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Repair Log - Defender

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The PCB

When the game was powered up, the initial settings would have "?" characters in them. Replaced the CMOS RAM with a new 5101 CMOS RAM. I also replaced the original battery holder (prone to failures) with a lithium battery holder.

The Power Supply

The game kept reporting RAM failures and cycling through the rug test. And then sometimes it would work. This wouldn't happen when I took boards to my test bench, so I figured it had to be the power supply. However, when I tested the power supply, all the voltages were there. Then I re-tested, and found that -5 wasn't there. It turned out to be a cold solder joint. Reflowed solder to the joint and all was well.

I installed a Williams power supply repair kit from Bob Roberts as preventative maintenance. I also replaced all the original Williams "push the wire down" terminal housings with new Molex crimp-style terminal housings. They're just so much easier to deal with.

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Last Modified: 12/07/01