Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

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Blotched SSD upgrade: Why is my display black?

Following an SSD upgrade using an OWC upgrade kit and thermal cable my iMac's display no longer powers on.

On power up I get a happy start up chime followed by a steady increase in fan volume with only my external monitor turning on. When I run the apple hardware test I get error/fault 4sn/1/c0000008:TL0p--124.

Any ideas what I may have inadvertently broken or misconnected? Is whatever I most likely did easy to repair/replace?

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If your HD was working and you are swapping it out to gain the speed of the SSD you may want to consider putting it back and then add the SSD as a second drive following this IFIXIT guide: Installing iMac Intel 21.5" EMC 2428 Dual Hard Drive Kit. Once installed you can prep it up leveraging the internal HD and then install a fresh copy of OS on it and migrate your apps to the SSD. Once done you can then go into the system prefs and select it as your start up drive. Now with a dual drive you gain the speed of the SSD but also hold onto the deeper storage of the traditional HD. In this case the second drive does not need to be connected to SMC services. This is what I recommend as the ideal setup!

The issue with your internal display sounds like you forgot one of the cable connections. Review this IFIXIT guide to see what was forgotten or mis-connected: iMac Intel 21.5" EMC 2428 Display Replacement. To help narrow down what is disconnected try using a flashlight shining it into the glass at a sharp angle, you should see a faint image of your desktop icons if the backlight connection was forgotten. As you have an external display working we already know the GPU is OK, so that leaves the data cable and the thermal sensor cables.

iMac Intel 21.5" EMC 2428 Display Image


iMac Intel 21.5" EMC 2428 Display Replacement



iMac Intel 21.5" EMC 2428 Dual Drive Kit Image


Installing iMac Intel 21.5" EMC 2428 Dual Drive Kit



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That was basically it. I got ahold of OWC tech support and ended up doing a straight disassembly, damage inspection, reassembly... and everything was working as advertised.


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