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A1418 | EMC 2889 | Late 2015 | 1.6 GHz dual-core Intel Core i5 or 2.8 GHz quad-core Intel Core i5. Released October 13, 2015.

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No power. LED 1,2,3 flash 2-4 seconds and turn off, and stay off

Hi I got a iMac 21.5" late 2015 A1418 which does not turn on, no power. Opened it up and plugged it in good outlet. Then, Logic board LED light #1 and #2 and #3 flashes green two or three times and turns off. After these flashes (and off), no LED lights will come on whatsoever, unplug and plug, press power button, etc.... nothing else will happen, no green LED whatsoever.

So I thought the power supply unit is bad. Ordered one and install it correctly. After installation, first time I plugged it in, the logic board LED light #1 and #2 and #3 flash green, two or three times, and turns off, and will stay off. After these, same as original power supply, nothing will happen.

So I returned the power supply and put original power supply back in and left it for a week. Then when I try it again, same thing happens, LED light #1 and #2 and #3 flash and turn off, then nothing will happen.

I can not find the answer from Apple diagnostic LED for such symptems.

Is it (1) power supply unit, or (2) logic board gone bad, or (3) other?

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Can you give us a bit more background.

Was the system plugged into a good surge suppressor or UPS? Did you have any lightning storms or major weather (power surge).


I don't know how it happened. Bought it this way and try to fix it.


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Soluzione Prescelta

Let’s assume the system got hit by a lighting strike or power line surge. Even though you might not see physical damage internally enough voltage can jump the power supply onto the logic board killing both.

At this point I think you’ll need to do a detailed inspection of both sides of the logic board looking for any signs burnt chips or the little SMT components have shifted.

Hopefully you don’t spend to much on this system as you will likely need to get the logic board repaired or replaced.

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jjjzzz65 sarà eternamente grato.
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