Maintaining t he System D-7
To reduce the possibilit y of EMI and RFI, foll ow these guidel ines:
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.
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 attac hing peripherals
to the computer.
To prev ent th e po ss ibi li ty of RFI from a c omp ute r affecting TV rec ept ion , follow these
guidelines:
Keep any TV set at l ea st 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.
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Because they store data magnetically, diskettes and hard-dis k drives are extremely
susceptible to the effects of magnetism. Diskettes should never be stored near mag-
netic sources such as the following:
Monitors
TV sets
Printers
Telephones with real bells
Fluorescent lights
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Excessive shock can damage the function, external appearance, and p hysica l struc-
ture 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 millisecond s (ms). In storage, the syste m can withsta nd
shock pulses of 110 G (h alf-sine wave) f or 2 ms or 27 G (square wave) f or 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.
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