Troubleshooting and Repairing Hard Disk

If a hard drive has a mechanical problem inside the sealed head disk assembly (HDA), repairing the drive is usually unfeasible. It might be doable, but purchasing a new drive will be far less expensive. If the failure is in the logic board, that board can be replaced with one from a donor drive.

Typically, this is done only for the purposes of reading the information on the failed drive because you must purchase a complete second drive to cannibalize for the logic board. The drive manufacturers usually don't sell spare parts for their drives anymore.

Most hard disk drive problems are not mechanical hardware problems; instead, they are "soft" problems that can be solved by a new LLF and defect-mapping session. Soft problems are characterized by a drive that sounds normal but produces various read and write errors.

Hard problems are mechanical, such as when the drive sounds as though it contains loose marbles. Constant scraping and grinding noises from the drive, with no reading or writing capability, also qualify as hard errors. In these cases, an LLF is unlikely to put the drive back into service.

If a hardware problem is indicated, first replace the logic-board assembly. You can make this repair yourself and, if successful, you can recover the data from the drive. If replacing the logic assembly does not solve the problem, contact the manufacturer or a specialized repair shop that has clean-room facilities for hard disk repair.

See the Vendor's List on the DVD for a list of drive manufacturers and companies that specialize in hard disk drive repair. However, because of the costs, simply purchasing a new drive is probably more economical.

Testing a Drive

When accessing a drive, determining whether the drive has been partitioned and formatted properly is easy. A simple test can tell you whether a stored drive is in its "raw" condition or has been partitioned and formatted properly. These tests work best if you have a boot disk available and if the spare hard drive is the only hard drive attached.

First, attach the drive to your system. If you can attach power and data cables to it, you need not install it into a drive bay unless you are planning to use it immediately. If the drive will be run loose, I recommend placing it on a nonconductive foam pad or other soft surface.

This insulates the drive from potential shocks and other hazards. After detecting the drive in the BIOS and saving the changes, start your operating system from the boot disk. Then, from the A: prompt, enter the following command:


This produces one of the following responses:

  • Invalid drive specification. This indicates the drive does not have a valid partition (created by FDISK) or that the existing Master Boot Sector or partition tables have been damaged. No matter what, the drive must be partitioned and FORMATted before use.

You also get this warning on a FAT32 or NTFS partitioned drive if you use a Windows 95 (original version) or MS-DOS boot disk when checking. Use a Windows 95B, Windows 98/Me, or Windows 2000 boot disk to avoid this false message from FAT32 partitions. Or, use a Windows NT, Windows 2000, or Windows XP boot disk to detect NTFS partitions.

  • Invalid media type. This drive has been partitioned but not FORMATted, or the format has been corrupted. You should use FDISK's #4 option to examine the drive's existing partitions and either delete them and create new ones or keep the existing partitions and run FORMAT on each drive letter.

  • Directory of C: . The contents of the C: drive are listed, indicating the drive was stored with a valid FDISK and FORMAT structure and data.