4-2 Assembly Access
WARNING
UNPLUG COMPUTER POWER CORD FROM AC OUTLET BEFORE
REMOVING ANY ASSEMBLY.
LETHAL
VOLTAGES ARE PRESENT INSIDE THE COMPUTER.
OBSERVE
ALL
WARNINGS IN THIS MANUAL, AND OBSERVE
THE FOLLOWING SAFETY PROCEDURES.
General Safety Procedures
The following simple precautions can save a
life.
•
00
all
possible operations with the computer unplugged from the power source.
• If installation, maintenance, or repair must
be
done with the computer energized, take the
following precautions:
a.
Never work alone
in
high-voltage areas.
In
case of accidental shock, a
life
may
depend
on
rapid removal from the energized source
and
appropriate first-aid action.
b.
Employees working
in
high-voltage areas should know where to obtain respiratory
resuscitation and/or cardiopulmonary resuscitation
(CPR), in case a fellow worker needs
assistance.
c.
In
case of burns, treat only after the person
is
breathing
and
has a normal heartbeat.
• If primary wiring change
is
made, perform continuity test between power cord ground
and
metal chassis. Record results
on
Repair Order.
CAUTION
THE COMPUTER HAS ASSEMBLIES AND COMPONENTS SENSI-
TIVE TO ELECTROSTATIC DISCHARGE. READ THE FOLLOWING
SECTION
AND OBSERVE THE PROCEDURES TO AVOID DAM-
AGE
TO THE COMPUTER AND ITS PARTS.
Electrostatic Discharge
Electrostatic discharge (ESO) causes failure in many
PC
assemblies, other assemblies,
and
compo-
nents.
Processor stack finstrates are particularly vulnerable to ESO damage. Static electricity
doesn't
appear
to
be
dangerous because much of the ESO that can cause
component
or
assembly failure
is
too small to
be
felt.
Humans
can sense a minimum ESO of 3500-5000V. However, a discharge of
300V
is
enough
to destroy
some
components.
Assemblies
and
equipment containing ESO-sensitive parts are often as sensitive as the most sensi-
tive part they contain.
Protective circuitry
in
these assemblies
and
equipment provides varying
degrees of protection from
ESO applied to their terminals. Such assemblies
and
equipment, howev-
er, are
still
vulnerable to induced ESO caused by strong electrostatic fields or by contact of electrical
connections
or
paths with a charged object.
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