last monday I came back from a small wekend trip, I turned my pc on from stand by and found out windows it was not working as it should so i restarted and the pc won't start.
I found out the drive is not recognized in the bios.
So i started looking on the internet and found this great website with a lot of info.
I took out my HD, a WD1001FALS-00E3A0, and attached it to a sata --> usb kit to power it on.
when I turn it on i hear 6 really soft clicks (it is coming from the pcb not the drive itself, can only hear it with my ears really close), it sounds to me like the electricty won't get through.
In the past I've also experienced another problem with another drive which had another problem, the power was still working but the drive itself was clicking, so I know the difference between clicking from the drive or from the pcb itself 
So I took out the pcb and checked the D3 and D4 with a multimeter.
D4 is dead.
I also found the U12 chip on the pcb (this is a good thing I understand from other posts?)
So I called WD and they send me a replacement drive because 'm still in the waranty period, the replacement drive is a WD1001FALS-00E8B, so this is a different pcb am I right?
Should I just remove the D4 diode and start the HD up?
Or is it better to swap the U12 from the dead pcb to the donor pcb (even while this is a different type of pcb), Anyone?
please see the attached image for detailed info