Chosen Solution
Recently my 2009 iMac 27” turned off and the power button does absolutely nothing when I push it. No fans. I push it and no response. First I thought I needed to buy a new power cord to plug into the back of my iMac but someone suggested that the power supply may be bad. So then I took apart the computer and got to the power supply and was wondering if you can take a look at the circuit board to see if this might be the culprit? I noticed a lot of yellow stuff in one section as you can see in the pics.
UPDATE 1 green LED on diagnostic board after I plug in the AC cord
UPDATE 2
Removed Logic Board / GPU
Re-assemble your system, then plug in your power cord. Locate the onboard diagnostic LED’s coverd by black tape in the bottom left of your logic board
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. Let us know what you discover! Update (05/10/2020) Here’s a picture of the logic board power button connection
hi , is there any burn on it where is the yellow soldering grease if yes then power supply faulty
