On my failed drive, i'm measuring continuity between all the +5 volt pins and all the ground pins on the SATA power cable connector. Also, the +5 volt TVS diode has continuity in both directions. Would the power connector shorting between +5 and ground have blown the TVS diode, or would a shorted TVS diode cause this continuity on the SATA power pins? I recently measured another hard drive with a shorted TVS diode and I did not get continuity between +5 and ground on the SATA power pins.

the tvs is in 'paralel' with the power connector, with a fuse resistor added optionally. On an overvoltage event the TVS can get shorted and the fuse blown. If it is blown, the connector pins are no longer shorted, at least if the fuse is placed correctly. Which is not true for older WD boards, where the fuse protects the TVS, so once it is blown, the overvoltage can freely pass to the main circuit and to the preamp inside the HDA.
So, answering your question, it depends on what board you have in hand.

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Adatmentés - Data recovery

An older 2TB Barracuda. Sorry for the elementary question, i'm just learning about hard drive circuit boards and have not found a comprehensive diagram of components yet, but may i ask, is the highlighted component next to the +5 TVS the fuse? Whatever it is, is also shorted.

That's a capacitor, not a fuse, and it's a Samsung drive, not a Barracuda (Seagate).

Did you do this?

Warning: do not interchange modular PSU cables:
http://www.hddoracle.com/viewtopic.php?f=56&t=2545

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A backup a day keeps DR away.

Oh sorry, correct a Samsung Barracuda Green.

Good question. I will read that article in more depth later. At first quick read i'm not sure. I didnt understand all of it. I do have a new modular PSU with an old motherboard and SATA drives, so I should definitely try to understand that article. Thank you.

I lost two Barracuda drives, one around the same time my old Enermax PSU died, but I also added a drive selector switch https://www.amazon.com/Kingwin-Optimize ... 136&sr=8-4 around the same time the PSU died. Not sure if its a coincidence or not for failure of PSU? The Enermax was maybe near a decade old

The short circuit of this drive happened some time before the PSU died, several months if i remember correctly, because I had been using it as a movie storage drive for a few years prior. with no issues with the same PSU. Its full of movies and suddenly one day the PC failed to power on. I discovered this drive was the culprit and put it in my desk thinking I would try to recover one of these days. If I remember correctly, it wasnt long afterwards that the Enermax went bad, but i think it was months afterwards but cant be exactly sure. The second Barracuda drive died right at the same time the PSU did. Shorted TVS diode and who knows what else. Luckily I had recently done a backup of that drive so didnt bother to troubleshoot it.

Oh sorry, correct a Samsung Barracuda Green.

Good question. I will read that article in more depth later. At first quick read i'm not sure. I didnt understand all of it. I do have a new modular PSU with an old motherboard and SATA drives, so I should definitely try to understand that article. Thank you.

I lost two Barracuda drives, one around the same time my old Enermax PSU died, but I also added a drive selector switch around the same time the PSU died. Not sure if its a coincidence or not for failure of PSU? The Enermax was maybe near a decade old though.

The short circuit of this drive happened some time before the PSU died, several months if i remember correctly, because I had been using it as a movie storage drive for a few years prior with no issues with the same Enermax PSU. Its full of movies and suddenly one day the PC failed to power on. I discovered this drive was the culprit and put it in my desk thinking I would try to recover one of these days. If I remember correctly, it wasnt long afterwards that the Enermax went bad, but i think it was months afterwards but cant be exactly sure. The second Barracuda drive died right at the same time the PSU did. Shorted TVS diode and who knows what else. Luckily I had recently done a backup of that drive so didnt bother to troubleshoot it.

Modular PSU cables do not have standardised pinouts. If you reused the cables from your old PSU with your new PSU, then that's what blew up all your drives.

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A backup a day keeps DR away.

Oh i see. Yeah i dont remember if I did at some point. I do have a lot of saved adaptor cables though. I will need to be very careful going forward.

I did manage to save my hard drive though, so all is well. Copying all the movies off it as we speak. Came across an older post by you on HDD Oracle website. I removed the +5 TVS diode and the short between +5 and ground disappeared, so i took a chance and plugged in the drive with an SATA/usb adaptor and it worked perfectly. Have a doner drive on the way so will just replace the diode with one from the doner drive and put it back into service.

Thanks for your help. Much appreciated.