BuMPing this because two months ago I was moving things and oh crap, I forgot I still had this! >_>
So testing found the voltage rails were stable, the photodiode was detecting "something" and when I poked at all the capacitors I could reach with a Capacitor Wizard they were mostly reading fair but many of them are bipolars so I don't immediately have replacements readily available.
I made the bike inner tube behave and with no less than two different remote controls I can now say the player is completely functional, except for it
still will not lock onto a disc and display anything. There is a test point for indicating a focus error condition and that doesn't seem to be indicating a problem.
At this point I have not seen another 7820 to compare with or buy that was less than $400usd, which is crazy money for untested equipment and these are not the kind of things you want shipped through USPS these days because they are so incredibly heavy. The best I can offer to anyone is all the service documentation is still up on Archive.org and I can break down what my problem is into a video -
https://www.youtube.com/watch?v=DHCD0MMAPUM - but otherwise I'm in serious need of help because I'm stumped. I have been told twice now from the arcade people that the power is a must-do for recapping but when asked "how" they won't answer. They didn't even dodge the question. They just dropped the advice and never replied agian. All PSU wiring is stake wrapped and soldered and going back to the beginning the PSU lives beneath the optical deck, so somehow they were pulling that off and reinstalling it and then being able to align it but again.