Yesterday I hooked up my 5V molex power rail to the 12V power rail in my PSU (it’s modular) and cooked both of my hard drives. They do not spin up at all and are not recognized by the mobo, so I am hoping it is just a problem with the board.
Here is the picture of the board from my WD1500ADFD:
I had tested the D3 diode with my multimeter and found a 0V drop in both directions, so I figured it was a TVS diode and cut it off the board. Turns out the board was shorting the diode, because I measured it after lifting one side off and the voltage drop was back.
Can anyone help me with what I should try next? I am willing to get a spare logic board and transplant U12 if necessary.