Aliexpress Famicom motherboard video issues

[nullray]

I have a non functioning original Famicom that has severe water damage. Browsing Aliexpress I saw there is a seller offering aftermarket motherboards. You just supply the CPU/PPU and some ports.

I decided to try it on a lark. The build quality is not at all bad, and the system sort of works. The problem I have is with the video.

It shipped with a PAL crystal that I swapped out for an NTSC compatible crystal(the original one from the Famicom). When I have the console connected to a CRT the picture mostly rolls OR is really shaky/jittery. Aside from that the console does appear to function. You can play games and controls all seem to be fine.

I attempted to trace out the video pathway and it _looks_ like it is following the composite schematic as found in the NESdev wiki.

I have a couple imgur galleries here:

Board shots
Video pathway

I was curious if anyone here has any experience with these boards. I was also wondering if anyone would know why the picture is so wonky.

Thanks in advance for any help/info!

[Pikkon]

What I would do is completely bypass the video circuit and grab video directly from pin 21 of the ppu,the video will look bad but will rule out if your picture is stable.

Also does your crt support ntsc and have you tried it on different tv's.

[nullray]

Yeah it is an NTSC TV. I've not tried it on anything other the one TV and the Retrotink. Looks good on the RT but jacked on the real TV. I suspect the RT4K is just more tolerant of the thready signal.

The RT does report that it is an NTSC signal which is sort of good news.

I'll check the video off of the pin and see what it looks like.