Recent content by denikar

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Selling one of my spare Defender CPU boards and one ROM board. Both boards are tested and working as of 19Nov2025. CPU board: Dynamic RAM upgraded to the more reliable 41256 (5V) RAM. Also the board has been modified to only accept 5V RAM. High score RAM replaced with non-volatile RAM (no...

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Defender ROM board FPGA

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Still available.

Still available.

Metal PCB mounting plate from a Williams Defender. Includes standoffs, volume pot, and brackets for sound board as shown in image. $60 shipped.

Tube still available.

This turned out to be a K7000 B+ regulator issue. B+ would start off fine at +123V and gradually rise until HV shutdown. The voltage did not always rise enough to HV shutdown.

It is Taco Tuesday and they are still available.

Anyone know the story behind the jumper (or lack of) on pin 7 of IC 3A (7486 quad logic XOR gate) on Defender CPU boards? The trace to the left of the IC is floating without the jumper, meaning the IC has no ground connection, so the jumper is definitely needed. However I don't see it on the PCB...

Does JROK not make these anymore?