My iMac will not turn on?

joshchansky, first try what Apple suggest. "

The iMac (17-inch Late 2006) has three built-in diagnostic LEDs and a front power-on/sleep LED on the main logic board that can help you to troubleshoot the computer.

To Access the Diagnostic LEDs:v

1. Follow the take apart instructions to remove the RAM access door, front bezel, and lower EMI shield.

2. Locate the SO-DIMM slot and LVDS video connector. The three diagnostic LEDs 1, 2, and 3 are located to the left of the battery and under the SATA cable. Note that the LEDs are marked 1, 2, 3 from left to right, as show below. An additional front bezel LED is located in an opening at the center of the right speaker, as shown below.

LED #1

• Indicates that the trickle voltage from the power supply has been detected by the main logic board. This LED will remain ON whenever the iMac is connected to a working AC power source. 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 source 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 LCD display are communicating. This LED will be ON when the computer is turned on and video signal is being generated.

Front LED

• Indicates that the computer has power but no video signal (e.g., the computer is starting up or the display has entered Sleep mode, turning off the video signal). This LED will pulse when the entire system has entered Energy Saver mode.

Power Issues

No Power

The iMac (17-inch Late 2006) will not turn on. The display remains black and there are no sounds from the fans or drives.

1. Verify the power outlet is good. Plug a different device into the socket to ensure there is power, or plug the iMac into another outlet. Does the iMac power on now?

Yes: Resolved. Bad outlet.

No: Go on to the next step.

2. Check the power cord. Use a known good power cord. Does the iMac power on now?

Yes: Your power cord has failed. Replace the AC power cord.

No: Go on to the next step.

3. Check the connection of the power cord on both ends. Verify that the power cord is securely plugged into both the AC outlet and back of the computer. Does the iMac power on now?

Yes: You may have a loose fit to your power cord. Replace the AC power cord and test.

No: Go on to the next step.

4. Follow instructions in the General Information chapter to reset the SMC. Does the iMac power on now?

Yes: Issue resolved.

No: Go on to the next step.

5. Remove and reinstall the SO-DIMM memory modules, located in the bottom of the

computer. Does the iMac power on now?

Yes: Issue resolved.

No: Go on to the next step.

6. Remove the RAM access door, front bezel, and lower EMI shield to gain access to the three diagnostic LEDs. See “Diagnostic LEDs” in the General Information chapter for complete instructions on this procedure.

7. Plug the power cord into the iMac and the power cord into the AC outlet. Check to see if LED #1 is On or Off.

LED #1 is On: This indicates that the power supply is getting good power from the AC outlet.

Go on to the next step.

LED #1 is Off: This indicates that either the power inlet assembly or the power supply should be replaced.

8 Press the power button. Check to see if LED # 2 comes On, comes on momentarily, or stays Off.

LED # 2 is On: The Power Supply is functioning. Go on to the next step.

LED # 2 comes on momentarily or stays Off: Replace the Power Supply.

9. At this point in the Power On process, you should hear a boot chime and see the front LED on the computer light up. When the main logic board and LCD panel communicate to deliver video, the front LED should go off, and LED # 3 should be on. Does the Front LED go off?

Yes: The LCD and main logic board have communicated. If there is no picture on the display, follow “No Video” troubleshooting.

No: Your logic board is not communicating with LCD panel. Go on to the next step.

10. Check to see if LED # 3 is On or Off.

LED # 3 is On: The logic board is communicating with LCD panel. Follow “No Video”

troubleshooting.

LED # 3 is Off: The logic board is not communicating with LCD panel. Reseat the LVDS cable and test again. If the issue persists, replace the main logic board.

To reset the SMC on an iMac (17-inch Late 2006)

1. From the Apple menu, choose Shut Down (or if the computer is not responding, hold the power button until it turns off).

2. Unplug all cables from the computer, including the power cord.

3. Wait at least 15 seconds.

4. Plug the power cord back in, making sure the power button is not being pressed at the same time.

5. Reconnect your keyboard and mouse to the computer.

6. Press the power button on the back to start up your computer.