Installed the bypass on my va0 today. Followed the guide, respecting board differences. The worst one is the absence of RF modilator on japanese boards. Put my amp above the ym2610 chip (yeah, I know the “right place” is above vdp). Pulled 5v and ground from daughterboard.Heavy jailbars and interference(oscillator is nearby), but picture is ok, notable color vibrancy from the new amp. Then, changed to regulator’s 5v and gnd. Almost solved. The jailbars are still there, but at an acceptable level, after I put thicker and shorter wires.
Lessons learned: isolate the board the best you can, this thing catches too much interference.
I finished my installation after viewing this