Origineel bericht door: Cees ,
Hi, When none of the LED's are lit, this means there is no power at all, and one would suspect the power supply. Don't jump to conclusions too fast, however, and check the AC input connector, mains filter and AC wiring to the PS board. If you know how to handle a multimeter, check the mains voltage on the PS board. You can also unplug the connector to the logic board, and see if you have the tricle (stand-by) voltage (about 2,5 V DC). Be aware that a power supply has protective circuits on the main output voltage line (12VDC). When there is a short circuit in the logic board (or audio board, video card etc), you won't be able to start the computer (LEDS 2/3 remain dark) but you can have the trickle voltage. I was fooled once by this situation, thinking of 'only' a defective PS, but when I pulled out the video card my iMac came back to life ! I don't know if the trickle voltage line is protected (guess not).