May 082018
 

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 🙂