begins going bad, it can pass along power surges, spikes, and low-voltage conditions di-
rectly to the devices connected to it. The internal devices run on 12 or fewer volts of direct
current (DC) power. Any more or less than this for a prolonged period can cause a device
to degrade slowly and eventually fail.
Even when a PC is properly protected against power source issues, its environment
can cause problems. The conditions in the PC’s environment can strain its cooling system
and eventually effect the power supply. As a part of your troubleshooting processes,
check out the PC’s environment by asking these questions: Is the environment dust-free and otherwise clean? The PC is an air-cooled
device, and airborne dust and other particles are pulled into the PC’s case where
it can accumulate on the fan, air grills, motherboard components, processor, and
expansion cards. If the inside of a PC’s case is not cleaned regularly, this dust can,
at minimum, clog u pthe air flow and defeat the cooling system and directly affect
the functions of the processor, memory, and other integrated circuits on the
motherboard. Depending on the makeup of the dust, such as small metal filings
or solvent or chemical mists, it can also cause what appear to be power-related
problems by shorting the electrical distribution on the motherboard and
expansion cards.
Is the environment humid or overly dry? Too much humidity in the PC’s
environment can cause the water in the air to condense inside the PC and
cause electrical problems. On the other hand, if the air is too dry, static electricity
can be produced. It doesn’t take very much static electricity, in the form of an
electrostatic discharge (ESD), to damage the components of a PC, especially
those on circuit cards like the motherboard and expansion cards. PCs do not
need perfect operating conditions, but they do better in moderate conditions.
Regardless of whether the air is humid or dry, you should always wear an ESD
protective device, such as a wrist or heel strap, when working inside the PC.Learning from the Past
One of the most overlooked tools in the PC repair kit is a record of past problems, trouble-
shooting, installations, upgrades, and repairs that have been made on a PC, if for no other
reason than to remind you that a certain problem has happened before and what you did
to troubleshoot it. This record doesn’t need to be very formal or extensive. A small spiral
notebook with dates and a few notes on anything that has been done to the PC can be a
very valuable troubleshooting resource.
Each time you have a PC problem that requires troubleshooting, a quick review of
your PC record will remind you of past actions that could be part of the current problem.
For example, when software you use very seldom suddenly cannot read the hard disk, it
would be helpful to be reminded that a second hard disk drive was installed a month ago
as the new primary master. The solution may be to change the software’s disk drive refer-
ence rather than to replace the hard disk.Chapter 24: Troubleshooting PC Hardware^619