CPS-2 Suicide Batteries

Mar 5, 2012 capcom cps2

Today, I changed the suicide batteries on my Capcom CPS-2 boards.

Each CPS-2 “B” board contains a battery that is used to keep a volatile memory powered that stores decryption keys required to run the game. Since Capcom CPS-1 games were heavily bootlegged (which is why there were all kinds of wacky Street Fighter II variants), Capcom took some pretty drastic measures to prevent bootlegs of CPS-2 games.

Basically, if the battery dies, the decryption keys are lost and the game can no longer be played, hence the term “suicide battery” since the game basically kills itself. I have two CPS-2 “B” boards: Mars Matrix and Giga Wing. I got them both from Japan and have no idea when the battery was changed, so I figured I should change them as soon as I could.

I bought some replacement batteries, opened up my boards and took a deep breath. It was a little stressful because if you do something wrong, you can ruin your games. Once the existing battery is desoldered, the clock is ticking and you need to get the new battery wired up ASAP. Capacitors on the board will hold a charge for a few minutes while you change the battery, but if they run out of juice, those decryption keys will be lost and the game will be ruined.

Thankfully, the task itself is really easy. I heated up both my soldering iron and my desoldering iron. Use the desoldering iron to desolder and remove the old battery. Stick the new battery’s wires through the holes on the PCB, then solder it into place. Screw everything back together, then power up the game and take a deep breath. Thankfully, both of my games still work. Guidance says to change the batteries every 5 years, so I won’t have to worry about it again until 2017.

If I had screwed something up, thankfully the encryption for the CPS-2 was broken in 2001. This has led to interesting developments, including being able to play CPS-2 games in MAME, as well as resurrect dead boards. These boards are said to have been “phoenixed” since they have been revived from death, however some view phoenixes games as bootlegs since the EEPROMs have been swapped for non-official versions. I’m glad that I was able to not ruin my boards, but if I had I would’ve gladly used the phoenix edition EEPROMs to revive them. At the end of the day, I just want to be able to play the games…