Williams CPU Board: Battery Conversion to CR2032
A common failure with untested, damaged or broken Williams CPUs is battery acid damage from the 3x AA cells which keep the settings and bookkeeping information in the CMOS RAM when the game is switched off. This simple modification removes the need for the 3x AA batteries, replacing them with a single CR2032 lithium coin cell that is much less likely to leak.
This modification applies equally to the early video games (such as Defender, Stargate, Robotron, Joust, Sinistar, Bubbles and Splat!) and early solid state Pinballs where the battery is not charged (as is the case on Bally 6800 boards).
Don't worry that CR2032 is only 3v as the CMOS RAM specification states that it will work down to 2v.
The modification is the same for all the Williams video games except early Defender boards which will be covered separately.
Carrying out the Modification - Front:
Remove the existing 3x AA cell battery holder.
Place the positive terminal of the CR2032 lithium battery holder in the upper (+ terminal) left hand hole and the negative terminal of the battery holder in the upper (+ terminal) middle hole as shown.
Solder in the battery holder.
Carrying out the Modification - Rear:
Add a Jumper wire between the two outside lower holes as shown.
Add a CR2032 battery.
Early Defender Boards
Early series Defender CPU boards have a slightly different layout so although the process is the same the connections are slightly different.
Early Defender CPU Carrying out the Modification - Front:
Remove the existing 3x AA cell battery holder.
Place the positive terminal of the CR2032 lithium battery holder in the middle (- terminal) left hand hole and the negative terminal of the battery holder in the upper (- terminal) left hand hole as shown.
Solder in the battery holder.
Early Defender CPU Carrying out the Modification - Rear:
Add a Jumper wire between the top and bottom left hand holes as shown.
Add a CR2032 battery.
