Williams WPC CPU Board Battery Corrosion Repairs (Including a Scratch Build)

It seems to be the season for battery corrosion on pinball circuit boards. Over the last few months I have repaired several Williams WPC-era MPU (CPU) boards which have suffered various levels of battery corrosion. Original WPC CPU boards are now at least 33 years old, which is an eternity when it comes to electronics. By this point, a randomly-selected CPU board will have had many issues during its working life which would have necessitated bench-level repair. However, for the most part, these repairs would have consisted of replacement of a couple of defective components; a relatively non-invasive procedure. Battery corrosion repair is a different beast, and is more akin to amputation followed by transplantation. 

Unfortunately for the boards featured in this blog post, the corrosion was discovered too late, so some extensive repairs had to be carried out. This post deals with three levels of battery corrosion: minor, moderate, and major, and the actions undertaken to get the games back into working condition. There is some great information available regarding how to tackle these kinds of repairs, such as the Alkaline Corrosion Abatement section on Pinwiki, and TerryB's Guide to Repairing Alkaline Battery Damage. I used tips from both guides to carry out these repairs. 

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