It’s probably a long shot but do you know if there’s any schematics out there for the LC 520 analog board? It’s a little hard to troubleshoot what’s going where without em.
I pulled the analog board out today and started testing capacitors with my ESR meter. Out of the 10 I’ve tested so far only one had an ESR reading that out of spec (and it was significantly out of spec, so maybe that’s part of the issue?). All the others were all in range. There’s 30+ capacitors on the board so I’ve still got a bit to go, but the bad one is definitely getting replaced.
I also double checked for cracked solder joints and I still don’t see any anywhere. Triple checked the flyback and surrounding areas and it’s all good. I’ll try hitting the pots with deoxit for good measure though.
I have a nice ratcheted RJ45/RJ15/RJ11 crimper as well. I got it at WeirdStuff surplus for cheap. I used it a lot when I worked at a different school campus, but my new work insists on buying molded ethernet cables. I understand the paranoia, but, I did like crimping my own cables and using them. Was pretty satisfying.
If I ever get my own house, I'll make PLENTY use of it wiring up ethernet and phonenet.
Was able to rule out the monitor using a very hacky hack to get some signal directly to a separate VGA. I didn't know how to deal with the grayscale, so I just sent it to green -- and you can see the same pattern shown. So its something on the logic board. I guess I'll proceed with ordering some caps, and see if that fixes anything (but I doubt it)
You'll probably be able to reach Rob Blessin at nextcomputers.org, but if not, I was able to get help from him three years ago at the email address on this site: https://www.blackholeinc.com/specials/contact.shtml and he was very knowledgeable.