Chosen Solution
Got this imac a couple of years ago, and it had a dead screen. Wasn’t a problem, I just used an external monitor. I don’t want to use the external anymore, so I bought a replacement panel - LM171W02 (TL)(B2). Popped it in, and it all fired up as it should, except there’s a strange coloured “noise” going on in the blacks and whites. All the blacks are coming up with a red, pixellated snowy noise, and whites have the same but blue. I’ve tried various different colour profiles, changed the contrast in universal access, all of which just made it look worse. I bought a replacement LVDS cable, which hasn’t made any difference, and examined the connector on the logic board, no issues there either. It still works flawlessly on an external screen, so I’m discounting any hardware issues with graphics system or logic board. This has me stumped! Here’s a few pics https://www.dropbox.com/s/4ksrkyl30g0e5j… https://www.dropbox.com/s/3wjgx9ed5buryo… https://www.dropbox.com/s/zywgle00iq65xo…
I think it is the ram. Open up the ram bezel, remove the ram by pushing both metal ram locks up and towards each other and remove the ram. Lightly apply some wd-40 on both ram slots and on the gold puns on the ram cards, then reinsert the ram.
