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1.6, 1.8, or 2 GHz G5 processor

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Has power but will not boot, whats wrong?

I have a 1st generation Imac G5 with a 17" screen. It has power, light comes on in front and fans spin like crazy but nothing else happens. No start up noise no picture, just a black screen. Tried some basic things but would like more input. Some capacitors are junk... could this be it?

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If it has the bad capacitors it may be gone although there are now places on the web specializing in this repair for under $100. Look at the LED diagnostic lights in the middle of the logic board to locate the failure.


LED 1 indicates that trickle voltage from the power supply has been detected. This LED will be ON when the computer is turned off and your power supply is working correctly.

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.

LED 4 lights only if the computer detects an over-temperature condition. This LED will be OFF when the computer is turned on and running at the correct temperature.

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thanks, the first one is lit up, (i think that just means it has power?) then the second one will come on when i try to start it up. at one point number 4 came on red, any idea what that means? thanks for your help


alright, i have yet to see the third one turn on. Is there any possibility other than bad capacitors?


This machine also had a problem with the solder joint on the GPU (video card). This is documented on the web along with people specializing with this repair.


ok, so do you know how i would check that?


Hook it up to an external monitor. If the problem remains, then it'd the GPU.


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