Dell OptiPlex NX1, User Manual

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Maintaining the System 2-5
To reduce the possibility of EMI and RFI as well as to prevent RFI from a computer
affecting television reception, follow these guidelines:
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Operate the system only with the computer cover installed.
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Ensure that all expansion slots are covered by a card-mounting bracket or a metal
filler bracket.
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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.
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Always use shielded cables with metal connector shells for attaching peripherals
to the computer.
To prevent the possibility of RFI from a computer affecting television reception, follow
these guidelines:
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Keep any television at least 6 ft away from the computer system.
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Use cable television when possible.
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Use a directional outdoor television antenna.
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Attach line filters to the television.
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Use 75-ohm coaxial cable for the television rather than twin-lead antenna wire.
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If interference occurs, rotate the computer or the television 90 degrees.
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Because they store data magnetically, hard-disk drives are extremely susceptible to
the effects of magnetism.
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Audio speakers can be a source of magnetic energy if they are not properly shielded.
Speakers used in music systems are typically enclosed in wooden cabinets, which
provide no magnetic shielding. Multimedia speakers for computer systems are mag-
netically shielded inside a metallic case and are thus the only type of speakers
recommended for use with multimedia computer systems.
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Excessive shock can damage the function, external appearance, and physical struc-
ture of a system. Excessive vibration can cause the same problems as excessive
shock does and can cause components to become loose in their sockets or connec-
tors. Systems can be subjected 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 a left side (for vertical ori-
entation using the optional stand) and bottom half-sine pulse with a change in velocity
of 50.8 centimeters per second (cm/sec) (20 inches/sec). In storage, the system can
withstand a 26,478-cm/sec
2
(27-gravities) faired square wave with a velocity change
of 508 cm/sec (200 inches/sec).