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A1418 / EMC 3068 / iMac 18,1 / 2.3 GHz dual-core i5 processor. Released June 2017.

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Black display no image

Bought this from a person who said they attempted an SSD and RAM update and now the machine will not display. It starts, fans spins up but no display. Any ideas on what and how to fix this? Possibly a guide? Thanks

Note LED indicators 1 and 2 on the motherboard illuminate when powered on. With LCD attached LED 3 only briefly illuminates. 4 does nothing.

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The common issues I’ve seen is people either damage the display screen or the logic board display connector. But without opening the system to inspect things I could list a good dozen other possibilities!

Review this guide iMac Intel 21.5" EMC 3068 Display Replacement compare the images carefully for damage and take some pics of anything that looks questionable, post them here for us to see.

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Thanks for the response. Everything looks good, I see no issues with the cables or connectors. The glass is cracked but apparently has been tested on another imac and it illuminated and displayed. I can add that LED 1 and 2 are lit on the motherboard but 3 and 4 are not. From my understanding led's 3 and 4 are communication between the motherboard and the GPU? Perhaps the GPU is cooked?

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@procatjuggler - The LEDs only light up when the internal display is connected. Apple uses a set of extension cables when working on these systems so the display is still connected.


Having a cracked display just tells me this system had some trauma! And supports my concern. I would need to see the system or some good pictures of the damaged display, the cables and there connectors both ends and the logic board.


For reference here’s the display assembly:

> Non-Retina

> 4K Retina


So consider the costs of the parts.

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Hi Dan, I appreciate your expertise greatly! I have uploaded a few images of the LCD and connections. In ammendment to what I said about the LED indicators, 3 does light up briefly when the LCD is attached but does not stay on, 4 does nothing.

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@procatjuggler - Here’s a better description of the 3 & 4 LEDs

LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.

LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.


I’m suspecting the display failed which given the damage doesn’t surprise me. You have the non-retina system. At this point you need a replacement display to move forward.

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