Model A1225 / Mid 2007 and Early 2008 / 2.4, 2.8, or 3.06 GHz Core 2 Duo processor

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Only diagnostic led 2&3 lit

I have a mid-2007 iMac 24" 2.4 Ghz. When I got it, it did not start up. The fans would spin up and then stop. The screen doesn't even flicker. I saw that the diagnostic leds 1,2 and 3 would light up, but not the forth. So I replaced the video card and nothing changed. Next I replaced the logicboard, which then gave me a different set of leds. This time only 2 and 3 were lit. #1 and 4 never come on.

Assuming that the video card and logicboards I purchased were good, my only other option, would be the power supply or should I return these things to the store and scrap this POS?

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No, the screen never turns on. I can hear the cd drive and hard drive spin up. There is no chime. Led 2 and 3 will light up and then turn off and then on again. The fans do the same thing. And this is all prior to the drives spinning up.

The previous logicboard would have the first 3 lights lit up, but there was no chime and the screen never came on.

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Sounds like a possible bad inverter to me. Can you see the desktop at all?

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 (turn on and remain 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 (turn on and remain 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 (turn on and remain 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.

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No, the screen never turns on. I can hear the cd drive and hard drive spin up. There is no chime. Led 2 and 3 will light up and then turn off and then on again. The fans do the same thing. And this is all prior to the drives spinning up. The previous logicboard would have the first 3 lights lit up, but there was no chime and the screen never came on.

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With the lights going out, the first thing I would do is replace the power supply.

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