Hello,
I been trying to get a Sega Master System game to work called R-type. Unfortunately I haven't had any success and believe that its the chips itself having problems. I then discovered a video on youtube based on fixing Sega Genesis games that testing pins of the chip using the diode mode on a multimeter, from ground to the pin, and if I had one pin from the chip that doesn't allow any current, to solder a 1k resistor to complete the circuit from the pin and ground. I tested that on a genesis game that had the same problem, and it works!
Video here: https://www.youtube.com/watch?v=eCT4ZKV20RI&t=161s
My question is, is that possible to do the same technique with a Sega master system game? If so, what resistor should I use?