Namco Galaga arcade pcb repair
A pair of Galaga boards, both of which displayed garbage and continually reset. First thing to check is the usual basics – do the CPUs have a clock signal, is the reset line working correctly, is the data on the ROMs valid? Between both boards 3 failed CPUs and 4 bad eproms were found. With them replaced problems such as random resets and missing sounds remained – but after a lot of debugging it all came down to dirty sockets or corroded chip legs. After a clean-up both boards were stable.
One fault remained on one of the boards – for all sprites only the blue channel was displayed – unfortunately this turned out to be a failure of the sprite color PROM at location 1C on the video board. A replacement was pulled from a bootleg Gallag in order to fix the original board.