(Appox. 846 words)

Cleaning Inside your PC
Written by Gary Bentley, Editor, SouthWest International Personal Computer Club (TX) Throughput, February 2009
www.swipcc.org
bentley.gary (at) gmail.com

This article has been obtained from APCUG with the author’s permission for publication by APCUG member groups; all other uses require the permission of the author (see e-mail address above).

When I worked for GTE Lenkurt (subsequently GTE Network Systems) in El Paso 1978 – 1982 as a technologist and supervisor of electrical performance quality assurance for their telecommunications equipment produced at that location we were required to be very cognizant of the risk of damage to integrated circuits posed by static electricity.
Even static charges that produce no visible spark are sufficient to destroy, or worse, cause subsequent intermittent failure of high impedance inputs on many PC’s (non catastrophic damage is more pernicious because it may permit equipment to pass performance testing and fail later in the field, also, intermittent hardware failures are difficult to troubleshoot because you have to be observing the device while it is in failure
mode). 

All personnel were required to wear grounded wrist straps and work on grounded conducting pads when handling integrated circuit boards. Unfortunately, the plastic tip of a household or automobile portable vacuum cleaner does not conduct electricity and so can build up a significant static electric charge when there are large volumes of air-borne dust particles swirling within and without the plastic vacuum cleaner nozzle (think of rubbing a balloon on your head and recall the immediate build up of electric charge).
There are various brands of canned dust removing gas with a form of difluoroethane gas that is static free. Combining blowing the dust away with that gas and using a cloth dampened with a dust remover will assure that you do not subject the integrated circuits of your computer to static electricity. Make sure to wipe or blow clean the openings 
in the case for cooling fans (to assure your system does not overheat). Do not blow the dust remover into a fan in such a way as to spin the fan, or else hold the fan while you spray it as you may create an induced electrical current back into the motherboard (remember that a motor can be a generator).

You may get away with using a vacuum cleaner some of the time, or may think you have until you observe strange intermittent failures down the road (strange crashes, blue screen of death, corrupt files or boot failures). Such failures would require you to replace CPU, memory, motherboard, video graphics card, or power supply (and the failure of any of these components may have corrupted the hard drive and all your
data) or simply junk the PC (since the cost of replacement and repair may equal the cost of a new PC tower). 

If you unplug the computer prior to cleaning it, remember that the computer will no longer be grounded. So, if you are wearing a grounded wrist strap you should keep one hand on a metal portion of the PC case to maintain a ground path for static charges (or ground the case with a clip to your ground pad). Note of warning: If you still have an
old CRT monitor, stay out of that monitor case as there are lethal voltages that remain in the CRT even when it is unplugged, a CRT being rather like a huge capacitor (unless you have been trained how to drain the CRT without electrocuting yourself).

If you must use a vacuum cleaner on your PC, use one specially designed for cleaning electronic devices containing static sensitive components. If folks tell you that standard vacuum cleaners, even small hand held devices, pose no actual danger to your PC, ask yourself why 3M Company, for example, sells a Service Vacuum (3M Service Vacuum and 3M Vacuum in a Tool Case) that keeps the motor portion (with high electromagnetic
fields that could damage data on a hard drive) in the carrying case and permits the service technician to vacuum the inside of the PC or other electronic device with a long hose with static dissipative attachments (dusting brush, crevice nozzle, needle nose
nozzle) “to prevent static buildup” for use “involving static sensitive electronic components such as circuit boards” (quoted from 3M Service Vacuum and Vacuum in a Tool Case Operating Instruction manual).

Paraphrasing Clint Eastwood in Dirty Harry, if you intend to use your home
vacuum cleaner (portable or otherwise) inside your PC case you gotta ask yourself,
“Do you feel lucky, well, do ‘’ya?”

Mr. Bentley studied electrical engineering
at the University of Texas, began
working in the electronics industry in
1978 with GTE Network Systems
(Lenkurt), then software engineering
with various startups in the 1980’s, designing
and implementing, among other
things, pre-Internet email communications
systems multitasking on Intel platforms
and MSDOS PC’s. 1984 - 1986.
Gary now provides Information Technology
consulting services in the El Paso,
Texas and Las Cruces, New Mexico areas.
Gary has edited and contributed
articles to the award-winning Southwest
International Personal Computer Club
monthly magazine, “Throughput”, since
December, 2003.