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Model A1419 / Ende 2013 / 3,2 und 3,4 GHz Core i5 oder 3,5 GHz Core i7 Prozessor, ID iMac14,2

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Diagnostic LED - what order?

Hi -

I'm trying to figure out the sequence of the LED's. Is #1 at the top, looking at the computer the right way up, or at the bottom? I ask because the bottom one is lit while none of the others are, but it would seem odd for only LED 4 to be lit. The computer does nothing upon pressing the start-up button. It also makes a slight buzzing sound from the power supply when plugged to power. Any suggestions would be most appreciated. Thanks

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hi,

On my iMac, only leds # 1 and # 2 are on

I think that it is the motherboard which is out of order and which must be changed

What do you think?

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Gewählte Lösung

As @mayer said iMac 27 late 2013 won't power on

"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

-mayer

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Is LED 4 at the top or the bottom of the vertical row of 4 LED's? In the 2013 model they're vertically arranged and only the bottom one is on, but I'm not sure if that's LED 4 or 1. According to your explanation above, it should be impossible for only LED 4 to be on. Thanks for any input

von

It's #1 and you have a power supply issue.

von

@hughprobyn - I added the labels for the LED's for you

von

Thanks very much. I guess it's time to order a new power supply.

von

@danj where is the location of the LEDs I'll make a guide using existing pictures because I dont own a imac

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Based on first-hand experience, what’s the consensus for the scenario that’s being discussed here?

LED 1 is on, but none of the rest light up when pressing the power button

A) bad power supply

B) bad logic board

C) other

I’m serious. Because there’s no point messing with a replacement logic board on a 10 year-old iMac. I’m borderline even if it’s the power supply. Please reply, y’all.

Thanks.

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@wellconnected all LED 1 really does, it tells you that your AC power is plugged into the power board. MY first suspicion on this is always the power board.

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Hugh Probyn wird auf ewig dankbar sein.
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