iMac doesn't start up, diagnostic led #2 off
Hello, This is my problem, i have a imac 27'' EMC 2390 and it doesn't start up. I found that when AC is inserted the diagnostic led #1 is on. If i push the power button nothing, the fan doesn't start, the hdd doesn't make any noise, no boot chime and led #2 is off. I tested the power button and it works. I also tested the logic board test point, and found 12V at the pin #4 (and in fact the led #1 is on), then, if i push the power button i found 12V also at the pin #11, but the led #2 is still off.
The imac was working fine, then a night i leave it on and i found in the morning switched off.
What can i do? Can i make other test to understand where is the problem, can be the power supply or the logic board? I don't want to replace the logic board, i would try first to repair it.
Thanks to all