Recover Your Data with Hardware

Having covered the ‘deleted data' section of data recovery is all good and well, but what happens if your drive is not even being detected by your machine? Or your machine can see the drive, but just hangs when you try to access it? What about if the drive is completely dead and won't even spin up? Let's briefly cover the main components of a drive, see which components can fail, and what symptoms each failure might exhibit.
PCB: This is the (often green) circuit board attached to the bottom of your drive. It houses the main controller (the equivalent of your computer's CPU) along with many other electronic controllers. This is the interface that turns your 0s and 1s from the platter into usable data that your computer can understand.
Platters: Your drive contains one or more thin, circular platters. These spin around at anywhere between 5,900rpm to 7,200rpm on consumer drives and are the media that actually store your data. Made of glass or some form of alloy and coated with a magnetic layer, they can store anything up to 4TB of data.
Head assembly: Data from your drives' platters is read by means of a series of read and write heads. While in operation, these heads are not actually in contact with the surface of the platters. In fact, they ‘fly' nanometers above the surface of the disk, reading and writing data. Typically a drive will have 2 heads per platter, so a large capacity drive with 3 platters will be paired up with 6 heads, one for each side of each platter. If these heads fail physically or the drive is dropped or knocked over, the drive can experience a ‘head crash' where the heads no longer fly over the platters, but instead make contact with the surface and destroy your data at a few thousand revolutions per minute.
Firmware: Your drive runs its own mini operating system in order to deal with all of the data and operations required to access it. Most of this firmware is stored on the platters. A small portion is stored on the PCB, which is required when the drive starts up. Firmware can go wrong, leading to inaccessibility of your data. Unfortunately hard drive firmware is not similar to your mobile phone or tablet—you cannot just update or reflash it. Each drive has its own unique modules and parameters and is highly complex in nature.

Now that we understand the basic components of a hard drive let's look at some common failures and symptoms you might experience, determine which component could be causing the problem, and see if we can tackle some of these problems DIY style.

If Your Drive Isn't Spinning Up At All

This is the one instance where you have a relatively good chance of resurrecting your drive if you're prepared to put in some time and effort. If the drive does absolutely nothing when you apply power to it (no noises at all), it is 99% a PCB problem. With older drives, you could sometimes find a matching PCB from another matching drive, swap it over, and voila. However, on new drives, technology and architecture have changed and each drive contains microcode unique to the drive it's attached to. Simply swapping the PCB with a matching, working equivalent has almost no chance of working and can be outright dangerous to your data.
There are two main causes of failure here, either a TVS diode (fuse) has shorted due to overvoltage, or a vital component on the PCB has failed. Hard drive PCBs often have two TVS diodes which act as fuses to protect your drive in the event of a power spike. There will most likely be two of these: one for the 5v and one for the 12v rail. If you accidentally plugged in the wrong power adapter to your external drive, or you experienced a power surge, a TVS diode might have sacrificed itself. If the shorted TVS diode is the only casualty and the rest of the PCB components are OK, then simply removing the shorted diode is enough to bring the drive back to life.
You can test this with a multimeter—if the diode reads zero ohms, or close to it, then it has indeed shortened. When shorted these diodes often have a noticeable burnt smell and might have visible burn damage. Note that when a TVS diode is removed the drive is no longer protected, so ensure that the power supply you connect to the drive is correct and healthy.


If the TVS diodes don't smell burnt and show the correct digits when measuring them, then the problem is the PCB itself. A replacement PCB is required, but not just a straight swap. There is an 8 pin ROM chip on most PCBs that contains unique firmware info that is required to start up the drive. This needs to be moved from the old PCB to the new in order for the replacement to work. Some hard drives, especially Western Digitals, do not have this 8 pin chip—the firmware is stored in the main controller which is virtually impossible to move.
If you want to replace the PCB then you'll need to fine a matching replacement and have the ROM chip moved. There are many online providers that will sell you a matching PCB. Some of them even offer to move the ROM chip for you, saving you the hassle of soldering and possibly damaging the chip. If the PCB was the only damaged component and the drive's internals are OK, then after the replacement and ROM swap, your drive should be up and running again. Another PCB-related item to check are the head contacts. Sometimes they corrode with time, but are easily cleaned with a rubber eraser.