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

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Mid 2017 iMac No power -Replaced Power Supply with no luck - Now what?

I’ve had other iMacs with the no power issue that were resolved by unplugging the power cord and then plugging back in, but when this one continued to have issues, I replaced the power supply…. still no power - no sound, no fan, nothing.

Are there any out there with similar issues that have been resolved that can suggest a next step? I’m thinking Power Button…

Thanks for your input.


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Bu iyi bir soru mu?

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Same thing with me. I replaced everything even the logic board. Nothing. I’m baffled and angry at the same time!


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The LED’s are telling us we are still having a power issue! Within the logic board is some VRM logic which I’m suspecting has failed.

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You’ll need find someone with the needed skills and tools to repair your logic board or you’ll need to replace it.

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What does the onboard diagnostic LED’s telling you?

Block Image

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.

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Puan 1

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Hi Dan,

Thanks for taking the time to post. I appreciate your help.

Here's what it looks like:


LED 2 Blinks with LED 3


Also, the FAN spins then fails.


Did you read them from top to bottom? Apple reads them from the bottom up!

Which would mean:

LED1 - On

LED2 & LED3 - Blinking

LED4 - Off


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I have no power not a thing is happening not even leds are on

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Puan 0

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@i2cg - in that case you need to start at the AC power outlet checking its voltage, then test cord, the. The AC I put of the power supply. If you see power to the power supply it’s safe to say the power supply has failed.


I’ve tested the power cord I’ve changed power supply I’ve tested the board for power and there is voltage but not one thing works. I’ve tested the power button, fine. Should i be looking for a new board


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