Does NeoGeo AES RGB output need to be amped?

iatneH · Post by **iatneH** » Fri Mar 21, 2008 6:27 am

I have a Japanese AES system with super high serial in the 160K range.

I made a cable for passing through to an external RGB->NTSC encoder, the video works for about a second when I boot up, but quickly darkens and then blacks out completely.

I have tried this cable on both JROK 3.1 and JROK 4.1 through the S-video output with the same result.

What's going on here? I would like to avoid cracking open my system, so is there anything I can do as an external cable mod?

Or did I just not wire something up properly?

neorichieb1971 · Post by **neorichieb1971** » Fri Mar 21, 2008 12:02 pm

There is a mod you can do where the AES RGB video chip is exchanged for an MVS one, which is much better. None of the AES models compare.

MKL · Post by **MKL** » Fri Mar 21, 2008 6:19 pm

Given the 160k serial your neo is probably either revision 3-5 or 3-6. The A/V port on these revisions doesn't have sync out and the RGB converter needs this.

http://gamesx.com/wiki/doku.php?id=av:neogeoav

To get around this you can either build a small circuit with a LM1881 and strip sync from composite video or mod the system and add sync out to the A/V port. The latter method is easier and better.

And while you're at it, if you have revision 3-6, you may want to fix the bad RGB typical of this revision (shows up as the infamous vertical striping) by cutting three traces on the motherboard. Details here

iatneH · Post by **iatneH** » Fri Mar 21, 2008 8:15 pm

Awesome, thanks for the information MKL! I had no idea about C.video being duplicated onto the Sync pin on some motherboards.

While most of the time I would hack up my systems without blinking an eye, I think for this I will go with the LM1881.

iatneH · Post by **iatneH** » Sat Apr 19, 2008 6:01 am

Once again thanks MKL, I finally got around to fixing my cable tonight with a LM1881N, and the lack of separate sync on the late AES motherboard was indeed the problem.

Just barely managed to fit the IC, 2 capacitors, and resistor inside my existing DB-9 connector housing, same way I saw it at gamesx. It's a real tight squeeze! Here's the IC and one capacitor; the resistor and second capacitor are on the other side.