INSTALLING A SUPER CAPACITOR INTO WILLIAMS SYSTEM 6 CPU

[ddstoys]

For those who are unfamiliar with super capacitors they are a small capacitor which can hold its charge for a long time and are a perfect replacement for batteries with no damage causing acid inside them.   Ive installed these into a few Bally machines but thought id have a crack at a Williams System 6 cpu.

  These are available from Jaycar for around $5 each and are  1farrad 5.5v item and are cheaper than batteries and will last for a lot longer 

First thing is to remove the old batteries.   Then i checked the back of the cpu near the + battery terminal to make sure im not drilling any tracks on the back of the board and drilled a hole through the pcb in the right place for the second leg of the super capacitor.

[ddstoys]

Before installing the super cap check the volatages between the + and negative battery terminal with the game switched on if you get 5v you can skip the last step

Then i installed the Super Cap making sure ive inserted the + leg into the terminal and the -ve into the drilled hole.

[ddstoys]

Flip the CPU over then solder the positive leg into the original hole then run a jumper wire across to the Negative terminal of the battery pack and solder to the other leg of the Cap as shown.

[ddstoys]

Now im no expert with this stuff so if im wrong step in fellas but its working in firepower.    

Before installing your super cap turn the game on without batteries and with a multi meter measure the voltage between the + and - battery terminals.   If you have 5v then you can leave the board as it is if you are getting no voltage then you will need to run a jumper across where the diode is to allow the voltage back to charge the capacitor as these board use standard non rechargable batteries so the diode stops the 5v trying to charge them when the game is on

The diode can be removed if you felt the need.

Red line is the Jumper and the cross is the diode to remove

[ddstoys]

This can also be done to williams system 3 and 4 Cpus ill try a get my hands on some to show what difference need to be made

[goodolddays]

Top tip Daniel 

Many thanks for taking the time to post this

Cheers
Dave