Model A1224 / Mid 2007 and Early 2008 / 2, 2.4, or 2.66 GHz Core 2 Duo processor

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My iMac will not turn on. Is power supply out?

After a couple of power bumps to our home's system, and power was restored, all home electrical panel breakers were still in the on or untripped position. The 6 outlet power strip, my iMac was plugged into, was still on, again, untripped, but my iMac will not turn on. I have tested the power cable from the power strip to the iMac, it's OK.

My first thought is blown power supply. Second, damaged motherboard. Need info. on diagnosis procedures, repair, ect.

Thanks! JMP

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John Poen, what are the last three digits of your serial number. That will help us to properly identify your computer.

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Here's a diagnostics manual. Very comprehensive. Sorry if it's a couple years late, but maybe someone else has the same problem.

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wow. worked for me. I thought I was dead. thank you for the simple fix

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Greetings! i would like the guide trouble shoot an iMac 1311 (2011) with similar history (lighting stroke), router burnt, machine connected only to ethernet cable not wall power cable. No power whatsoever. Thx!

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John Poen, here is the trouble shooting guide from Apple. It should help to narrow it down.

Diagnostic LEDs

The iMac (20-inch 2007) has four built-in diagnostic LEDs on the main logic board that can help you to troubleshoot the computer. The four LEDs are located to the right of the memory slot, under the hard drive data cable.

Block Image

It may be necessary to carefully remove the hard drive data cable to view the LEDs.

Block Image

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 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.

The Computer 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 memory access door and front bezel to gain access to the four 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 the computer is not detecting AC power. If both the AC outlet and the power cord are good, replace the AC/DC power supply. If the issue persists, replace the AC line filter.

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 that LED #1 and #2 are On. Do you hear a boot chime?

Yes: The power systems of the computer are working correctly. See “Troubleshooting No Video” in this chapter.

No: The logic board is not passing the Power-On Self Test (POST). Replace the SDRAM with known-good memory and test. If the issue persists with known-good SDRAM, replace the logic board.

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sir no one of the our led was lighted what does it means? thanks

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Ernesto Albite, check the power supply.

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" LED #1 is Off: This indicates that the computer is not detecting AC power. If both the AC outlet and the power cord are good, replace the AC/DC power supply. If the issue persists, replace the AC line filter. "

sir thank you for your response....

sir, where can I find the AC Line filter?

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I check the output voltage of the power supply , there is only 12volts in the six wires. the first 3 is for negative and the other 3 is for negative.

there is another six small wire includes the switching for power on button. Is there another output voltage other than the 12 volts? please sir help me thanks..

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Most Helpful Answer

Hi John !

There are several things that you may try to fix your problem. At 1st, try to plug it somewhere else. Then, try resetting your SMC. To do that :

  • Unplug your Mac
  • Press the power for (at least) 5 seconds while unplugged
  • Plug it in again then wait approx 10s before trying to start it.

You may know that power supplies on Macs are pretty strong. I'd say that your MotherBoard is dead if the previous reset does not work. You may test each of these components before replacing one (of mabe them both).

Hoping to have helped you,

Don't forget to give us some feedback !

Vincent

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Thank You! This brought my I-Mac back to life.

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informative, will need to have imac checked out.

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Slight powewr surge at the house last night. iMac dead this morning. Thanks for a quick and helpful way to keep me out of the Apple Store! Was dreading having to replace the power supply on my mid-2007 iMac. Had tried plugging and unplugging the iMac with no luck. The SMC reset did the trick! THANK YOU!

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I worked thanks.

Thought I was looking at a power supply problem. This worked and to bad I didn't see it before for I replaced the iMac. Now I have two of them. What to do need a network maybe?

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This was awesome feedback. We are installing solar panels and they disconnected our electric power here at my home, without giving me enough time to turn my computer off and unplug from the wall. Then it would not turn on, i tried everything and then called MAC, they never told me to do the steps you have recommended instead, I was told to bring it in to mac and most likely it was my mother board that needed replacement which meant $$$$$! I decided to do my own searching and found your feedback. I am so happy I did, I tried your steps above and unplugged it from the unit and hit the power button for at least 5 seconds and then replugged it and "IT IS ON" thank you! I can't thank you enough for posting this advice. You saved me a drive to the MAC store and big $$$$.

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