Upgrading And Repairing PCs 21st Edition: PC Diagnostics

Cleaning A System


Cigarette smoke contains chemicals that can conduct electricity and cause corrosion of computer parts. The smoke residue can infiltrate the entire system, causing corrosion and contamination of electrical contacts and sensitive components, such as optical drive lens assemblies. You should avoid smoking near computer equipment and encourage your company to develop and enforce a similar policy.

One of the most important operations in a good preventive maintenance program is regular and thorough cleaning of the system. Dust buildup on the internal components can lead to several problems. One is that the dust acts as a thermal insulator, which prevents proper system cooling. Excessive heat shortens the life of system components and adds to the thermal stress problem caused by greater temperature changes between the system’s power-on and power-off states. Additionally, the dust can contain conductive elements that can cause partial short circuits in a system. Other elements in dust and dirt can accelerate corrosion of electrical contacts, resulting in improper connections. In all, the regular removal of any layer of dust and debris from within a computer system benefits that system in the long run.

Properly cleaning the system and all the boards inside requires certain supplies and tools. In addition to the tools required to disassemble the unit, you should have these items:

  • Contact cleaning solution
  • Canned air
  • A small brush
  • Lint-free foam cleaning swabs
  • Antistatic wrist-grounding strap

You also might want to acquire these optional items:

  • Air compressor
  • Vacuum cleaner

These simple cleaning tools and chemical solutions enable you to perform most common preventive maintenance tasks.


Chemicals can be used to help clean, troubleshoot, and even repair a system. You can use several types of cleaning solutions with computers and electronic assemblies. Most fall into the following categories:

  • Standard cleaners—You can use pure isopropyl alcohol, acetone, trichloroethane, or a variety of other chemicals. Most board manufacturers and service shops are now leaning toward alcohol, acetone, or other chemicals that do not cause ozone depletion and comply with government regulations and environmental safety.

Recently, new biodegradable cleaners described as “citrus-based cleaners” have become popular in the industry, and in many cases are more effective and more economical for circuit board and contact cleaning. These cleaners are commonly known as d-limonene or citrus terpenes and are derived from orange peels, which gives them a strong (but pleasant) citric odor. Another type of terpene is called a-pinene and is derived from pine trees. You must exercise care when using these cleaners, however, because they can cause swelling of some plastics, especially silicone rubber and PVC.

CautionYou should make sure your cleaning solution is designed to clean computers or electronic assemblies. In most cases, this means that the solution should be chemically pure and free from contaminants or other unwanted substances. You should not, for example, use drugstore rubbing alcohol for cleaning electronic parts or contacts because it is not pure and could contain water or perfumes.

  • Contact cleaner/lubricants—These chemicals are similar to the standard cleaners but include a lubricating component. The lubricant eases the force required when plugging and unplugging cables and connectors, reducing strain on the devices. The lubricant coating also acts as a conductive protectant that insulates the contacts from corrosion.

A unique type of contact enhancer and lubricant called Stabilant 22 is currently on the market. This chemical greatly enhances the connection and lubricates the contact point and is much more effective than conventional contact cleaners or lubricants. It is especially effective on I/O slot connectors, adapter-card edge and pin connectors, disk drive connectors, power-supply connectors, and virtually any connector in the PC.

Note: This chemical is available in several forms. Stabilant 22 is the concentrated version, whereas Stabilant 22a is a version diluted with isopropanol in a 4:1 ratio. An even more diluted 8:1-ratio version is sold in many high-end stereo and audio shops under the name Tweek. Just 15 ml of Stabilant 22a sells for about $40; a liter of the concentrate costs about $4000! Although expensive, only a little is required in an application.

  • Dusters—Compressed gas often is used as an aid in system cleaning. You use the compressed gas as a blower to remove dust and debris from a system or component. Be careful when you use these devices because some of them can generate a static charge when the compressed gas leaves the nozzle of the can. Be sure you are using the type approved for cleaning or dusting off computer equipment, and consider wearing a static grounding strap as a precaution.

You should use compressed gas only on equipment that is powered off, to minimize any chance of damage through short circuits.

Closely related to compressed-air products are chemical-freeze sprays. These sprays are used to quickly cool down a suspected failing component, which often temporarily restores it to normal operation. These substances are not used to repair a device, but to confirm that you have found a failed device.

Note: The makeup of many of the chemicals used for cleaning electronic components has been changing because many of the chemicals originally used are now considered environmentally unsafe. You can check the safety of specific chemicals by consulting their Material Safety Data Sheets (MSDS). Most of the companies that produce chemicals used for system cleaning and maintenance have had to introduce environmentally safe replacements. The only drawback is that many of these safer chemicals cost more and usually do not work as well as those they’ve replaced.

Air Compressors and Vacuum Cleaners

Some people prefer to use an air compressor and/or a vacuum cleaner instead of canned gas dusters for cleaning a system. An air compressor or vacuum cleaner is more useful when you are cleaning a system fully loaded with dust and dirt. You can use the vacuum cleaner to suck out most of the dust and debris instead of simply blowing it around on the other components, which sometimes happens with canned air. An air compressor is normally powerful enough such that all dust and debris will be blown out of the unit, but if done indoors it can create a breathing hazard. I normally recommend using a combination of both a vacuum cleaner and an air compressor, or just an air compressor if the cleaning can be done outdoors. Some compressors and vacuum cleaners are specifically designed for use on and around electronic components; they are designed to minimize ESD while in use. If you not using one specifically designed with ESD protection, you should take precautions, such as wearing a grounding wrist strap. Also, if the device has a metal nozzle, be careful not to touch it to the circuit boards or components you are cleaning.


Use cleaning swabs to wipe off electrical contacts, connectors, and other sensitive areas. The swabs should be made of foam or synthetic chamois material that does not leave lint or dust residue. Unfortunately, proper foam or chamois cleaning swabs are more expensive than typical cotton swabs. Do not use cotton swabs because they leave cotton fibers on everything they touch. Cotton fibers are conductive in some situations and can remain on drive heads, which can scratch disks. Foam or chamois swabs can be purchased at most electronics supply stores.

CautionOne item to avoid is an eraser for cleaning contacts. Many people (including me) have recommended using a soft pencil-type eraser for cleaning circuit-board contacts. Testing has proven this to be bad advice because any such abrasive wiping on electrical contacts generates friction and a potentially damaging ESD. Also, the eraser will wear off the gold coating on many contacts, exposing the tin contact underneath, which rapidly corrodes when exposed to air.

Some companies sell premoistened contact cleaning pads soaked in a proper contact cleaner and lubricant. These pads are safe to wipe on conductors and contacts with no likelihood of ESD damage or abrasion of the gold plating.

Upgrading and Repairing PCs: 21st Edtion