Motorola R-2400 Operator's Manual page 10

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Communicafions
Sector
SAFE
HANDLING
OF CMOS
INTEGRATED
CIRCT]IT DEVICES
Many of the integrated circuit
devices
used
in com-
munications equipment are
of the CMOS (Complemen-
tary Metal Oxide Semiconductor) type.
Because
of their
high open
circuit
impedance,
CMOS ICs are
vulnerable
to
damage
from
static
charges.
Care
must be taken in
handlitrg, shipping,
and
servicing
them and
the
assemblies
in which
they
are used.
Even though protection devices are provided
in
CMOS
IC inputs,
the
protection
is
effective only against
overvoltage
in the
hundreds
of
volts range such
as are
encountered
in
an
operating
system.
In
a
system,
circuit
elements
distribute static
charges
and load the CMOS
circuits,
decreasing
the
chance
of
damage. However,
CMOS circuits can
be
damaged
by improper
handling
of
the modules
even
in
a
system.
To
avoid damage
to circuits,
observe
the
following
handlitrg, shippitrg,
and servicing
precautions.
l.
Prior to and while
servicing
a circuit
module,
particularly after
moving
within the
service area,
momentarily touch both hands
to
a bare metal
earth
grounded surface. This
will
discharge
any static
charge
which may have accumulated on the person doing
the
servicing.
NOTE
Wearing Conductive
Wrist
Strap
(Motorola No. RSX40I5A) will minimize
static
buildup during
servicing.
WARNING
When wearing Conductive Wrist
Strap,
be careful near
sources
of
high
voltage.
The good ground provided by the wrist
strap
will
also
increase
the
danger
of
lethal shock from accidentially
touching
high voltage
sources.
2.
Whenever possible, avoid touching any
elec-
trically conductive parts of
the
circuit module with your
hands.
3.
Normally, circuit
modules can be inserted or
removed
with power applied
to
the unit.
However,
ChCCK
thc
INSTALLATION
ANd
MAINTENANCE
SCC-
tions
of
the manual
as
well
as
the module
schematic
diagram
to
insure there are no objections
to
this prac-
tice.
4.
When
servicing
a
circuit
module,
avoid
carpeted
areas,
dry
environments, and certain
types
of
clothing (silk, nylon, etc.)
because
they contribute to
static
buildup.
5.
All
electrically powered test equipment should
be grounded.
Apply the ground lead from the
test
equipment
to
the
circuit module before
connecting the
test
probe. Similarly, disconnect the
test
probe
prior
to
removing
the
ground
lead.
6.
If
a
circuit module
is
removed from
the system,
it
is
desirable
to lay it on
a
conductive surface (such
as a
sheet
of
aluminum
foil)
which is
connected
to ground
through l00k of
resistance.
WARNING
If
the
aluminum
foil
is connected
directly
to
ground, be cautious
of
possible
elec-
trical
shock
from contacting
the
foil
at the
same
time
as
other electrical
circuits.
7.
When soldering, be sure the soldering
iron
is
grounded.
8.
Prior
to
connecting
jumpers, replacing circuit
components,
or touching CMOS pins
(if
this
becomes
necessary
in
the
replacement
of
an integrated circuit
device),
be sure
to
discharge
any static buildup
as
described
in procedure
l.
Since
voltage differences
can
exist across
the human body,
it
is recommended
that on-
ly
one
hand
be used
if
it
is necessary
to touch pins on the
CMOS
device and associated
board
wiring.
\-
@
Motorola, Inc.
l9t2
All
Rights
Reserved
Printed in U.S.A.
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