I got this Data East – Midnight Resistance pcb from a friend.
He said that he dropped a ground wire onto the pcb by mistake and he thought it touched the pins on one of the L7B0072 custom ICs.
I booted the pcb and the game was running blind. Sounds and inputs was working fine, but a complete black image on the screen.
Been working on this hardware before, I knew that the palette RAM was located at J21 and J22, so I started checking their datalines with the scope
Hmm, zero activity
I then piggybacked a pair of new RAMs (6116 type) on top of the original RAMs
Voila, graphics are back 🙂
I then promptly desoldered the RAMs
and soldered a pair of sockets in their place. And the new RAMs
Job done 🙂