I would like to begin this presentation by first stating that I am not an electronic technician. Nor do I have any more than a very basic understanding of hard disk drive technology. I have a basic understanding of computer technology and of electricity. You do not have to be uber skilled to do what I did.

I successfully retrieved lost data from a dead hard disk drive for a few cents more than $100. I had been quoted $590 and up by professional data recovery firms to do what I did. The following presentation is a brief summary of what I did and how it worked. I cannot guarantee it will work for everyone. I can advise you to be very careful if you try to do any of the things that I did because it is possible that you can so badly corrupt your drive that any data on it might be lost forever.

Before you begin, do what you are doing right now. That is, go on the Internet and read, read, read and then read some more.


The disk drive was accidentally exposed to water. The water caused the printed circuit board to dysfunction. My friend, the owner of the drive replaced it and gave it to me to try to recover his data if I could. The arrangements were I could keep the drive in exchange for any data I might be able to recover from it.

My preliminary assessment was that the data was most probably intact. The platters had never been opened or exposed to air in anyway. The printed circuit board was the only part of the drive that had been damaged as a result of the accident. I wrongly assumed that I could simply, “hot swap,” the circuit board that had stopped working for another one from some other drive.

The disk drive details:

Brand: Hitachi
HDD: 5K250-250
Model: HTS542525K9SA00
RPM: 5400
Power: 5v 700mA DC
Capacity: 250GB
Type: SATA
P/N: 0A54876
MLC: DA2010

Complete 2.5″ HDD, PCB has been unscrewed

I have a source locally that is involved in dismantling and recycling computers of all kinds. He advised me that from time to time he gets small SATA drives and he has to drill a hole in them to insure that no data can ever be retrieved from any of them. However he told me that would not stop him from giving me the printed circuit boards if I wanted them.

But when I told him about my project to recover data he told me that he was uncertain why but he was pretty sure that I could not simply hot swap boards between drives with any hope of retrieving data or resurrecting a dead drive. That opinion was further substantiated by another friend who provided me with the following Internet link to the HDD Guru Forum.


The article on HDD Guru is also a basic primer that explains why it is not possible to simply hot swap one printed circuit board for another when trying to recover data. The key to understanding that is a thing called the NVRAM or the Non-Volatile Random Access Memory chip. While it would appear that two identical drives have identical circuit boards attached to them that is not totally true. It is true that the boards themselves do operate identically and removing one and replacing it with the other is a piece of cake involving a few tiny screws and some careful physical work.

PCB only, NVRAM removed and placed on top of another chip with scotch tape to avoid losing it

But the individual boards are unique in as much as all of the information about the specific hard disk drive is stored within the NVRAM chip. So while the boards will physically move from one drive to the next they will not operate unless the NVRAM chip is moved as well.

The above article includes two photos of the kind of printed circuit board I worked with including a highlighted diagram of where to find the NVRAM chip.

The first problem I addressed was moving that chip. From a casual glance at the dead drive that I had I knew that there was no way that I could ever dream of doing that type of board level electronic work. But here where I live I am familiar with a TV repair shop that has done circuit board work for me in the past when they removed and reinstalled IC circuit chips in an old Sony TV I owned.

I consulted the technician in that shop and he said that moving the NVRAM, which is basically an 8-legged EPROM or an Erasable Programmable Read Only Memory device, is an easy procedure. The NVRAM performs so that once it has been programmed the information contained in it remains non-volatile. So no matter if the power is turned on or off the data remains safe. The technician I spoke with in the TV shop advised me that he has to move those kinds of chips all of the time. It seems that in modern electronics often the new replacement part is unusable unless the original EPROM chip is removed from the old part and then soldered onto the new part. He estimated the labor cost for moving my NVRAM at $25.

The next problem I encountered was finding a donor drive. As I began this discussion I will remind you that I don’t have detailed hard disk drive knowledge. So I was kind of shooting in the dark. On the HDD GURU forums there are various discussions authored by learned individuals who speak of the various characteristics that must be matched between circuit boards. But given the gamble I was taking I determined to set my own standards as I attempted to match a donor drive to my dead drive.

I first determined that the physical description of the two drives had to match exactly (Hitachi, HDD:5K250-250, Model:HTS542525K9SA00). Next I decided that the part numbers for the printed circuit boards should also match because that would insure that the two boards would physically interchange with each other (p/n 0A54876). Finally, I decided that the MLC should also match (DA2010). I know that experienced technicians might suggest that there are other boards which would also interchange but I determined to play it safe and apply my own personal standards in selecting my donor drive.

I also note that there are other characteristics between my donor drive and my dead drive that did not match. There are a variety of numbers on both the hard disk drive enclosure as well as the two PCBs that do not match. I don’t know what those numbers mean but I assumed that if the basic information like the size of the drive, the numbers of heads, the speed, the voltage, the number of cylinders etc. all matched then the two boards would probably interchange. I also noted that if the model numbers, pin numbers, and MLC numbers matched those other characteristics should also match.

Finally, I needed a USB, SATA, hard disk drive enclosure in order to have a way to attach the repaired disk drive to my computer. There are countless numbers of them on the market and I bought mine for less than $10 from Amazon. Enough said.

When I was finally able to locate a donor drive, my cost was $55 plus freight. When it arrived the very first thing I did was record all of the characteristics about the two drives and the two PCBs so that they would not become confused during the exchange process. I then careful removed the individual PCBs using the standard static precautions employed in handling any electronic circuitry. Basically you should not touch the PCB except by the edges but there are many places on the internet that can help you understand the precautions in dealing with electrostatic discharge and how it can ruin a printed circuit board.


Bare HDD, no PCB

After I delivered the two printed circuit boards to the TV shop technician, I waited about a week to get them back. I advised the technician to retain the donor NVRAM as I supposed that if my experiment failed I could at least put it back and have one functional hard disk drive. But my concerns were unfounded. He was able to successfully exchange the NVRAM that matched my dead drive with the one that was on the donor drive PCB. When I swapped out my dead PCB with the donor PCB that now had my NVRAM chip soldered onto it, everything worked perfectly.


Just to recap exactly what I did, I had a dysfunctional hard disk drive printed circuit board which had on it the NVRAM which had all of my disk drive’s data in it. I also had a printed circuit board which was functional but which had on it an NVRAM that contained data about that other hard disk drive. I had the technician exchange the two NVRAM chips so that the functional printed circuit board now had on it my data’s NVRAM chip.

For me the work involved finding a functional drive that matched, and then carefully removing the two circuit boards and safely packing them into electrostatic bags to deliver to the TV technician.

I was able to recover all of the lost data off of my friend’s hard disk drive. The drive functions perfectly and I am actually considering installing it in my laptop as it has a greater capacity than the drive I am currently using.

The final cost for the whole operation total just a bit more than $100. The expenses were as follows:

USB SATA hard disk drive enclosure ........ $  5.58
Used Hitachi donor drive .................. $ 55.00
Shipping for above ........................ $  6.00
TV technician labor fees .................. $ 35.00

Total charges ............................. $101.58

This was a guest post by TJD.