This may be a lost cause, but I'd like to get to the bottom of this issue.
I have picked up a Gradius board (Bubble System version) that is showing no signs of life whatsoever. My power lines are fine, although the 12V and -12V rails look to be a little on the low side measuring 11.11V and -11.2V respectively. Those don't seem to be the issue and I can confirm the video board works as I can use it on my Salamander board just fine (after cutting out notches in the ribbon cables and reversing the board, of course). What I did find, though, has me perplexed.
The board is stuck in a reset state. All the reset lines on the board are stuck low and I'm having a really hard time retracing the reset circuit (gotta love not having the necessary technical documents on hand - the only schematic I have is from Nemesis, which uses a totally different ROM board, but shares the same video board). I don't know if anyone has any idea how the reset circuit works on a Bubble System board, but for now, I'm stuck. I've replaced three transistors and one capacitor, none of which fixed the problem. If this is a sign the bubble memory is shot, then I guess nothing can be done about it, but I need confirmation first.
Does anybody know if schematics exist for the Konami Bubble System? Those would be of great help to me.