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PCB Swapping

June 23, 2014

What a Hard Drive Printed Circuit Board Is (and What It Does)

A hard drive’s Printed Circuit Board, or PCB, allows electricity to pass between various components that allow the hard drive to function. If you have ever handled a hard drive, you may recognize the PCB as the green or blue board on the bottom of the device.

There are various chips on the PCB, including one that contains firmware with a number of drive-specific attributes such as voice coil voltage, spindle speed, head-to-head relation (HHR) and various other information. This information is critical for the drive’s operation.

In extremely simplified terms, the board “tells” the hard drive how to operate. It processes signals from the computer and allows the drive to output information to the central processing unit (CPU). However, it is not the primary storage space for user data, and it does not have any mechanical components.

Fried PCB

Common Issues That Affect a Hard Drive’s Printed Circuit Board

A hard drive PCB is fairly resilient, but it can become damaged during normal operation. Some common causes of hard drive circuit board failure are listed below, along with tips for preventing premature damage.

  • Extreme Heat – The inside of a computer can get extremely hot, especially if the user doesn’t take precautions to provide adequate ventilation. Heat can eventually cause electronic malfunctions.
  • Damage from Improper Handling – Electrostatic discharge can permanently damage electronic components. Always ground yourself before handling your hard drive.
  • Damage from Faulty Electrical Supply – A computer power supply may send inconsistent levels of electricity through the motherboard and to components, resulting in damage. High-quality power supplies are well worth the investment.
  • Damage from Power Surges – We recommend keeping every computer on an uninterruptible power supply (UPS) to keep power surges from damaging hard drive circuit boards. Power surges can also affect other computer components, so a UPS is an essential means of protection.
  • Manufacturing Issues – While rare, some circuit boards have manufacturing issues that cause components to become unseated. This can occur even when the hard drive is operating in a reasonably well-controlled environment.

Failure Symptoms That Accompany PCB Issues

A printed circuit board failure will often cause a hard drive to stop functioning entirely. However, this is not always the case. The drive may appear to start normally; you may hear the platters spinning up to speed, and the drive might not make any unusual sounds.

If your hard drive is a boot drive, it may not be able to load your operating system. If it is not a boot drive, you may not be able to access any files or folders. You may hear clicking or whirring sounds.

The symptoms of PCB failure are not consistent, and there’s a tremendous amount of overlap with other issues such as read/write head failures. Because of this, you should never operate a hard drive that shows any signs of damage, especially if you don’t have a backup of your data. Instead, call us at 1.800.237.4200 to discuss hard drive data recovery options.

Can I Switch Out My Hard Drive’s Printed Circuit Board?

There is an extremely common misconception that hard drive PCBs are interchangeable among certain models (for instance, that Hitachi Travelstar drives have identical circuit boards). While this was true for early hard drives, all modern disks use drive-specific microcode. This allows for excellent dependability, fast read/write speeds, and generally better performance for high-capacity hard drives.

However, it prevents end users from switching out failed circuit boards. Even if you attempted to transplant your hard drive’s original firmware chip onto a new, identical board, you could cause problems that would permanently destroy your files.’s engineers can copy, rewrite, or repair microcode using advanced equipment. We take extensive precautions to protect your disk at all times, and all of our laboratories have microcode repair tools – we don’t automatically outsource electronically damaged drives to a central location, and our process gives you the highest possible chances of a fast, successful recovery. We recover over 97 percent of hard drives with PCB damage (hard drive data recovery service).

To learn more or to start a case, call 1.800.237.4200 today.

Hard drive printed circuit board, electronics, controller chipHard drive PCB back with traces, contacts, solder points