Capcom Black Tiger arcade pcb repair
At first glance this fault appears to be a variant on the common ‘failed sprite linebuffer’ problem that often crops up in arcade pcbs where every 2nd line is missing. In this case though every second line is drawing incorrect sprites – and all up against the left side of the screen. Because there is actual sprite data on every scanline, the line buffer circuits themselves must be working – it’s what is being put into one of them that is the fault.
As the sprite tile is wrong the address lines of the sprite ROMs are the first place to start (as the address lines control what tile is output to the line buffers). The address lines all trace back to the 86S105 custom chip and unfortunately it’s where this repair ends. This chip completely integrates the frontend of the sprite processing and seems to have failed internally. The chip itself is almost certainly based on the design of earlier Capcom sprite generators like Ghosts n Goblins. That game has RAM for the sprite list, then two more RAM chips for an attribute buffer that alternate every scanline. Most likely one RAM or supporting logic has failed.
Interestingly some Googling revealed a picture of a Black Tiger prototype where the custom chip was replaced with regular TTL – and although the picture is low res the 3 6116 RAM chips can clearly be seen.
The only fix is to replace this custom chip, which is also used on 1943 and Buster Bros/Pang.
Update, some weeks later..
Well, thanks to JoeyBagODonuts on KLOV who donated a broken Super Pang this board is working perfectly again. The 86S105 custom was swapped and everything worked!