There is a small pcb vertically mounted just in front of the pin amp ic , you will find a trimmer for trapezoid on this pcb.
Just remove this and check for broken solder joints on any pins .
Mistercade is an awesome project wich I love but there are issues on jamma rgb out! Not only on MS8 and 2930 ! And not only the V2, I have two V1 and not perform at same level of a genuine jamma ! The signal is not cristal clear eaven on MS9! The analog port is just perfect ! The jamma...
If you got no red, most likely there is something damage on the neck board, not the tube! just swap the neck board to confirm this, then will be easy to address the issue just comparing the two neck board PCB , just testing any component in red line