I have a Seagate 'Barracuda 7200.10' external HDD and I grabbed the wrong power supply and turned it on. It came on for a second and went out. I looked at the thing and it said 20v 3a, and the HDD called for 12v 3a. So I think that I killed something but hopefully not the disk or the data on it. I was considering pcb replacement but was reading your forum about TVS's? What would be a good way to go here?

Measure across the TVS with an OHM meter. There should be a couple of them right around where you plug in the power on the PCB. If you have another good working board, you can test the TVS's on that so you can get a comparison. In most cases, I believe the TVS will read close to 0 ohm's when it has been blown. Then it is just a matter of swapping out the failed components, if you are comfortable doing that.

I had the exact same problem.
Remove the HDD form the casing and it started working.

Another time when i had the problem i removed the big rectangle thing closest to the DC IN
http://farm1.static.flickr.com/90/23475 ... f1e436.jpg
I just broke it off i did not solder a new one onto it., I guess it was a regulator of some sort. LOL
Someone in the forum here was very helpfull with that.

I had exactly same problem with a Barracuda 7200.10. My wife had forgot the power supply to her external USB drive, so used her laptop power supply as it fitted. Unfortunately that fed 19V and the hard drive was dead. It was her only storage place for all old photos.

Tried to put it internally in a PC, which would then not start, so I realised the hard drive had a short circuit. Measuring between ground and 12 V confirmed (no resistance, 0 ohm). 5V was ok (higher resistance).

Since I am not that literate with circuit boards I bought a replacement PCB on E-bay, but that only made the drive spin, not read/write.
I read a bit more on this forum, and realised that maybe each PCB is calibrated with unique data for the hard drive it is fitted on.

Tonight I removed the 12V TVS on the original PCB. After a couple of startups, the drive was fully back to normal! Fortunately only the TVS had been damaged, otherwise I would have required to transfer the ROM from original PCB to the replacement one.

So, I would first try with removing the TVS. Note though that this leaves the harddrive unprotected from future voltage peaks, so either scrap it or put in a new TVS!

Not each case is identical : BEWARE.

OK- so I ohm'd the TVS and found that it was indeed bad...so I pulled it off and tried it; it doesn't really have to work long term, I just want to retrieve the data. It still didn't come on. Any ideas? Does it specifically NEED the TVS? And if I went PCB replacement, could I retrieve the data on it?

Another thought, does it need to be jumped?

Removing both TVS components near the DC in made it work again. Time to make emergency copies! Thanks to all that helped! Anyone know where to get replacement components?

Replace the drive it is cheaper. Safer for your data.

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Iorana Haraharaini