component Video #2
13.Component Video #3
14.R
15.G
16.B
17.Horizontal Sync
18.Vertical Sync
19.Composite Sync
20.Digital Audio
21.Digital Video
What I did
I flush-mounted a DB-25 connector on a Genesis 32x, and then soldered the wires from the pins to the connections above (skipping the ones that are unavailable like S-Video grr). To do this, I drilled two holes, and then used a dremmel tool to cut in between. The connector is located right above the power and video connections.
The reason I chose the 32x is because I wanted my CDX to output RGB to my projector. Since the CDX's output goes into the 32x, and then the 32X outputs to the TV, I was able to do my entire plan without modifying the CDX (a good thing since it's so expensive). I plan to make a power jumper from the 32X to the CDX by simply making a cord with a DC power plug on either side like is on the wall transformer cord. However, I have not yet built the power supply section of the TV side, and just have output going to the projector.
I have taken pictures, I will add them soon.
Quality
This is really the only possible problem. What will running the power alongside the video do to the video signal? How will running 8" unshielded wires inside the system for video affect the video signal?
I used a cut-off monitor cord to connect this to my projector. It has individually shielded RGB wires internally. I soldered these directly to a DB-25 plug to test the system, but it didn't work because the Genesis RGB output is too hot. I had to add resistors. So now the plug is a mess with no cover, resistors soldered on and stuff like that. Also, the Genesis is not being powered through the DB-25, yet. I will of course fix all this up later, but I can tell you the results so far.
The quality so far is pretty good. I see a little random noise in solid colors, but the signal is overly attenuated to the point where I have to max out the contrast and brightness, currently. So, I'll have to see what it looks like when I attenuate it properly.
Crosstalk: I haven't really noticed any crosstalk between the RGB components.
So, the quality is definately passable. I haven't yet tested using a standard DB-25 extension cord, so I'll have to see if that makes it total crap. But, even with the problems I described, it definately looks good enough for most people. I'm very picky, but even I could live with the picture the way it is now.
that sounds really interesting, id love to see some pics. if it can really cut down those 32x wires into one i might try using it for my portable cdx. ill be putting some pics up here when im one with that as well. sounds complex though, just *maybe* alittle over my head :-p
-Segasonicfan
Sorry the pictures are taking so long. I'll get them up today. You *could* use one of those jumper cables going from the CDX to the 32x, just cut into that and that would work. But then you don't have the jumper cable. If you have an extra, I suppose you could do that. I decided to just cut into the 32x myself.
Anyway, I should have the pictures up today. I took the pictures when it was apart, and I have them on the camera, and I've looked at them. I just didn't bother to put them up. I'll get it today hopefully.
I know that running a powerline parallel to any signal line is supposed to cause noise. I know when its a 110 volt AC line then the protons "jump", but a 8-12volt dc line probly wont make much noise. Still i wouldnt do it.