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Hi guys, I have this old iMac (A1224, 20”) which looks very good but there’s no sign of life from it. I disassembled it and connect the cord to it and - #1 diagnostic LED is turned on, that’s it, nothing else. Of course I tried to turn it on but the only sign I watched is the fan (left on) moving a bit when I click on the power button - but that’s it (I can add a video of it - it barely moving). So the power button is okay, but I’m not sure what is causing the problem - it can be the power supply or the logic board? or something else? I want to give it back to life - but I’m not sure what can I do with it right now and if it’s even worth it…. Thanks! Update (09/16/2019) As I saw in here: A1224 Mine probably has the E8135 CPU (on the bottom there’s sticker says 2.66) - which should to be the best option available to my system, is that correct? And according to the website above - mine is also a iMac 9,1 model - So if everything will work after the PSU replacing - I will be able to make the rest of the upgrades (SSD, RAM and OS) in order to bring it back to life! :) Dan, you’re great! I will update when I’ll get the part I need - Thank you very much! Update (10/23/2019) Same issue after replacing to a new PSU Hello Dan, I finally got the PSU and it looks good, but after I connect it inside with all the cables, it turn on the #1 LED but the issue remain the same, so the fan is barely moving one time only when I click on the power button. I assume that my original PSU is just fine but I’m wondering if my problem is larger than what originally thought and if it’s worth fixing it. I’ll glad to hear any help. Thanks!

From your description it sounds like your power supply has failed. you’ll need this part iMac Intel 20" 2.66 GHz EMC 2266 Power Supply and here’s the guide iMac Intel 20" EMC 2266 Power Supply Replacement Diagnostic LEDs The iMac has built-in diagnostic LEDs on the main logic board that can help you to troubleshoot the computer. The LEDs are located to the right of the battery (see photo below). LED #1 - Indicates the trickle voltage from the power supply has been detected by the 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 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 - Note: This LED is not used on systems that have integrated graphics, which includes all configurations of the iMac (20-inch, Early/Mid 2009). LED #4 - Indicates 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.

ariec 7 makes me wonder if LED 2 does not come on because your computer does not come on. LED #2 - Indicates 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. Check this with emphasis on #5 and#6

  1. Power ON system. Verify if there is any indication that the system has powered up (fan rotation, hard drive or optical drive noise, backlight turns on). Yes The symptom is powering up. Jump to Won’t Start Up. No Go to step 2.
  2. Remove front bezel and locate diagnostic LED’s on logic board. Plug power cord into system. Verify whether diagnostic LED #1 turns ON. Yes Trickle voltage being supplied by power supply. Go to step 3. No Replace power supply.
  3. Press power button while monitoring diagnostic LED’s. Does diagnostic LED #2 turn ON and remain ON after pressing the power button? Yes Power supply functioning and logic board detects supply voltages. Jump to Won’t Start Up. No Go to step 5.
  4. Disconnect power then remove power supply and carefully inspect AC inlet and DC output connectors and cables for damage or poor connections. Were any problems identified? Yes Replace damaged part. No Go to step 5.
  5. Inspect power button and verify that it is properly connected to the logic board. Yes Visual inspection OK. Go to step 6. No Reconnect power button. Replace rear housing (which includes power button) or logic board if damage is present.
  6. Disconnect power button from logic board and verify continuity between two pins when power button is pressed. Yes Power button is functioning correctly. Go to step 7. No Power button faulty. Replace rear housing which includes power button.
  7. Press power button and verify whether system turns ON. Yes Power supply is functioning. If system still does not boot jump to Won’t Start Up. No Replace power supply. Retest. If No Power symptom persists after all steps have been followed use Minimum Configuration troubleshooting to proceed. Try disconnecting the hard drive, optical drive, AirPort, and Bluetooth modules to determine if one of them is preventing the power supply from functioning. Let us know what 820-XXXX your logic board is. There may be a way to try to use power-on pads to see if it comes on.