Chosen Solution
Hi, My iMac is connected to an UPS and I had shut it down last friday before leaving on a business trip. Once back home, I tried to power it on and it simply wont :( When I hook the power cord to the socket(both UPS and direct), I hear a buzzing sound from inside the iMac. Once I press the power button, I hear the startup sound and then it powers off. Subsequent power button presses does nothing and also I dont hear the buzzing sound until I physically remove the plug from the socket and reconnect it. I removed my 3-party purchased RAM and is still the same. Please help solve the problem :(.
Remove the Frame. Plug in and check what you’re getting on the LEDs. Diagnostic LEDs are to the right of the RAM slots (this may be covered by a piece of black electrical tape extending up from the bottom edge of the logic board). Ple4ase let us know your results before buying anything as #1 should be on even if the power supply is bad. See if you can discern where the noise is coming from. LED Startup Sequence LED #1 = Power available. If no LED is visible: • Verify AC source • Verify known-good AC cable is connected • Verify cable connection between AC inlet and power supply • Verify cable connection between power supply and logic board • Verify power supply LED #1 + LED #2 = Power available, and system is powered on. If second LED is not visible when power button is pressed: • Verify power button connection to logic board • Verify power button functionality • Verify cable connection between power supply and logic board • Verify power supply • Verify logic board LED #1 + LED #2 + LED #3 = Power available, system is powered on, and video card found. If third LED is not visible after power on: • Verify that MXM video card is seated properly • Verify logic board
