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I have been following the instructions at http://arcadecollecting.com/dead/cps-q.html

Trying to bring a SNSM board back to life. Roms on B board are marked MBU xxB.

I did the C board mod and verified it works (have a punisher also that I phoenixed following the instructions).

I replaced the 23 rom on the b board with the file mbu-23x.rom

I replaced the rom on the Q-Sound board with a 27c040 burned with the slamx.rom

I built the 4002 circuit and ran the wires to the a & q sound boards.

I verified the kabuki is working in the punisher boardset.

I verified the two roms match the images from the instructions.

I verified the pin 31 of the q-sound rom is going to the pin 1 of the 4002. And that the traces are cut between 32,31,30. And that 30 is going to kabuki 27.


But when I boot I get black screen. If the test switch is on when I boot I get the test menu with a bunch of character data overlaid and a message at the bottom "Address error 0000FFF5". Which is what I would expect if I had a bad rom set.

On the scope I can see pin 1 of the 4002 toggles one time before the game locks up. All the inputs to the 4002 are running (though the q-sound 9p:19 enable line only toggles one time).

Any thoughts?