Model A1419 / Late 2013 / 3.2 & 3.4 GHz Core i5 or 3.5 GHz Core i7 Processor, ID iMac14,2

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Changed HDD, Backlight Stopped Working

Hello, I have an iMac Intel 27" Late 2013, Core i7 3.5GHz. I followed a guide to take the hard disk out and install a new one. It was quite straightforward and I used another hand as well so that did the trick.

I seriously acted extremely kind towards cables as I was already freaked out but unfortunately something went wrong. Backlight is gone. I used a flashlight and saw that the stuff is still going on in the background yet no backlight as I said. I connected the iMac to an external display and everything works perfectly there. What cable/part might be the issue? How to check it?



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Sounds like the display power cable was not seated correctly or the cable its self is damaged. Review Step 18 in this guide: iMac Intel 27" EMC 2639 Display Replacement.

I would start there. If it looks OK then I suspect the fuse links or LED driver logic on the main board is damaged. Did you use a ESD wrist strap that was correctly grounded?

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I rechecked the cables yet they seem to be in place. No I did not use ESD wrist strap unfortunately. As you mentioned it now, I see that might be a problem. At this point, let's assume the damage is done, what would be the best approach? Ship it to Apple, or replace it myself with proper equipment?


It turns out you were right. Main board is damaged. At this point I believe it is due to static electricity as I worked unprotected without any wrist strap.


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I had a situation with a 24" iMac where after replacing the hard drive, my display did not work correctly. Tried everything, including reinstalling OS X. Nothing worked. Took it to the Genius Bar. The Genius reset the PRAM/NVRAM & corrected the issue. You might want to try resetting the NVRAM.

Good luck! Hope it helps!

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Thanks for the info.

I checked the article and did a NVRAM reset and it did not work.

It turns out that the main board is done...

They indicated I managed to partially burn it :D Don't know how I succeeded though. The first theory with the static electricity sounds plausible as I worked on carpet with no protection yet I have been repairing/assembling PCs/Macs for more than 10 years with no such issue... Dan in his post also indicated the main board might have damaged and I confirm that; the led port and surrounding area is burnt.

So let this be an example to the ones who wishes to assemble/disassemble a newer iMac. And I suggest iFixIt to add an anti-static wrist band or some similar item to the guides, just in case...

Thanks for all your help!


I have the same problem with an iMac 27. i tried adding an SSD and since then no backlight. After checking cables, i bought another LCD display, but the same problem, then i bought another motherboard, and still the same problem. now i have no idea how to solve the problem.


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Check the LVDS cable, or the DisplayPort cable, as it is called otherwise. It was the problem for me, although everything seemed ok. I had to put the cable under microscope to find out that one of the pins was missing (the first one). Although the display has a power cable for the LED of the LCD, if the LVDS cable won't connect the first and last pin, it won't light up the LEDS. I found out the hard way, after changing 2 displays and two motherboards. Check the picture

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