Recently I was able to get a bunch of arcade motherboards from the mid 90's. Some of them functioned perfectly, but others did not. Being almost 20 years old, these game are disappearing at an alarming rate, so it's up to enthusiasts to preserve them for the future.
Today, I will show you how to replace the "Suicide Battery" in a Capcom CPS2 board.
The CPS2 was a platform that Capcom used to develop several hit arcade games from the past, including a number of Street Fighter sequels, Alien Vs. Predator, Dungeons and Dragons, and some of the first entries in the Vs. fighter series. These boards were very advanced for their time, featuring switchable "A" board cartridges that easily changed games for arcade operators. They also featured a form of copy protection that stored encryption keys inside volatile memory on the board.
This memory is kept alive with a small lithium battery on the board. As long as this battery is capable of keeping the memory charged, the keys work and the game is playable. When the batteries die though, the memory is erased, making the board lose the keys. That's when the board becomes unplayable. Usually they display a blank, light blue, or green screen, with no audio.
It's quite an issue for pieces of hardware that are becoming increasingly rarer as time goes on.
This is what you need to do in order to prevent this problem. It essentially involves a regular swapping of this battery with a fresh one, every 5-6 years.