Reply To: Megadrive VA0 RGB bypass

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Ok so here’s the story :

I mounted the bypass amp on a VA0 japanese motherboard, so it was a little tricky at the start as it’s a little bit different than the VA4 I used to deal with. I wanted to try on this one because the picture was not good (big big jailbars).

I first lifted the RGB and CSYNC pins on the 315-5313, in order to isolate completely the signals, and also cut traces on the solder side (the back) which lead to the CXA1145, to be sure. From here I mounted the amp just as discribed on the VDP guide.

Image is shaking a lot, like CSYNC is not working.

So I lifted back down the CSYNC pin with the wire still connected on the amp.

I got an image here, but worse than before, with all kind of interferences, massive jailbars, and red seems to be over charged (like sonic’s skin spent too much time under the sun).

After trying hasardous manipulations, the CSYNC pin of the 315-5313 broke. I thought all was lost but I managed to get the image described below back, just by maintaining the amp CSYNC wire in place of the CSYNC pin and hold it with tape. Pretty nasty work.

So, image is still here, but I don’t think I’m going to put my hands inside before knowing exactly how to improve it. If by chance I succed in the improvement, I will have to put glue on that CSYNC wire/pin to avoid it to move.

Voilà voilà…

So the actual problems :
-massive jailbars
-excessive red (colours are not well balanced)