Wd hdd shutting down power supply

[Hudsonse]

My power supply went out and when I replaced it every time I plug in my hdd the new power supply shuts off. I assume when the first one went out it blew something on my pcb. Nothing looks burnt and I've read some posts on the tvs, I've checked the one which appears to be connected to the power it test good however another one tests bad. If I try to find a used pcb can they just be swapped or would something else need to be done, assuming the pcb was the exact model and rev?

[ShaneWard]

If the TVS diode on the hard drive is dead then all you need to do is snip it off and replace the component with another one from a another drive. the PCB of that hard drive should be okay, but it will need a new DIODE for protection.

[Hudsonse]

Here is the photo the one on lower right seems to test good upper right tests bad

Attachments

[Hudsonse]

Sorry photo rotated left one buy connector tests ok right one test bad

[ShaneWard]

But remember that once you do your hard drive will be unprotected so if you get a power failure again your hard drive will die! Its good to replace the old DIODE with another one from a old hard drive you no longer need ASAP.

Shane

[fzabkar]

@Hudsonse, if D3 is shorted, then I would be very wary of your new PSU, especially if it uses modular cables. The pinouts for these cable are not standardised, so if you use the cables from your old PSU with your new one, then there is a very real chance that you will impress 12V on the 5V supply, in which case you will kill the drive's preamp. I have also seen cases, in this forum, where the 5V supply is reverse polarised.

[Hudsonse]

what fzabkar said is exactly what I think happened, once I cut the d3 and plugged in the drive with the new psu but the old cables the pcb smoked the flat square ic labeled u11 in the top right corner of the board from the photo. Thanks for the information fzabkar, I just wish I would of been a little more patient in making the repair.

[fzabkar]

@Spildit, I wouldn't beat yourself up about it. I think Hudsonse would be the first to admit that the reason for the damage should have been more closely investigated. There are plenty of warnings to that effect in just about every TVS diode thread.

BTW, I'm surprised that R67 survived the original overvoltage. In desktop applications it usually (?) goes open circuit and the motor controller and preamp are then clobbered.