iz8dwf | Gallag arcade (Galaga) #3. Final repair (with lots of Z80 code!) @iz8dwf | Uploaded December 2019 | Updated October 2024, 2 hours ago.
Gallag PCB (Galaga bootleg) repaired finally!
It was a stupid 2114 SRAM all the time, but I took the longest way to find it: reverse engineering the schematic and part of the firmware and then writing my own diagnostic code to confirm I had a bad RAM chip.
I also got a replacement sound PROM chip that I had damaged during
the troubleshooting process. See part #2 here:
youtube.com/watch?v=xXWhWXN6LkQ

Gallag color output correction:
jrok.com/project/gallag/gallag_color_correction.htm


Diagnostic code I wrote and used in the video:
drive.google.com/open?id=1uyMHEp8i_zpsiN8xDnJZia7g4QZ7j-cW