Lesson 1: Preventive Maintenance

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Computers are, by design, very rugged and dependable pieces of equipment. However, like other machines, they age. Several basic procedures, when performed on a regular basis, can prevent premature failures. This lesson discusses how to keep computer hardware running smoothly and reliably.

After this lesson, you will be able to:

  • Extend the useful life of computer hardware.
  • Avoid major problems caused by unexpected downtime.
Estimated lesson time: 15 minutes


For the most part, computer equipment is very reliable and lasts a long time. However, as with any piece of equipment, dirt and other airborne contaminants will greatly accelerate the deterioration caused by normal use. Therefore, the best preventive maintenance is to keep the equipment clean.

The first step is to be sure that the computer is installed in a computer-friendly environment. This means that it should be in a dust-free (relatively speaking), smoke-free, and humidity-controlled (within a range of 50 to 70 percent relative humidity) location. For the most part, a normal office environment will qualify as computer-friendly. However, a normal office environment is not the only place that we find computers. Many computers are located on a warehouse floor, in a shop, or grouped together with a large industrial piece of equipment. In the event that the location of a computer is not as desirable as it should be, the frequency of preventive maintenance (cleaning) should be accelerated. In these instances, consideration should be given to establishing a computer-friendly zone around the computer, for instance, installing it into a cabinet and providing a source of clean fresh air. The following table describes what a computer technician should include in a basic cleaning kit.

Item Usage
Lint-free chamois cloth A cloth is useful for cleaning the outside surfaces.
Cleaning solution Simple soap and water should be followed by a clear water rinse. Standard household cleaning solution (not extra strength) can also be used. The solution should be applied to the lint-free cloth and then applied to the computer surface. Do not use aerosol sprays. These generally use solvents as a propellant. Solvents can damage the plastic as well as the electrical components of a computer.
Foam swabs Use these with cleaning solutions to clean small parts such as the wheels inside a mouse. (Cotton swabs are not recommended, because the cotton fibers can come off and be a contaminant themselves.)
Antistatic spray An antistatic spray or solution should follow any cleaning. A solution composed of 10 parts water to 1 part common household fabric softener will do.
Small paintbrush and/or small hand-held vacuum cleaner Used to remove dust from around the computer and inside its cabinet. The vacuum can be used to remove dust from the keyboard and other input devices.
Can of air For removing dust from the power supply fan or from inside a computer. These can be purchased from any computer supplier; they are made especially for removing dust from electronic equipment.

Never use liquids to clean inside a computer. Never apply liquids directly to the surface of a computer. Never use solvent-based cleanser or aerosols.

The proper placement or location of a computer relative to its environment is important for ease of maintenance and long life. Let's sum up good practices for placement of computer equipment. A computer should be:

  • Located in a dust-free and smoke-free environment.
  • Subjected to controlled humidity (50 to 70 percent relative humidity).
  • Subjected to controlled temperature (do not place too close to a heater or in direct sunlight—avoid temperature extremes).
  • Have good ventilation (make sure fan/ventilation vents aren't blocked).

Preventive Maintenance

For the most part, the MTBF (mean time between failures) of a computer and its peripheral devices is quite long. By following the general cleaning and safety measures just described, you can extend this time. This section describes several components and their special maintenance requirements.


Monitors require very little maintenance. To keep a monitor in peak condition:

  • Keep it clean—use periodic cleaning, dusting, and good common sense with a monitor.
  • Use simple cleaning solutions, not aerosol sprays, solvents, or commercial cleansers. DON'T use windows sprays on a monitor screen.
  • Do not leave monitors on unattended for extended periods of time. Use a screen saver or the computer's power-conservation features to prevent burn-in of the monitor screen.
  • Don't attempt to work inside the cabinet unless you are properly tranied to do so.
  • Don't tamper with the monitor. Monitors emit x-ray radiation. Changing the settings or operating the monitor with the cover removed can disable manufacturer's safety devices, thus increasing the hazard.

Hard Disk Drives

Hard disk drives are another type of device that requires very little intervention to keep running. Mechanical failure of hard drives is rare, and when it does occur the solution is generally replacement. The most common problem with hard drives is corrupted sectors. Often they can be repaired with tools such as ScanDisk (part of the Windows 95 and 98 system tools) or one of the many after-market utility software packages available. Here are a few suggestions for preventing problems with hard drives:

  • Avoid rough handling.
  • Never move a hard disk when it is still spinning.
  • Never expose the internal housing to open air.
  • Perform regular data backups.
  • Use software utilities to maintain the condition of the device (CHKDSK and ScanDisk; hard drive defragmentation programs and antivirus programs).

Floppy Disk Drives

Floppy disk drives are highly susceptible to failure. This is due mostly to the fact that they are exposed to the environment (through the disk slot) and are prone to mechanical damage from inserting and removing the disk. When they fail, the best solution is usually to replace them because they are inexpensive and simple to install. Here are a few tips to increase the life of floppy drives and disks:

  • Do not expose the disks to magnets.
  • Never touch the exposed surface of a floppy disk.
  • Do not allow smoking near a computer.

Clean the read/write heads. Special head-cleaning diskettes and solutions such as isopropyl alcohol and methanol that do not leave a residue when they dry are available. Cotton swabs are not recommended because of the fibers they shed. Use cellular foam swabs or a lint-free cloth.

Keyboards and Pointing Devices

Keeping a keyboard and mouse clean is key to prolonging their lives. Never place drinks (coffee, soda, tea, and so on) around a keyboard; spilling liquids is a common cause of keyboard failures. Here are a few tips to increase the life of a keyboard and mouse:

  • Use a hand-held vacuum cleaner to remove dust from the small crevasses.
  • Never use spray cleaners.
  • Clean a mouse or trackball by removing the ball and cleaning the x and y rollers.
  • When using a light pen, never touch the ends with your finger.


Printers are more mechanical than other peripherals and therefore require more attention. Because they use paper, ink, or carbon, printers generate pollutants that can build up and cause problems. Always check the manufacturer's recommendations for cleaning. Here are a few steps for cleaning the most popular types of printers:

Dot-Matrix Printers

  • Adjust the print-head spacing.
  • Check the tension on the print-head positioning belt. Use a non-fibrous swab dipped in alcohol to clean the print head.
  • Clean the printer's roller surfaces.
  • Clean the surface of the platen.
  • Clean the gear train of the paper-handling motor.
  • Apply light oil to the gears using a foam swab.
  • Turn the platen to distribute the oil.
  • Apply a light coating of oil to the rails.
  • Move the carriage assembly to distribute the oil.

Ink-Jet Printers

  • Adjust the print-head spacing.
  • Check the tension on the print-head-positioning belt.
  • Clean the printer and its mechanism.
  • Clean the printer's roller surfaces.
  • Clean the surface of the platen.
  • Clean the surface of the ink-jet print head.
  • Clean the gear train of the paper-handling motor.
  • Apply light oil to the gears using a foam swab.
  • Turn the platen to distribute the oil.
  • Apply a light coating of oil to the rails.
  • Move the carriage assembly to distribute the oil.

Laser Printers

  • Vacuum to remove dust buildup and excess toner from the interior. Remove the toner cartridge before vacuuming.
  • Clean the laser printer's rollers using a damp cloth or denatured alcohol.
  • Clean the gear train of the paper-handling motor using a foam swab.
  • Apply light oil to the gears using a foam swab.
  • Distribute the oil throughout the gear train.
  • Clean the writing mechanism thoroughly using compressed air. If possible, wipe the laser lens with lint-free wipes to remove fingerprints and stains.
  • Clean the corona wires using a swab dipped in alcohol. Be careful not to break any of the strands because if you do, your printer will be rendered useless until they are repaired!

Preventive Maintenance Schedule

There are no universal preventive maintenance schedules that work on every computer. Each schedule must be individualized to meet the needs of the work environment. Use the following suggestions as maintenance guidelines:

Do This Daily

  • Back up data.
  • Check computer ventilation to ensure that it is clear. Remove any paper, books, or boxes that might impede the flow of air into or out of the computer.

Do This Weekly

  • Clean the outside of the case.
  • Clean the screen.
  • Run CHKDSK or ScanDisk on all hard disk drives. Windows 95 and 98 come with scheduling programs to help you accomplish this on a regular basis.
  • Run a current antivirus program and check all drives. These programs also come with scheduling features so this can be accomplished on a regular basis. They will also remind you when to update the virus list (usually done through the manufacturer's Web site).
  • Inspect all peripheral devices.

Do This Monthly

  • Clean the inside of the system.
  • Clean the inside of any printers.
  • Vacuum the keyboard.
  • Clean the mouse ball and x and y wheels.
  • Defragment all hard disk drives.
  • Delete any unnecessary temporary files.

Do This Every Six Months

  • Perform an extensive preventive maintenance check.
  • Apply an antistatic solution to the entire computer.
  • Check and reseat all cables.
  • Run the printer's self-test programs.

Do This Annually

  • Reformat the hard disk drive and reinstall all software. Don't forget to back up data first.
  • Check all floppy disk drives.
  • Consider an upgrade to your computer. Check to see that your components can handle your workload.

Lesson Summary

The following points summarize the main elements of this lesson:

  • The best preventive maintenance is to keep a computer clean.
  • Never use solvent-based cleaners on a computer.
  • Never use liquids on the electrical components inside a computer.
  • Create and implement a regular maintenance program for each computer under your care.

Microsoft Corporation - A+ Certification Training Kit
Microsoft Corporation - A+ Certification Training Kit
Year: 2000
Pages: 127

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