Posted by Drew Rudman on May 16, 2013

Joust & Defender Battery Kit Upgrades

About 6 years after I bought them, I finally got around to installing Lithium battery upgrade kits into my Joust and Defender systems. Most Williams systems of this era were equipped with a 3 pile AA battery pack to maintain system configuration setting and the high score table. The issues with this approach are manyfold, not the least of which is the relatively short life of AA batteries and their penchant for leaking acid, which naturally will leak onto your main CPU board and do all kinds of damage.

Many years ago, the great Bob Robert’s decided to tackle this issue and developed the first ever, Williams Lithium Battery Conversion kit. While Bob no longer appears to sell these kits, they can be found elsewhere.

Joust was up first. I pulled the CPU board from the system and it appears to be in great shape:


The batter pack was in decent shape as well, although a previous issue had required me to solder a jumper wire from the left-most battery post to the tracer on the back of the board.

The upgrade required me to desolder the existing battery pack and then install the new lithium battery holder and a jumper wire. Desoldering the existing battery pack was more difficult than anticipated since I could only remove part of the existing solder with the tools I had at my disposal (I guess my de-soldering iron is not the great). I ended up breaking a few of the pins that solder the pack to the board, but since I had no plans to reverse this process, that was OK.

Installing the new kit was a snap:


The only issue I had was that the kit was purchased so long ago that the supplied CR2032 battery was only putting out about 2.4V so I had to purchase a new one. Also, oddly, the kit did not include any instructions and was bundled with a resistor, which I assumed was to be used to jumper the bottom two solder joints but Bob’s web instructions recommended using a straight jumper wire, which I did. The conversion worked perfectly and hopefully the lithium battery will give me years of solid performance and little to no danger of an acid leak.

With the Joust system converted and tested to be working properly, I performed the same upgrade on my Defender system. The CPU board for Defender was also in great shape:


with some minor mods to the standard battery pack to improve the connectivity between the battery posts and the solder points on the CPU board:


Desoldering the battery kit once again proved difficult, but with the lessons learned from the previous Joust conversion, took about half the time. Installation of the lithium kit was quick:


Both conversions worked flawlessly the first time the systems were fired up and I’m looking forward to not having to replace the batteries on either unit for quite some time.


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