If you're still using the original battery holder on your Williams CPu board you may be asking for trouble. Most of the Williams boards have some kind of acid damage by now due to leaky batteries left in them as they were stored away in the 80's. If you're still using the original AA battery holder make sure to replace the batteries at least once a year and use good quality Alkaline batteries. If you want to avoid the problem all together or need to fix your non working battery section on your Williams CPu board follow along below.
1) Remove the old AA battery holder: Make sure to use a hot soldering iron set around 600-700 degrees with large tip. Those acid damaged areas can be hard to loosen.
2)Clean off the affected area: Use a mixture of baking soda and water (1:1 ratio) and a toothbrush. After cleaning rinse with cold clean water also clean your toothbrush. Then use white vinegar and toothbrush to reclean any area that the acid from the leaky batteries have run on to. Rinse with distilled water and blow dry your board, compressed air works good.
3)Install your new lithium CR2032 battery kit: Important, reduce the heat to around 500 degrees on your soldering iron. If you don't reduce the heat on your soldering iron you may damage the plastic housing on the CR2032 battery holder. Start by soldering in the black jumper cable, this will allow time for the soldering iron to cool.
Solder the CR2032 battery holder in place. Use the top 2 holes closets to Diode 10 (see picture). Make sure the + side of the holder is closets to Diode 10. Now install the jumper at the bottom sets of holes, if you haven't already done so. One side goes closets to Diode 10 and the other side closets to the bottom far right side of the board, this is the black cable in the picture.
You can find these kits at many of the Arcade Shops on line, Ebay and here. The complete kit should be around $5. You may have read the pros and cons of the kit. Some argue that there isn't enough battery power in the CR2032. I have done plenty of these upgrade and I can tell you that the CR2032 has plenty of power to drive a single 5514 CMOS chip for about 2 years and maybe longer. It will not only save you money, since the CR2032 batteries are cheaper than 3 good quality AA batteries but it may also save your board from any more acid damage.
Need to troubleshoot your installation: If your having problems with your installation check out these tips. To troubleshoot disconnect the power or remove the board from the game but keep the battery hooked up. Refer to the picture below.
1) Make sure your battery is installed correctly with the + side up.
2) Is the battery making good connection in the case?
3) Is Diode 10 (D10 = 1N4001) damaged or missing?
4) Hook up a voltage meter to ground (point D in picture below). Measure at point A then B then C to see where you're loosing your voltage.
A: Voltage missing or low at point A would point to a dead battery or problem with your installation of the kit.
B: Voltage missing at point B would point to a bad D10 (1N4001) diode. This diode may have been damaged due to the acid damage.
C: Voltage missing at point C would point to a bad trace from point B to C.