Chosen Solution
My thunderbolt display has been flakey for the past few years with the backlight intermittently deciding to not come on. I have previously been able to resolve this issue with numerous bouts of unplugging it and plugging it back in but it finally decided to not come back to life this week when I need it most for telework. Based on advice in prior posts from @danj , I replaced the logic board to no avail. Upon teardown, I did notice the left bottom backlight connector is loose so wondering if replacing the LCD panel would be the next step? Would the whole screen not work if just one backlight connector is bad? Of note, the display works (no backlight) and all accessories work fine. Thanks in advance for any replies!
Its been awhile since I’ve dug deep into a 2011 iMac/TB displays. Needing to fix the mating connector breaking free. It’s a big job to dig into the display assembly to properly fix this. Here’s a good vid that gets into one possible repair direction other than replacing the display: Apple iMac 27" Dark Side Screen Failure - The Manufacturing Fault Apple Will NOT Admit!! When I see the loose wires I just replace the display as its just easier. Double check the label on the display it should read LM270WQ1 (SD) does it have (B3) or ‘’(E3) for the last digits of the LG # If it is here’s one source for the panel 2011 27” iMac 27" LCD Display Panel, Apple P/N 661-6615, LG # LM270WQ1 (SD)(E3) The correct part: 27" Thunderbolt Cinema Display LCD Panel, Apple P/N 661-6028, LG # LM270WQ1 (SD)(B3)
fixed 4 of these, problem is poor lead-free solder on the LED bar connector failure with heat+age. Resoldering did the trick for me. Here are the directions but does require taking the entire LCD panel apart which is quite fragile. https://drive.google.com/file/d/13GqPCJh…
