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A1418 / EMC 2833 / Late 2015 / 3.1 GHz Core i5 or 3.3GHz Core i7 Processor. Released October 13, 2015.

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Black Screen but Fan works

So I have the A1418 EMC 2883 iMac 21,5“ Base Model and it stopped working. When trying to turn it on, nothing happens but the Fans spin. When I hold Powerbutton while plugging in, then the Fans spin up in high power mode but nothing appears on the screen.

i get two LEDs on so I tried changing the PRAM battery and changing the CPUs Paste (CPU soldered on and no discrete GPU). But it is still not working. Could this be CPU failure or something else? Where to measure?

Regards

Answer this question I have this problem too

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1 Answer

Here's a breakdown of the onboard diagnostic LED's:

LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.

LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.

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.

Block Image

Sadly, it does sounds like your logic board has failed.

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2 Comments:

So as this is base model. Can I swap out the Logic Board with the one from an better model? If I spent like 200€ on this I would like to upgrade at least. But first I try to reflow the Ram and CPU.

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Your limited to this series: iMac16,2

21.5" iMac 4K Logic boards with SSD option:

∙ 3.1GHz i5 QC, 16GB - Apple P/N 661-02986

∙ 3.3GHz i7 QC, 16GB - Apple P/N 661-02988

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