Hey guys!

Like a few people here, I have made the grave mistake of plugging a 19V adapter into my external 12V HDD. I have taken it to a data recovery center for an evaluation, and the result came back with "...the hard drive was found to have electrical failure preventing normal operation of the device". They also gave me the lowest estimate for the repair ($600), which i suspect is due to the issue not being very major.

As I have read on this forum, a very common problem after such an incident is a shorted TVS diode. From reading this thread http://forum.hddguru.com/need-pcb-hitachi-1tb-hdd-hdt721010sla360-0a38016-t18870.html I have learned that on my Hitachi drive the TVS code is L14, located on the +12V rail. I have found it, and tried testing it for resistance at 200ohm. I seem to be getting a reading of 0.3, which I gather means that its not shorted. I'd really appreciate it if someone might be able to give me a hand to possibly try and identify what the problem is, and perhaps see if I may be able to fix it, or learn that it is beyond my abilities.

Also wanted to note that the device does not power up at all, and if connected to the pc via SATA prevents the PC from turning on by shutting the PSU as it is about to start.

Any advice is much appreciated!

The reading indicates that the TVS is Short.
The symptoms of the PSU not being able to power up, also indicates that the TVS is blown and shorting the power supply.

You will have to remove the TVS diode(desolder it ) and if nothing else has failed, the psu will power up and detect the drive. Use a proper power supply while testing (connect directly to the PC SATA port)

But there are chances that something else also might have failed.
Also DIY on drives with important data is not advised.

Hey sathyan, thank you very much for the response! I followed your advice, and succesfully removed the TVS diode, and it worked! Recovered about 2 weeks worth of work, which is a huge relief. Sorry for taking so long to respond, but i hugely appreciate your answer!

good job .
Replace the TVS if you plan to use the drive.
Have proper backups of your data.
Good luck