Defender Upright restoration

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Received a dead Defender upright ($200). Needs a new marquee and the control panel has some cig burn. Power supply appears dead. Rebuilt it using a William Linear Power Supply Rebuild Kit. Powers up, white screen.

Swapped the CPU board from my cocktail, and it comes up. And plays. Monitor is super bright, I turned down all drivers on the monitor all the way and it's still a bit bright.


Trashed the decoder PROM 3 by plugging it in backward. Burn 2 new decoders on 2716s, and wire the board appropriately.


Get out the logic probe. No reset. Deal with it later.


Install new transistors in Q5-Q12. Same trouble. The 7411 AND doesn't appear to be funcitoning correctly. Got the board to boot by shorting 3C (which works correctly) to 3Y. Will replace this chip.


After tracing this all over the place, I got really lazy and just soldered a jumper from 3C to 3Y on the 7411. The thing works fine now, and I intend to fix it "for real" but knowing human nature this will stay this way forever.

Thanks to Mark Spaeth, Steve Weinrich, and "Fred" for their help in troubleshooting.

You can contact me through this minimalist contact form if you wish.
kk's entire collection