Help with RCA video out!

[villahed94]

I've just modded my VA2 Model 1 Genesis to have a CXA2075 encoder. Video looks great, but composite looks much worse with the MD's internal circuit than with Sony's application circuit schematic. Megadrive's internal circuit induces too much distortion and a lot of rainbow banding to the image
My question is: Is there any way I can bypass this circuit , and feed video back to both the RF modulator and the DIN connector?

Any help is appreciated.

[Guntz]

Well, for the DIN connector, composite can be tapped at this solder joint, it has a cable attached to it. The joint cluster you see is the underside of the DIN connector.



As for the RF modulator, there's 3 pins facing opposite of the RCA jack that solder into the PCB. I don't immediately know the pinout but one is definitely composite. The others may be sound and/or ground.

Actually, this is probably a good place to post my own problem. I've tried tapping composite from the DIN connector and soldering it to an RCA jack, but the picture has noise in it. I've tried using thick wire but there's no difference. The picture is much worse in PAL mode. Composite from the DIN jack is just fine. What am I doing wrong?

[villahed94]

Use shorter cables. Thin cables are prone to a lot of interference. There might be some grounding problem too.

[Lastcallhall]

You may want to try a small (1000pF or so) cap to clean the line. Just a thought.

[tz101]

Wrap internal wires with aluminum foil and, presto, no more interference.

[Guntz]

Hmm, I suppose it'd be worth trying. However I'd have to buy some. Do most mods in general use the same 0.1uf ceramic caps or does the rating vary? Can I buy like a pack of 100 or something and be set?

Wrap internal wires with aluminum foil and, presto, no more interference.

That doesn't sound very safe considering that tin foil could very easily short something. I keep the RF shielding in my Genesis though.

It's awfully strange this Genesis is giving me such problems with the composite video though, I've used the same wire in my TG16 and the video is perfect in that system. It also lacks half it's RF shielding.

[villahed94]

Any help about the RF modulator pinout?

[tz101]

That doesn't sound very safe considering that tin foil could very easily short something. I keep the RF shielding in my Genesis though.

The RF shield that came with your Genesis will not keep any additional wires you solder inside the console from interference. Wrapping them in metal foil works great for this purpose, and can be insulated by wrapping the foil in electrical tape if you are considered about shorting out issues. Or, you could just put a plastic/rubber sheet between the foil-covered wires and the PCB of the console.