SNK NeoGeo 4 slot arcade pcb repair #2
Another 4 slot – a previous owner had installed a new battery and replaced the palette RAM. The board now reported a RAM error with the original BIOS, and the diagnostic ROM confirmed it as the upper WRAM chip (see my previous 4 slot repair).
If you don’t have a SMT desolder station then (if you dare) you can remove surface mount chips with a heat-gun and some tinfoil to protect the surrounding areas. The chips are capable of taking quite a lot of heat so the only worry is warping the board rather than damaging a chip. Because there’s very little solder holding the SMT chips on though, they come off quite easily.
With that one RAM chip replaced, everything worked!