NES to JAMMA

[Masamune69500]

I am struggling on this one.
For every other console, it's easy to get hold on the RGB but for the NES/Famicom, I could get only the S-video.

I know the titler have the RGB inside but I never found on the web a good explanation how to take the RGB and the sync out of it.

Is it possible to connect the S-video to Jamma? I don't want to go through VGA because it imply too many conversions.

It's to play with Recca and Crisis Force

[Ex-Cyber]

You pretty much only have two options:

1) Get an RGB PPU (from e.g. a PlayChoice-10, Vs. board, Famicom Titler; this would give you the most colorful / sharpest output but probably an inaccurate palette)

2) Buy/build an S-Video/NTSC decoder (probably the best way to get "authentic" graphics but also introduces other artifacts)

The issue with NES/Famicom is that the original PPU does direct digital synthesis of the NTSC chroma signal. As a result there isn't any well-defined "NES palette" in the per-pixel RGB sense. NTSC color artifacts are inherently part of the system.

[Masamune69500]

Thanks

1) I can get a famicom titler with the PPU but I don't know how to extract the RGB/Sync/Video ground from it to connect it to a JAMMA.
2) A S-video -> NTSC converter could be interesting but I need one which output Scart RGB signal. Do you have any recommandation/link?

[Ex-Cyber]

For getting RGB out of a Famicom Titler: http://www.disgruntleddesigner.com/chri ... itler.html

As for a decoder (note that I mean NTSC or S-Video to RGB; going between NTSC and S-Video is much simpler and doesn't really involve encoding/decoding), I don't really know what to suggest. It's something that's been a standard feature of television sets for decades and there are many different circuits to do it (with varying levels of complexity, performance, cost, component availability, etc.).

[Masamune69500]

I know this webpage but it just says to get the RGB there and put some resistors.
It doesn't say which resistor, where to take the video ground and the sync

[Ex-Cyber]

I failed to notice that issue. Since he doesn't talk about grabbing a sync signal directly, he might be running the composite or luma signal through a sync separator such as the LM1881. Or if it's using a documented NTSC encoder, he might have just tapped it at that end. As for video ground, maybe look at what the shield/ring connection of the onboard NTSC output is connected to, but it's probably just going to end up being a supply ground since these signals seem to go all over the place.

[dorakyura]

I did the mod the way ex-cyber described, i.e. canabalized a PlayChoice-10 board and re-soldered it into my Famicom new style. Problem 1: It’s been a while since then and I don’t remember what resistors I used. Problem 2: I don’t have it with me right so I could open it and have a look …

But: If it’s any help I’ll do exactly that on the weekend (maybe even tomorrow).

[antron]

I got one of these to do the job:

http://cgi.ebay.com/NEW-Extron-60-145-0 ... 3ca6c2893e

[Masamune69500]

Thanks dorakyura, if you have time and don't mind, I will appreciate but don't waste your time with it.
I checked what antron was using, it output RGBHV RCA style. Did you rip off 4 cable to connect them to the Jamma board.
How does the image look like with this converter.

[antron]

Thanks dorakyura, if you have time and don't mind, I will appreciate but don't waste your time with it.
I checked what antron was using, it output RGBHV RCA style. Did you rip off 4 cable to connect them to the Jamma board.
How does the image look like with this converter.

they are BNC, and I got a BNC->DB15(VGA) and it looked fine on my tri-sync. by fine i mean it looked like composite video.

you can get some BNC connectors and make a cable to go to a jamma fingerboard.
you will also need a RCA to BNC adapter to get the signal in (or s-video to BNC x2 cable for consoles with s-video)

[dorakyura]

Hi Masamune69500,

sorry, my brother took my tools with him , so I haven't been able too open the Famicom up just yet. In the meantime I tried to capture the picture quality for you, see here:

http://picasaweb.google.com/ibarakuro

It really doesn't show too good, but quality is pristine, more than worth it.

[dorakyura]

Hey Masamune69500,

finally I was able to add some interesting pics to the picasa album. I did not come up with the postprocessing circuit myself – hopefully I got everything right.

Bye
dorakyura