Maintaining the System: Dell Precision WorkStation 410 Desktop Systems
Proper use of preventive maintenance procedures can keep the system in top
operating condition and minimize the need for costly, time-consuming service
procedures. This appendix contains maintenance procedures that you should
perform regularly.
Everyone inadvertently deletes files at one time or another. Also, hard-disk
drives can fail after extended use, so it is not a question of whether you
will eventually lose data, but when. To avoid such loss of data, you should
regularly make backup copies of all hard-disk drive files. Frequent, regular
backups are a must for anyone using a hard-disk drive.
The frequency with which backups should be made depends on the amount of
storage space on a hard-disk drive and the volatility of the data contained
on the drive. Heavily used systems require more frequent backups than
systems in which files are seldom changed.
Dell recommends that you back up the hard-disk drive at least once a week,
with a daily backup of those files known to have been changed. Following
these guidelines ensures the loss of no more than a day's work in the event
of a hard-disk drive failure or if you inadvertently delete one or more
important files.
As further insurance against data losses, you should keep duplicate copies of
the weekly and monthly backups at an off-site location. Doing this ensures
that you lose no more than a week's work, even if one of the on-site backups
becomes corrupted.
Tape drives are fast, convenient, and affordable devices that can back up
data at rates of up to 1.6 megabytes per second (MB/sec) (sustained, with
data compression) and can often run unattended. Dell offers tape drives with
storage capacities in the range of 200 MB to 8 gigabytes (GB) per tape
cartridge and recommends these drives and their associated backup software
for use as system backup devices.
As a last resort, you can back up a hard-disk drive's contents on diskettes,
a method that is both time-consuming and prone to human error. Also, backing
up a full 540-MB hard-disk drive requires approximately 375 diskettes (when
using 1.44-MB diskettes). Therefore, if it is absolutely necessary to use
diskettes as backup devices, any unwanted hard-disk drive files should be
deleted before a backup procedure is started.
Some hard-disk drive failures are recoverable. In these cases you may be able
to recover all lost data if the proper utility software is available. Even
losses such as accidentally deleted files or accidental reformatting of a
hard-disk drive can be reversed with these utilities.
If the computer system is running MS-DOS, many apparent data loss problems
are due to corruption or erasure of the hard-disk drive's master boot record
(MBR),
MS-DOS boot sector, or file allocation table (FAT). That is, accidental
deletion of files or accidental reformatting of the hard-disk drive alters
the MS-DOS boot sector, the FAT, and the root directory.
However, such accidents do not actually erase the contents of the hard-disk
drive files until new data is written to the sectors containing these files.
With software such as the Norton Utilities, Mace Utilities, or PC-Tools
Deluxe, the data stored in these areas can often be restored, meaning that
you can recover most, if not all, of the data.
Unlike formatting a hard-disk drive, formatting a diskette completely erases
all the data on the diskette unless you use the diskette formatting program
included in the Mace Utilities.
For a complete description of data recovery procedures and the software
needed to perform them, see The Paul Mace Guide to Data Recovery, published
by Brady.
An exhaust fan in the power supply cools the power supply and computer by
drawing air in through various openings in the computer and blowing it out
the back. However, the fan also draws dust and other particles into the
computer, causing contaminant buildup, which results in an increase in the
system's internal temperature and interferes with the operation of various
system components.
To avoid these conditions, Dell recommends keeping your work environment
clean to reduce the amount of dust and dirt around the computer, thereby
reducing the amount of contaminants drawn into the computer by the power
supply fan. In particular, you should keep the exterior of your computer and
monitor clean, and you should use a commercially available diskette-drive
head-cleaning kit to remove contaminants inside your diskette drives.
Dell recommends that you use the following tools and accessories when you
clean the computer:
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A wrist grounding strap - The proper use of a wrist grounding strap reduces
the effect of electrostatic discharge (ESD), which can damage certain
computer components. To use a wrist grounding strap, place the strap around
your wrist and attach the other end of the strap to an unpainted metal
surface in the chassis, such as the power supply bracket, that is connected
to chassis ground.
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A liquid dishwashing detergent - Use a mixture of one part liquid
dishwashing detergent and three parts water to clean the exterior of the
computer, monitor(s), and keyboard. You can also add fabric softener to
produce an antistatic solution that prevents dust from being attracted to
the monitor screen.
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A soft, lint-free cleaning cloth - Moisten the cleaning cloth with the
dishwashing detergent solution to clean the exterior of the computer system.
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A nonabrasive diskette-drive head-cleaning kit - Dell recommends that you
use a kit that contains pretreated diskettes in individually sealed packages.
These kits ensure that the cleaning solution is applied evenly over the
entire diskette-drive head surface, and they prevent contamination of the
heads by exposure to foreign substances.
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A small vacuum cleaner with a brush attachment - Use the vacuum cleaner to
remove dust and dirt from the exterior of the computer and keyboard.
A conventional monitor or keyboard cover minimizes the accumulation of dust
and other debris inside the monitor and keyboard when they are not in use.
Also, commercially available keyboard membrane covers make it possible to
use the keyboard while providing protection against foreign particles.
However, regardless of any protective covers, the monitor and keyboard must
be cleaned occasionally. To clean the exterior of the computer, monitor, and
keyboard, follow these steps:
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Turn off the computer, monitor, and any other attached peripherals, and
disconnect them from their power sources.
-
Use a vacuum cleaner to remove any dust from the slots and holes on the
computer and between the keys on the keyboard.
-
Moisten a soft cleaning cloth with a solution of three parts water and one
part liquid dishwashing detergent.
Do not soak the cloth in the solution; you must not let the solution drip
inside the computer or keyboard.
-
Use the moistened cloth to wipe the computer cover, the keyboard, and the
exterior of the monitor, including the screen.
You can clean the heads of your diskette drives by using a commercially
available diskette-drive head-cleaning kit. These kits include diskettes
pretreated with a chemical solution to nonabrasively remove contaminants
that accumulate on the drive heads during normal operation.
If the kit does not contain instructions, insert one of the pretreated
diskettes into a diskette drive and turn on the system. After 20 or 30
seconds, remove the diskette from the drive. Repeat this procedure for each
diskette drive in the computer.
 |
CAUTION:
Do not attempt to clean drive
heads with a swab. You may
accidentally misalign the heads, rendering the drive inoperable. |
This section discusses various environmental factors that can adversely
affect system performance and longevity.
Temperature extremes can cause a variety of problems, including premature
aging and failure of chips or mechanical failure of devices. Extreme
temperature fluctuations can cause chips to become loose in their sockets
and can cause expansion and contraction of disk drive platters, resulting in
read or write data errors. When you perform a low-level format operation on
a hard-disk drive, it is important to ensure that the drive's surrounding
temperature is at or near the temperature at which the drive will be
operated. Failure to do so can result in relocation of the tracks on the
disk platters.
To minimize the negative effects of temperature on system performance, follow
these guidelines:
-
Ensure that the system is operated in an environment no colder than 10°
Celsius (C) (50° Fahrenheit [F]) or hotter than 35°C (95°F).
-
Ensure that the system has adequate ventilation. Do not place it within a
closed-in wall unit or on top of cloth material, which can act as insulation.
Do not place it where it will receive direct sunlight, particularly in the
afternoon. Do not place it next to a heat source of any kind, including
heating vents during winter.
Adequate ventilation is particularly important at high altitudes. System
performance may not be optimum when the system is operating at high
temperatures as well as high altitudes.
-
Make sure that all slots and openings on the computer remain unobstructed,
especially the fan vent on the back of the computer.
-
Clean the system at regular intervals to avoid any buildup of dust and debris,
which can cause a system to overheat.
-
If the system has been exposed to abnormally cold temperatures, allow a
two-hour warm-up period to bring it up to normal operating temperature
before turning it on. Failure to do so may cause damage to internal
components, particularly the hard-disk drive.
-
If intermittent system failures are noticed, try reseating any socketed chips,
which might have become loose due to temperature fluctuations.
High-humidity conditions can cause moisture migration and penetration into
the computer. This moisture can cause corrosion of internal components and
degradation of properties such as electrical resistance, thermal
conductivity, physical strength, and size. Extreme moisture buildup inside
the computer can result in electrical shorts, which can cause serious damage
to the computer.
Each Dell system is rated to operate at 20 to 80 percent relative humidity,
with a humidity gradation of 10 percent per hour. In storage, a Dell system
can withstand from 5 to 95 percent relative humidity.
Buildings in which climate is controlled by air-conditioning in the warmer
months and by heat during the colder months usually maintain an acceptable
level of humidity for computer equipment. However, if a system is located in
an unusually humid location, a dehumidifier can be used to maintain the
humidity within an acceptable range.
Operating a system at high altitude (low pressure) reduces the efficiency of
forced and convection cooling and can result in electrical problems related
to arcing and corona effects. This condition can also cause sealed
components with internal pressure, such as electrolytic capacitors, to fail
or perform at reduced efficiency.
Each Dell system is rated to operate at altitudes from -16 to 3048 meters (m)
(-50 to 10,000 feet [ft]) and can be stored at altitudes of -16 to 10,600 m
(-50 to 35,000 ft). At 35°C (95°F), the maximum operating altitude is 914
m (3000 ft).
A clean operating environment can greatly reduce the negative effects of dust
and other particles, which act as insulators and interfere with the
operation of a system's mechanical components. Also, in addition to regular
cleaning, you should follow these guidelines to deter contamination of the
computer equipment:
- Do not permit smoking anywhere near the system.
- Do not permit food or drink near the system.
- Use dust covers when the system is not in use.
- Keep 5.25-inch diskettes in their paper sleeves, and keep all diskettes in a
closed diskette box when not in use.
- Close windows and outside doors to keep out airborne particles.
The oil from a person's fingers or prolonged exposure to high temperature or
humidity can corrode the gold-plated edge connectors and pin connectors on
various devices in the computer. This corrosion on computer connectors is a
gradual process that can eventually lead to intermittent failures of
electrical circuits.
To prevent corrosion, you should avoid touching contacts on boards and cards.
Protecting the system from corrosive elements is especially important in
moist and salty environments, which tend to promote corrosion. Also, as a
further deterrent to corrosion, the system should not be used in extreme
temperatures, as explained in "Temperature" found earlier in this
appendix.
ESD results from the buildup of static electricity on the human body and
certain other objects. This static electricity is often produced by simple
movements such as walking across a carpet. ESD is a discharge of a static
electrical charge that occurs when a person whose body contains such a
charge touches a component in the computer. This static discharge can cause
components, especially chips, to fail. ESD is a problem particularly in dry
environments where the relative humidity is below 50 percent. To reduce the
effects of ESD, you should observe the following guidelines:
-
When working inside the computer, wear a wrist grounding strap. If a wrist
grounding strap is unavailable, touch an unpainted metal surface on the
chassis periodically to neutralize any static charge.
-
If at all possible, stand on a concrete floor while working inside the
computer.
-
Use an antistatic floor mat when working inside the computer.
-
If it is necessary to work in a carpeted area, spray the carpet with an
antistatic spray and allow it to dry before beginning to work inside the
computer.
-
Keep components in their antistatic packaging until they are installed.
-
Avoid wearing clothing made of wool or synthetic materials.
Electromagnetic interference (EMI) and radio frequency interference (RFI)
from a computer can adversely affect devices such as radio and television
(TV) receivers operating near the computer. Radio frequencies emanating from
a computer system can also interfere with cordless and low-power telephones.
Conversely, RFI from high-power telephones can cause spurious characters to
appear on the system's monitor screen.
RFI is defined as any EMI with a frequency above 10 kilohertz (kHz). This
type of interference can travel from the computer to other devices through
the AC power cable and power source or through the air like transmitted
radio waves. The Federal Communications Commission (FCC) publishes specific
regulations to limit the amount of EMI and RFI emitted by computing
equipment. Each Dell system meets these FCC regulations.
To reduce the possibility of EMI and RFI, follow these guidelines:
-
Operate the system only with the computer cover installed.
-
Ensure that all expansion slots are covered either by a card-mounting bracket
or by a metal filler bracket and that all drive bays have a drive and/or a
metal insert installed. These brackets and metal inserts are available from
Dell.
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Ensure that the screws on all peripheral cable connectors are securely
fastened to their corresponding connectors on the back of the computer.
-
Always use shielded cables with metal connector shells for attaching
peripherals to the computer.
To prevent the possibility of RFI from a computer affecting TV reception,
follow these guidelines:
- Keep any TV set at least 6 ft away from the computer system.
- Use cable TV when possible.
- Use a directional outdoor TV antenna.
- Attach line filters to the TV set.
- Use 75-ohm coaxial cable for the TV set rather than twin-lead antenna wire.
- If interference occurs, rotate the computer or the TV set 90 degrees.
Because they store data magnetically, diskettes and hard-disk drives are
extremely susceptible to the effects of magnetism. Diskettes should never be
stored near magnetic sources such as the following:
- Monitors
- TV sets
- Printers
- Telephones with real bells
- Fluorescent lights
Excessive shock can damage the function, external appearance, and physical
structure of a system. Each Dell system has been designed to operate
properly after withstanding a minimum of six consecutively executed shock
pulses in the positive and negative x, y, and z axes. Each shock pulse can
measure up to 50 gravities (G) (half-sine wave) for up to 2
milliseconds (ms). In storage, the system can withstand shock pulses of 110 G
(half-sine wave) for 2 ms or 27 G (square wave) for 15 ms.
Excessive vibration can cause the same problems as mentioned earlier for
shock, as well as cause components to become loose in their sockets or
connectors. Systems can be subject to significant vibration when being
transported by vehicle or when operated in an environment with machinery
that causes vibration.
Each Dell system, when operating, is designed to withstand 0.25 G (half-sine
wave) at a sweep of 3 to 200 hertz (Hz) for 30 minutes. In storage, the
system can withstand 0.5 G at 3 to 200 Hz for 30 minutes.
Computer systems are especially sensitive to variations in voltage supplied
by the AC power source. Overvoltage, undervoltage, and transients (or spikes)
can erase data from memory or even cause components to fail. To protect
against these types of problems, power cables should always be properly
grounded and one or both of the following methods should be used:
Besides these appliances, the greatest threat to a system's supply of power
are surges or blackouts caused by electrical storms. Whenever possible, turn
off the computer and any peripherals and unplug them from their power
sources during thunderstorms.
If a blackout occurs-even a temporary one-while the system is turned on,
turn off the system immediately and disconnect it from its power source.
Leaving the system on may cause problems when the power is restored; all
other appliances left on in the area can create large voltage spikes that
can damage the system.
A number of devices are available that protect against power problems, such
as power surges, transients, and power failures. The following subsections
describe some of these devices.
Surge protectors are available in a variety of types and usually provide a
level of protection commensurate with the cost of the device. Surge
protectors prevent voltage spikes, such as those caused during an electrical
storm, from entering a system through the AC power source. Surge protectors,
however, do not offer protection against brownouts, which occur when the
voltage drops more than 20 percent below the normal AC line voltage level.
Line conditioners go beyond the overvoltage protection of surge protectors.
Line conditioners keep a computer's AC power source voltage at a fairly
constant level and, therefore, can handle brownouts. Because of this added
protection, line conditioners cost more than surge protectors-up to several
hundred dollars. However, these devices cannot protect against a complete
loss of power.
Uninterruptible power supply (UPS) systems offer the most complete protection
against variations in power because they use battery power to keep the
system running when AC power is lost. AC power, while available, charges the
battery; when AC power is lost, the battery can provide power to the system
for a limited amount of time-from 15 minutes to an hour or so-depending on
the UPS system.
UPS systems range in price from a few hundred dollars to several thousand
dollars, with the more expensive units allowing you to run larger systems
for a longer period of time when AC power is lost. UPS systems that provide
only 5 minutes of battery power let you conduct an orderly shutdown of the
system, but are not intended to provide continued operation. Surge
protectors should be used with all UPS systems, and the UPS system should be
Underwriters Laboratories (UL) safety-approved.
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