Step 16: Disabling the Lockout Chip
This is an optional step, you may skip it if you like.
What you need:
Piece of wire
The lockout chip in the NES was included to prevent pirated games from running in the console. It is also the reason that you get the blinking screen. If the console's lockout chip and the cartridge's lockout chip don't communicate, then the game won't play. Half the time, it's not because of dirty contacts. The games would run fine if it weren't for the lockout chips. Disabling it means a much higher success rate.
PULLING UP PIN 4
To disable the lockout chip on the NES, first locate the actual chip. It is close to where we soldered the video amp, and it is labeled 3193A.
You need to pull up pin 4 of the lockout chip. Taking the whole chip out won't work, because it is connected to the reset line, and the console won't run without it. Instead, find pin 4 of the chip. The first picture shows pin 4. Put the small screwdriver under the pin to kind of pull it out of the hole. At the same time, heat the lead from the other side of the board with your soldering iron. Pull the pin out so it's not connected to the board.
GROUNDING THE PIN
You could be done right there. The lockout chip is disabled right now, but it is still a good idea to connect the pin to ground. Take your piece of wire and solder one end to the pin you pulled up, and the other end to the silver grounding strip going all around the board.
All your games should now run very well. The NES board is now complete. Next we'll build the power supply for it and test it out!