Hard drive troubleshooting

NOTE : Drive troubleshooting has the potential to destroy any data on the drive(s). Before attempting to troubleshoot hard disk drive problems, be sure to back up as much of the drive as possible. If there is no backup available, do not repartition or reformate the drive unless it is absolutely necessary and all other possible alternatives have been exhausted.

Symptom 1: The Hard drive is completely dead. If the drive does not spin up, the drive light doesn't illuminate during power-up, or you see and error message indicating that the drive is not found or not ready, follow the steps below:

• Check the power connector. Make sure the 4-pin power connector is inserted properly and completely. If the drive is being powered by a Y-connector, make sure any interim connections are secure. Use a voltmeter and measure the +5 volt (pin4) and +12-volt (pin 1) levels. If either voltage (especially the +12-volt supply) is unsually low or absent, replace the power supply.
• Check the signal connector. Make sure the drive's signal interface cable is connected securely at both the drive and the controller. If the cable is visible worn or damaged, try a new one.
• Check the CMOS Setup. Enter the CMOS setup routine and make sure that all the parameters entered for the drive are correct. Heads, cylinders, sectors per track, landing zone, and write precompensation must all be correct-otherwise, POST will not recognize the drive.
• Replace the hard drive. Try a known-good hard drive. If a known-good drive works as expected, your original drive is probably defective.
• Replace the drive controller. If problem persist with a known-good hard drive, replace the drive controller.

Hard Drives

Hard drives have quick become one of the most powerful and progressive parts of the PC. Tremendous storage capacities and outstanding speed allow unmatched performance-including use as virtual memory. However, PC also depend on the hard drive. Drive problems can prevent a system from booting, and data loss can render weeks (or months) of work inaccessible.

Hard drive interfaces
There are four major interfaces used with hard drives: ST506/412, ESDI, IDE/EIDE, and SCSI. These are older interfaces, and you will almost never encounter them unless working on an early-model i386 or older system.EIDE (Enhanced IDE) drives and interfaces appered in 1949 and have now largely replaced IDE in new systems, though the 40-pin interface is exactly the same. SCSI (Small Computer System Interface) drives are outstanding in server or multitasking systems.

Drive Troubleshooting

Computer serve little purpose without some means of long-term storage, and over the years, a large number of drives have been developed to provide access to vast amounts of information. This chapter explains the constuctuon and troubleshooting procedures for floppy disk, hard drives, CD-ROM drives, tape drives, and a series of other popular drives alternatives.

Floppy Drives
Floppy disk drives remain the standard removable-media mass-storage device. Although they are remarkably slow and offer punny-storage capacities when compared to hard drives and other mass-storage devices.

Floppy drive interface
Floppy drives use a 34-pin signal interface and a 4-pin "mate-n-lock" power connector.

Floppy disk troubleshooting
Symptom 1: The floppy drive is completely dead (the disk does not even initialize when inserted). If the drive light doesn't illuminate during power-up, or you see and error message indicating that the drive is not ready, follow the steps below:

• Check the power connector. Make sure the 4-pin power connector in inserted properly and completely. If the drive is being powered by a Y-connector, make sure any interim connections are secure. Use a voltmeter and measure the +5 volt (pin 4) and +12-volt (pin 1) levels. If either voltage (especially the +12-volt supply) is unusually low or absent, replace the power supply.
•  Check the signal connector. Make sure the 34-pin IDC header is connected securely at both the drive and the controller. If the cable is visibly worn or damage, try a new one.
• Check the CMOS setup. Enter the CMOS Setup routine and make sure that the drive is listed and selected properly. For example, if the drive is listed in CMOS as an A: drive but is physically cabled as a B: drive that controller won't recognize it. Pay particular attention to the drive type (1.44 Mbytes, 1.2 Mbytes, and so on)
• Replace the floppy drive, replace the floppy controller.
• Replace the drive controller. If problems persist with a known good floppy drive, replace the floppy controller.