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Model A1419 / EMC 2806 / Late 2014 or Mid 2015. 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (ID iMac15,1); EMC 2834 late 2015 / 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (iMac17,1) All with Retina 5K displays

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iMac internal display works on one computer but not the other.

Hey everyone. My situation is a little complex so bear with me while I set up the background.

I’ve got a 2014 iMac 27” 5k model. It had a faulty GPU, meaning it needed a logic board replacement. I purchased another iMac from eBay that had a good logic board but a cracked display. So I hoped to swap the logic boards in order to have one fully functional iMac.

The swap went well, but when I went to test the display before sealing it up the display didn’t work. This was odd considering it worked before I had done the swap and it didn’t appear damaged in any way. I tried putting on the cracked display just to check if that would work and it did, so it wasn’t an issue with the board.

So then I tried reassembling the board with the faulty GPU (I knew it still worked enough to do some testing). Testing first with the cracked display showed everything worked. Then I tried the old intact display and to my surprise it also worked!

So on the old faulty board, both cracked and intact screens work perfectly. But on the mac with the good board, only the cracked screen works. I have tried swapping them a number of times and I get the same results each time.

Whats going on? Why can’t I get both screens to work on both macs? Any ideas?

Thanks in advance, Floyd.

Images:

1. Display connectors, good logic board

2. Display connectors, bad GPU/logic board

3. Display cables, on the display itself.

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It sounds like you are trying to use different series displays. We will need to know the exact series of each system to verify this.

Plug in your systems S/N's into here EveryMac - Lookup Let us know what you have then we can both explain in better detail what's happening as well as get you aimed at the correct display your system needs.

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@danj Thanks for the reply. Both come back with the same result. Both are Model A1419 (EMC 2806), ID iMac 15,1. Only difference in specs between the two is that one has an i7 and the other an i5.

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In that case that points to the logic boards display connector and the cable to the display. Take a few pictures of the connector and cable end so we can see things Adding images to an existing question

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Ok I've added the images to the main post.

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@Floyd Bromley - Sadly they are not sharp or detailed enough to see things. See if adding some light and get closer. Also try to use larger pixel camera and file.

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@danj I've re-uploaded the images, this time at full resolution. Let me know if that helps or I can try to capture it again.

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Sorry I can't see anything that explains things. At this point you'll need to see if you can find someone locally that can help you.

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@danj thanks for your help anyway.

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Floyd Bromley crwdns2934231:0crwdne2934231:0
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