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Pantalla de 27" con resolución de 2560 x 1440 píxeles Conexiones de cable Thunderbolt y MagSafe

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No backlight still after replacing logic board

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!

Contestado! Ver respuesta Yo también tengo este problema

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I guess I stepped in it here! Can you post a few pics of the backlight connector which is loose so I can see it.

It maybe you got a bad part or the power supply has issues. Do you have a DVM to check voltages?

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Thanks @danj ! I uploaded a video of the loose connection in the original post. I have seen in other posts and videos local dimming when one of the connections is bad but unsure if it would kill the entire backlight? I do have a run of the mill cheap voltmeter if needed.

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Did you mangle the case? It looks like someone got inside at some point.

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I just pulled back the foil tape to check if the connections were loose. I do not think the display has ever been pulled apart.

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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)

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@danj thank you so much for assistance! I found a good second hand display that is reasonably priced but don’t want to buy it if the underlying problem is in the logic board or power supply. All other functions work including speakers, webcam, and display so I don’t think it is the power supply. Is there anything I can check on the logic board with a multimeter to see if the backlight control chip is working?

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You lost me ?? Your issue is the connector. Did you watch the vid?

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I watched the video but that loose connection only caused local dimming on one side of the screen. Would it be worth checking anything else prior to shelling out the money for a replacement screen?

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The local dimming is do to the fact there are multiple LED's loosing contact to a bank not the full strip.

Sorry I can't make a silk purse out of a sows ear here ;-{

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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.

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Yep! Love that solder!

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Brandon estará eternamente agradecido.
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