What does flashing LED2 mean?

[zataralos]

have an iMac 2017 21.5 4K that won't boot up. LED1 is solid green when plugged in but LED2 flashes on and off every 5 seconds. Power button does nothing?

Any ideas?

 

[TwoH]

When the LED 2 flashes, my first instinct is always the RAM.

 

[DeltaMac]

If you hold the power button for about 5 seconds, does the #2 LED go out?
#2 LED is (usually) to indicate that there is power to the logic board (the system is turned on.)
The flashing may indicate that the power supply can't turn on for some reason (try replacing the power supply now)

 

[zataralos]

If you hold the power button for about 5 seconds, does the #2 LED go out?
#2 LED is (usually) to indicate that there is power to the logic board (the system is turned on.)
The flashing may indicate that the power supply can't turn on for some reason (try replacing the power supply now)

yes - holding down the power button made LED2 go off. Question - since LED2 flashes initially and is located on the logic board, doesn't that mean logic board is getting some power and the PS is good? Should I be looking at the logic board for shorts?

Thanks, that first step was very helpful

 

[DeltaMac]

#1 LED is ALWAYS on when power is connected, and indicates that the power supply is at least connected.
#2 LED is (I think) when the power button is pressed and the system begins to power up. The LED indicates that the power supply is activated, and the logic board has received operating power.
Unfortunately the LED continues to blink, so I believe that means that the power supply is not activating.
First choice for the repair is replacing the power supply. I think it is a likely fix.
If not, then it probably gets expensive.

 

[moiimotep]

Hi All,

I have the same issue on my iMac (2017 21.5 4K). LED 1 ON , LED 2 Blinking every 5 seconds...
@zataralos did you fixed your issue? do you have informations ? (RAM or PS ?)

Thanks,