One of the common problems you will find when entering into the field of data recovery is that clean room work is only a small scope of the work you do. The rest can range from simple logical recovery, ATA password removal, firmware corruption, and PCB failures. Today I’m going to inform you a little about the latter.
Let me first say that if you are not familiar with the workings of a hard drive, or a computer for that matter; I do not recommend performing these procedures yourself. Even attempting something such as a PCB swap can put your valuable data at risk.
Before you completely swap a PCB, you must determine whether or not the PCB is the cause of the problem. To do this we must diagnose! If you have professional HD diagnostic tools on hand; this makes the job much easier. We are going to pretend we don’t; because not everyone can afford these tools as they can come at a steep price.
First, you are going to want the drive able to be powered on and in a place you can reach it. Once you have done this; power on the drive put your ear to it. For beginners, it may be hard to determine if the drive is making abnormal sounds. If the drive is making a repetitive clicking noise; this is most likely a problem more advanced then a PCB failure; and we will cover this another time.
If the clicking is present there is still a very small chance it may be the drive’s PCB; but let’s assume the drive had no clicking and continue.
Another scenario is that the drive does not power on at all; this is actually one of the most common signs of PCB failure. If your drive in question does not power on whatsoever; the following course of action needs to be taken:
First, you must obtain an identical drive, or as close as you can. Finding an identical match is different for every drive manufacturer, and model. Usually, you would want to match things like: model number, P/N (product number), Firmware revision, country of manufacturer, and site code. The site code can be difficult to locate, and understand, but with a little time and Google; you can find your answer.
Once you have located a match; it’s time to go to work. The first thing you will want to do is remove the PCB from the “bad drive” and put the suspected bad board on to your new “good drive” and observe if the same symptoms occur. If the drive seemingly starts up fine; the PCB may not be the problem and further diagnosis is required (which we will cover another time). If the drive exhibits the same behavior as the “bad drive” then it’s almost a sure shot that the PCB is the culprit.
Now we know that the PCB has failed. Most of the time, it has something to do with the fuses or some part of the power system of the chip. Sometimes, if you identify that the problem is a bad fuse you may bypass the fuse with a small piece of wire (electrically conductive). I don’t typically recommend this unless you absolutely cannot find a donor PCB; just because the fuse is what protects the important chips from damage. This brings us to the chip/chips that we DO need.
There are many scenarios of chips depending again on manufacturer, model, and the year that the drive was manufactured. The first chip is the EEPROM (Electrically erasable programmable read-only memory) which; besides being a mouthful to say, is essentially a form of flash memory that acts as the HDD’s BIOS it can contain important calibration data that is specific to that exact drive. Without going in to too much detail; every single hard drive is different, whether it be slightly misaligned, or had a couple bad sectors from the factory; the drive takes this into consideration and makes adjustments and saves them into this memory. This is why a board swap without swapping this chip typically does not work.
Another chip that may appear is the NVRAM (Non-Volatile random access memory). This is typically found on Hitachi drives; and contains extra data similar to the Calibration data found on the EEPROM. If you have to swap chips from Hitachi drives; the EEPROM and NVRAM will need to be swapped. Some drives may seem like they do not have an EEPROM; this usually means that the EEPROM is embedded within the CPU of the PCB; in this case you will just swap the CPU.
Swapping the chips may require slightly modified methods depending on the “form factor” of the drive. Some PCB may have “BGA” (Ball grid array) chip. This means that the solder is under the chip; and while you can remove these chips fairly easily, putting them back on requires a special “infrared” rework station. Expect to see BGA chips on smaller drives; 1inch and 1.8inch drives.
Assuming that the chips are not BGA chips, you will want to obtain a Heat gun capable of outputting ~260c (500f). You may want to pick up a variety of tips; particularly finer point tips so that you can be more precise where you are directing the heat. You will also want a good pair of tweezers for grabbing the chips you need to get off; as using your fingers would be a bad idea on many levels. Before you begin heating the chip be aware of surrounding objects such as capacitors and any other pieces of the chip that are soldered onto the board and will be under the scope of the heat gun; as they will be movable once heated and you must avoid them. Also make sure that the heat gun is not hitting the plastic where the interface connector is. It will in fact, melt. You must grab the chip while the gun is still running, because solder solidifies quickly and you will not have enough time to remove it if you simply heat it up and then attempt to grab it right after you turn the heat off.
Like this
or this
OK, so you have gotten all the chips needed off of the bad board; and prepared the good board by removing its chips. Now we must solder the EEPROM and any other chips needed on to the good board. For the best results you are going to want a soldering station that can output ~320c (603f). This will allow for the smoothest solder. As far as the tip of the soldering iron goes; find one that works best for you. Remember, you are working with very small chips so you need maximum precision; you don’t want to accidentally cook the top of the chip because you slipped. You will also need some sort of FLUX (used to remove oxidation) typically a Rosin flux pen will work just fine; just make sure it is not activated, because this can cause major damage to the board. Rosin-core Solder will be sufficient, or any solder labeled “for PC work”
example (not actually soldering here, just showing placement)
You won’t become a professional solderer overnight. If you have some old PCB you can practice on I would highly recommend this.
So that’s basically it. You removed the EEPROM and any other valuable chips off of the “bad pcb” and then soldered them onto the “good pcb”. Now all you have to do is install the soldered good pcb onto the “bad drive” and plug it in! If the pcb was the culprit; you will now be able to access your data. Keep in mind this is for data recovery purposes. I do not recommend using this technique as a “repair”. While the drive may seem rock solid; and it may be, it may also be very unstable and die at any time. I only recommend this technique for getting it up and running to extract the data to a safe source.
-HDD Doctor
