My iMac dosent work at all

@a1312 check on some of the basic things first.

Here is the sequence for the No Power check

Symptoms

No Power

• No power

• No fan spin

• No startup sound

• No image on external display

• No hard drive or optical drive activity

• Caps Lock LED on wired keyboard doesn’t light when pressed.

Quick Check

1. Verify power source.

2. Verify power cord.

3. Listen closely for signs of activity from system including: rotating fans, hard drive or optical drive activity, startup sound, etc.

4. Disconnect all peripherals.

5. Reset SMC.

Let us know what you get

Resetting the System Management Controller (SMC)

The System Management Controller (SMC) is a chip on logic board that controls all power functions. If computer is experiencing any power issue, such as not starting up, not displaying video, sleep issues, or fan noise issues, resetting SMC may resolve it. To reset SMC on an

1. From the Apple () menu, choose Shut Down (or if the computer is not responding, hold power button for approximately ten seconds until it powers off).

2. Unplug the computer’s power cord.

3. Wait 15 seconds.

4. Attach the computer’s power cord, making sure power button is not being pressed.

Note: If you press the power button while inserting the power cord, the iMac will enter a mode in which the fans run at full speed. For more information, refer to Apple Support article TS1433: iMac: Fans run at full speed after computer turns on 5. Wait 5 seconds, then press the power button to turn on the computer.

Next you want to check your Diagnostic LED's

LED #1

• Indicates that the trickle voltage from power supply has been detected by main logic board.

This LED will turn ON when you connect the iMac to a working AC power source. The LED will remain ON as long as the computer is ON or asleep.

• When computer has been correctly shutdown, the LED#1 behavior may differ:

• - If a startup event is scheduled in System Preferences/Energy saver, LED#1 will stay ON after a correct shutdown,

• - If no startup event is scheduled in System Preferences/Energy saver, LED#1 will turn OFF and will stay OFF as long as power cord is kept connected and AC power source is present.

Disconnecting the power cord and plugging it back will turn back this LED ON , even if computer is still off.

• After disconnecting and reconnecting the AC power source, this LED could remain OFF if the AC power source is missing or disconnected , if the logic board is disconnected from the power supply or from the AC receptacle, or if the power supply board is faulty.

LED #2

• Indicates that computer is turned on. This LED will be ON as long as computer is turned on (but is not asleep) and power supply and voltage regulators are working correctly.

LED #3

• Indicates that computer and video card are communicating. This LED will be ON when computer is communicating properly with video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the backup battery (on back of logic board) may need to be reseated, or the video card might be installed incorrectly or needs replacement.

LED #4

• Indicates that computer and LCD panel are communicating. This LED will be ON when computer is turned on and video signal is being generated. If LED#4 is ON and there is no image on display, then the LCD panel, the LED backlight board, or the cables between LCD and logic board or backlight board might be installed incorrectly, or need replacement.

My suspicion is a bad power supply. See if you get this

LED Startup Sequence

LED #1 = Power available.

If no LED is visible:

• First disconnect the power cord from computer, then reconnect it to reset the LED status, in case computer was correctly shutdown and AC was kept connected since

• Verify AC source

• Verify known-good power cord is connected

• Verify cable connection between AC inlet and power supply

• Verify cable connection between power supply and logic board

• Verify power supply

My suspicion is a bad power supply.