The “PCB” Swap Myth

Myth: I can swap the PCB from my bad hard drive with a good hard drive’s PCB and recover my data.

Knowing when a PCB is bad and when swapping it with a donor PCB could work is essential. A thorough diagnosis using high-end data recovery tools is required.

Moreover, aside from a few rare exceptions, the PCB swap myth can only work with old hard drives (circa 2000). The reason for this is the PCB’s ROM information. Embedded in a chip (or two) on the PCB is “adaptive data” unique to the hard drive it’s attached to. This “adaptive data” includes information about the hard drive’s heads, its firmware version, any bad sectors in the drive’s service area, and more. Since each PCB comes from a particular drive with different head maps, number of heads, firmware versions, and factory defects, it cannot simply be swapped and provide access to your data.

If the “bad” hard drive is completely dead, swapping the PCB may get the hard drive spinning again. However, it will likely start clicking or at least not provide access to the hard drive’s user data area. In this case, the only way to successfully perform a PCB swap is to move that unique ROM data from the original “bad” hard drive’s PCB to the donor PCB. This is accomplished using special data recovery tools or moving the ROM chip to the donor PCB.

It should also be noted that sometimes a PCB is bad, and the electronics in the hard drive fail. In that case, the PCB swap myth could destroy the donor PCB. Even more dangerous, swapping the PCB on some drives (e.g., Hitachi) could overwrite parts of the firmware in the “bad” hard drive (specifically, the NVRC module). In some cases, this could result in an unrecoverable drive.