What the heck is wrong with my hard drive?

brendanz77

Reputable
Mar 23, 2014
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Hey guys! I want to go ahead and thank you before for reading my post and giving it any thought. Any helpful comments are appreciated, so without further ado:

A few years ago I shorted out my external Hitachi hard drive by giving it too much power, 15V as opposed to the 9V-12V that is requires (I forget which). After this incident, the drive would not power up and was kept in a dark closet for the next 2 or 3 years. A couple of weeks ago I decided to take it apart (more as a learning experiment) and got it into my head that I could replace the PCB, which seemed to have suffered short circuiting damage, and make the drive work again.

I ordered an exact copy of the PCB and did some research as to the procedures of transferring the PCBs (at this point the hard drive was out of its enclosure and stripped of its SATA to USB converter; consider it a bare 2.5" drive). I came across something saying that in most cases the ROM (the chip on the PCB containing drive specific information) chip has to be transferred from one PCB to another for the transfer to take effect--usually because there are different firmware builds from one batch of PCBs to another, even though the PCBs might physically be the same.

I transferred the ROM chip from the shorted PCB to the new one and made sure its orientation was correct (all done with a hot-air station). During the transfer I blew off one of the minutely small chips next to the ROM chip (a little smaller than a grain of table salt) and soldered it back on quite messily (I might have done the re-soldering of this piece wrong since it was so flipping small). I plugged the drive in and listened as it spun up (confirmed by feeling the soft vibration of the drive). The computer did not recognize it.

My next attempt at fixing the drive was to take a PCB off of an identical drive since I had ordered two at once. I didn't bother transferring the ROM chip between the two drives as I assumed that they were probably made in the same batch. Doing this resulted in the drive powering up, but not being able to be recognized by the computer.

It seems to me that something other than the PCB was broken or damaged as a result of the shorted circuit, but I don't know where to go from here. If I could get the hard drive to be recognized by the computer, then I'd be able to run a diagnostic on it. What next?