I managed to connect 19V power to a QNAP NAS expecting 12, and blew the NAS and 4 of these WD drives. I've been doing some research, and it appears there's a possibility I can get the drives to spin up again by snipping a TVS diode. Unfortunately, there's no labels on the PCB, so I've attached an image here hoping someone can confirm my guesses or tell me I'm way off

I've marked what I believe are the diodes:

1) This appears to not be connected - Out of range with ohm meter at 20M
2) 0-0.1 Ohm, both directions
3) 0-0.1 Ohm, both directions

Should I, in theory, get the drive to spin up by snipping 2 and 3?

Nope, the TVS diodes on this one are the two much larger black components just up from the two you marked. Check those and see if they read near 0 ohms in both directions.

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Data Medics - Hard Drive, SSD, and RAID Data Recovery Service Company

Here I circled them for you:

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Data Medics - Hard Drive, SSD, and RAID Data Recovery Service Company

Thanks!

The leftmost of the two you circled shows close to 0 ohm, both directions. The rightmost shows 2.4 kOhm and 600 Ohm, and the diode tester doesn't complain about it.

So, in theory I could snip the leftmost diode and get the drive spinning enough to get data off, as long as I don't mess up the voltage again?

Component #1 is a zero-ohm resistor (or fuse?). The 12V TVS diode (Z4) will be shorted (as you have already determined). You can snip the diode, but you will need to replace the "fuse". You can use a blob of solder or a wire link as long as there is no other damage to the PCB.

BTW, you say that you "blew the NAS" and the drives. If the NAS really is damaged, could you upload detailed photos of both sides of its PCB? Perhaps there is a simple DIY solution.

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A backup a day keeps DR away.

Thanks! All drives are spinning and 14TB of data's being copied off.

The NAS that died is a QNAP TS-451A. Attached photos of the main PCB. If you have suggestions for testing and DIY fixing I'd love to try fiddling with it.

Could you provide close-up shots of these areas?

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A backup a day keeps DR away.

Here's the images, are they usable?

Can you measure the voltages on these pins?

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A backup a day keeps DR away.