Chosen Solution
Mid 2011 27” iMac A1312 EMC 2429 My iMac will not power on. When I hit the power button, I hear no chime and no fans. I have already tried unplugging it and holding the power button, then replugging it in. I have tried removing the RAM, dusting and putting it back in. I removed the display and gave everything a good dusting. The far-left diagnostic LED is on and green. The other 3 LEDs will not indicate anything because I can’t turn on the computer. I have tested the voltages on both the power supply and the logic board with a voltage meter from the back. Power Supply Results: Pin 1 - GroundPin 2 through 4 - No voltagePin 5 - 14.78 VPin 6 - No voltagePin 7 - 4.06 VPin 8 and 9 - No voltagePin 10 - 3.63 VPin 11, 12, 13, 14, 15 - approx. 13.5 VPin 16 - No voltage
Logic Board Results: Pin 1 - GroundPin 2 through 5 - No voltagePin 6 - 4.2 VPin 8, 9, 10, 11 - 15.2 VPin 12 and 13 - No voltagePin 14 - 4.2 V
Is it safe to rule out the PSU as the problem here? If it’s not the PSU, what should I check next? Could this be a problem with the power switch? Any suggestions would be greatly appreciated.
Sadly your power supply has failed. Here’s the needed part iMac Intel 27" EMC 2309, 2374, 2390 or 2429 Power Supply. There is additional logic within it that offers the soft power switch function.
I have same problem except moving fan in few seconds when i press the power button. Yesterday i replaced new PSU receving from ALIEXPRESS. The result was successful but today morning my it has same problem when i press the power button. I could not understand what happen on my imac during one night. I frustrated this result… If you have any successful results, Please inform me
