Chosen Solution
Hello, After having unplugged the iMac, it won’t boot and the screen remains black (no start-up sound). The computer was in suspended mode when I disconnect the electric wire. As I replace the HardDriver (for an SSD which was amazing… till now lol) apple waranty dont works (i’ve already tried :p). After some researches i was told that it could be the logicboard and more specificly the bios battery. I replace it (not so easy :s) and now I can hear the start-up sound again… but still the screen remains black :-( As the logicboard replacement cost 1500$ i don’t know what to do… should i throw my all new iMac to the trash ? mdr Thanks for any response / lead :p
Check the diagnostic lights on the motherboard. 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.
Thanks a lot for that response ! I’ve checked the LEDs and when turned off my iMac has only LED1 ON. When turned on, it has LED1, LED2 and LED3 ON… Any additionnal clue with thoose datas ? EDIT: I’ve tried to start the machine with the flat 27" screen unplugged and… mystery the 3 led’s are still ON ! Wasn’t the 3rd led supposed to be communication with screen ? I’m confused… any clue would be very very helpfull tranks !
Whin I had this problem i ended up changing out my backlight board and that made the screen go fro pitch black nothing on to blue everything is shiney and working. Not saying that is your problem, butt you can find some on eBay for around $40.
