Namco Assault arcade pcb repair
(aka Atari Assault, as it was licensed to Atari for the USA).
Board would boot up and sometimes say DRAM error, but most often would not boot properly at all and just constantly reset. I used the MAME debugger to confirm any error with the main CPU RAM causes the DRAM error message. The nice thing about this pcb is all the RAM is in sockets from the factory – so very quick to swap out main RAM for spares.
This indeed fixed the DRAM error and sometimes the game would play perfectly – but still sometimes it would not boot at all. As so many things are in sockets on this board I removed everything I could and cleaned the pcb and all sockets – Simple Green and paintbrush then rinse with water. PCB looked as good as new! Even better it booted 100% of the time with everything replaced.