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

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iMac won't start, not sure between power source or logic board...


I have an iMac 20" A1224 Core 2 Duo 2 GHz with 2 Gb RAM, 3 weeks ago my 250 Gb HDD went dead on me... only thing iMac did was give a black screen with a few lines of code, tried everything, would not boot. So, after kicking myself for not having a decent backup, I got a TOSHIBA 500 Gb HDD... and looked up the guide for HDD change.

So I came home and pushed on the power button and... fans started, got gray screen... then I waited for the Apple logo, but it went dead on me... so I looked for how to check the power source and learned to do it by looking at the 4 LED lights on the logic board. I'm pretty sure it's not power, because LED#1 is on all the time, but when I push on the button: fans try to start (they spin a few times), LED #1 stays on, but then LED#2 blinks for a split second and the iMac does nothing... I mean it stays off.

Could anyone please help me? I currently live in a island in the Caribbean and it's going to cost me more to get my 20" iMac to a technician, then it cost me to buy it in the first place!

Do I need to check any further the power source?, do I need to change it?, is it the logic board?, how can I be sure?

I'd really appreciate it!

Answered! View the answer I have this problem too

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Use a multimeter and test the output of your power supply.

LED #1 Indicates that the trickle voltage from the PSU has been detected by the logic board. This LED will remain ON whenever the iMac is connected to working AC power. 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 PSU is faulty. LED #2 Indicates that the main logic board has detected proper power from the PSU when the computer is turned on. This LED will be ON when the computer is turned on and the PSU is working OK. LED #3 Indicates that the computer and the LCD 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 enters Energy Saver mode

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Hello mayer, is it possible that if the logic board is dead that LED #1 will not come on even if the PSU is good? Thank you!


The #1 LED will be on even if the PSU is dead. It only indicates that it is getting power, not that it is working. The PSU is 10 times more likely to fail than the logic board.


Just a clarification please: did you mean to say the "The #1 LED will be on even if the logic board is dead?" and not PSU? Otherwise that would contradict "The LED will turn off only if the AC power source is disconnected or the PSU is faulty". Thank you once more.


I meant what I said. Reread what you think it contradicts. That statement says OFF.


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