Previously, I've posted about how to make a 32KB re-writable Sega Master System cartridge using an EPROM an an original SMS game.
In this hack, the !WR line from the Sega cart slot was connected to the EPROM programming voltage pin.
Although I have never, ever had problems with my systems and this hack, someone has suggested that the EPROM could possibly draw too much current from the !WR line via the programming voltage pin.
One easy way to fix this is to 1) cut the trace going to the programming voltage pin of the EPROM and 2) solder a wire from VCC to the programming voltage pin. I have tested this and the cart still work fine. See below for a picture of the simple modification.