Why do we need batteries in our pinball and arcade machines? It sounds absurd now because we have the technology now to store updatable information electronically without power. But not so long ago the only way to store data was on magnetic media like a floppy disk or mechanical hard drive.
Back when your machine was made no such technology was available so to solve this problem they had to supply constant power to a single ram ic that stored high scores and other configuration data. Through the ages they got better at this using watch batteries that were safe to do this job. But early on we had nicad and regular AA batteries doing this job. Both will leak overtime. All of these engineers compounded the problem by putting this time bomb on the main board. It does not matter what pinball machine or arcade game you have there it sits ready to destroy your board. If your machine uses a watch battery or one of the timekeeper ICs or the combo cmos ram / battery ICs you are lucky and can relax. But for the rest of us we need to open up our machines and locate the battery remove it immediately and modify the board to put a battery holder off to the side where if it leaks no damage can be done to the board.
Damage to your board and nearby boards can be severe and silent. The acid will creep up under the solder mask (green covering on boards) as it eats away the copper it travels along these paths destroying components and copper traces all the way. It is amazing to see how much damage can be done to a board before it starts to malfunction. Once your machine starts to act up it is almost too late acid has usually eaten its way through a chunk of your board and the only way to stop it is to scrape off the solder mask and scrape away all the corroded copper and solder. That process because the copper traces are barely hanging on will damage the board further and require allot of rework. I used to try and repair these boards. But I have found that they will take extraordinary work to repair and still the boards can be unstable. If available I will now replace the boards with new ones. Sometimes there may be no hope and you can lose your machine. At this point you are searching ebay for a new board.
The moral of the story is to check your machines and if you have one on your board GET IT OFF RIGHT AWAY.
If you feel uncomfortable doing this yourself, if you bring your board to us we can change this out for you. It a simple cost effective alteration we can do on any board.