CPS A Board Jail Bars

I have an issue where my CPS1 A Board is showing some vertical jail bars. This happens on ANY CPS1 B Board that I connect to it. Anyone have any idea which A Board components I should probe or replace?

Thanks!

 

These aren't really "jailbars" (character data bus), it's quite a bit more complicated. The repeating pattern suggests an open low-order address line (presumably A4/A5) to a/a group of character ROM, but since it affects multiple layers the fault could also be in the VRAM subsystem (either address or data buses) or in the address multiplex logic. Without someone to offer intimate knowledge of CPS hardware, which in my experience nobody online has, you'll probably have to follow a general repair workflow like inspecting traces and solder joints. You can start by tracing the character ROM address lines back form the B board over the IDC connector.

 

Yep. Most people I have spoke with just replace the A board altogether because of it's complexity. I will start inspecting traces and solder joints. Thanks for the tip!