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Jimmy422

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  1. Out of curiosity, what are your concerns? I left it up and running for a few hours yesterday and a few hours today and it's still been rock solid. So far the only time things get questionable is when you put a CD in, it appears the screen distorts ever so slightly as the disc is read, but that might be normal? I wonder if the CD drive needs a recap as well, it smells like fish when I eject the caddy out of the drive.
  2. Thanks to your post, I FIXED THE ISSUE! Based on your post I had two theories: A. That filter cap is actually bad and causing the input power to the whole board to be messy. B. That melted looking pot that controls the 5v and 12v outputs is dirty and causing issues on those ends. I was able to turn up my soldering iron heat as high as I could and was able to wiggle the old filter cap out. The bottom of it had a little bit of electrolyte leaked on it which pretty much confirmed to me it was shot. I also hit that pot with deoxit. I wasn’t able to move the adjustment screw at all (it’s definitely melted) so I don’t know if that actually did anything to help. I would’ve tested these fixes independently but it’s a pain to keep taking the board out. Either way, one or both of those things fixed the issue! I booted it up and the screen and brightness are perfectly stable now. Even though recapping the rest of the board was a “waste” at least I know that that the caps on that analog board are going to be rock solid for another 27 years. Thanks a bunch for everyone’s advice! I’m gonna go enjoy my LC now
  3. I’m fairly certain the issue is with the flyback. The noise i can hear coming out of the back when it distorts sounds like it is coming from the flyback transformer, although perhaps the issue is being caused by whatever is feeding the transformer. Unfortunately it seems like finding these transformers in 2020 is impossible. I haven’t found one anywhere online. My guess is I’m going to need a working donor board from another LC to fix it.
  4. Well today I replaced all but one capacitor on the analog board. Absolutely no change to the issue. The big filter capacitor was the one I didn’t change out as my soldering iron couldn’t get hot enough to melt the leads, but from what I’ve read online they don’t usually go bad anyways. As i was working i checked again for any cracked solder joints and there’s nothing. There was, however, a potentiometer that looked a little warped (dare I say melted?) in the middle of the analog board. I have no idea what it controls and I don’t have a part number to get a replacement for it, nor would I know what value to tune it to if i got a new one. Could that be related to the issue? I’ve attached a picture if anyone knows what that potentiometer controls. Any more advice would be appreciated!
  5. 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.
  6. So I did reseat the ram, logic board, and analog board sadly with no luck. I set the brightness as low as it would go and it didn’t change anything (and neither did maxing out the brightness, not sure if that means anything?). Also tried another circuit in the house and no dice with that either Here’s a video of the issue in action. You can see the brightness will max out at random and the picture size is all over the place. I guess that very well could be a capacitor issue. I bought an ESR meter so I’ll see if I can find which ones need to be replaced.
  7. Hi all! I picked up an LC 520 off ebay a few weeks ago. I cleaned and re-capped the motherboard and to my surprise it booted up just fine. However, the screen will flicker and distort as it runs. A couple times it has flickered and gone to black, which made me have to reboot the machine entirely to get it back up. I believe I can hear the hard drive spin down slightly when the screen flickers, which makes me think the issue is power related. I took a look at the analog board and all of the capacitors look visually okay - I don't see any spilled electrolyte or bulging caps, nor do I see any cold solder joints on the bottom of the board. The flyback transformer is solidly soldered in place and doesn't seem to have any cracks in it. Does anyone have any advice as to what I should look into to fixing this? Should the analog board be re-capped as well given the machine is 27 years old? (I hope not, because there are a LOT of capacitors!)
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