How to diagnose if iMac won't boot up
Hi,
My IMAC won't boot up. Nothing happens when I click the turn on button.
I've viewed some similar questions, I still don't know where the diagnostic LEDs are.
It seems nothing is on on the logic board.
I'll appreciate if someone and point where the LEDs are in a image.
Or send me a Technician Guide.
Or advice how to test my PSU
Thanks very much!
------------------------------updated--------------------------
I guess I found where are the LEDs
So it seems none of them are lit.
From Apple service manual, it says if LED#1 is not lit, I need to replace the PSU
But I really doubt it because I check my pinout of the PSU:
From up to down is:
3.3V
0V
0V
0V
0V
0V
0V(gnd)
0V(gnd)
0V(gnd)
12V
12V
12V
I think at least the standby power is correct, because it writes on the front side of the PSU
And when I click the start button the 3.3V will be pulled down to 0V
So can I confirm that it is the logic board issue and I need to replace it?
Thanks!
Is this a good question?