IBM 6643 User Manual
Page 111
Observe
the
following
rules
when
working
on
electrical
equipment.
v
Find
the
room
emergency
power-off
(EPO)
switch,
disconnecting
switch,
or
electrical
outlet.
If
an
electrical
accident
occurs,
you
can
then
operate
the
switch
or
unplug
the
power
cord
quickly.
v
Do
not
work
alone
under
hazardous
conditions
or
near
equipment
that
has
hazardous
voltages.
v
Disconnect
all
power
before:
–
Performing
a
mechanical
inspection
–
Working
near
power
supplies
–
Removing
or
installing
main
units
v
Before
you
start
to
work
on
the
machine,
unplug
the
power
cord.
If
you
cannot
unplug
it,
ask
the
customer
to
power-off
the
wall
box
that
supplies
power
to
the
machine
and
to
lock
the
wall
box
in
the
off
position.
v
If
you
need
to
work
on
a
machine
that
has
exposed
electrical
circuits,
observe
the
following
precautions:
–
Ensure
that
another
person,
familiar
with
the
power-off
controls,
is
near
you.
Remember:
Another
person
must
be
there
to
switch
off
the
power,
if
necessary.
–
Use
only
one
hand
when
working
with
powered-on
electrical
equipment;
keep
the
other
hand
in
your
or
behind
your
back.
Remember:
There
must
be
a
complete
circuit
to
cause
electrical
shock.
By
observing
the
above
rule,
you
may
prevent
a
current
from
passing
through
your
body.
–
When
using
testers,
set
the
controls
correctly
and
use
the
approved
probe
leads
and
accessories
for
that
tester.
–
Stand
on
suitable
rubber
mats
(obtained
locally,
if
necessary)
to
insulate
you
from
grounds
such
as
metal
floor
strips
and
machine
frames.
Observe
the
special
safety
precautions
when
you
work
with
very
high
voltages;
these
instructions
are
in
the
safety
sections
of
maintenance
information.
Use
extreme
care
when
measuring
high
voltages.
v
Regularly
inspect
and
maintain
your
electrical
hand
tools
for
safe
operational
condition.
v
Do
not
use
worn
or
broken
tools
and
testers.
v
Never
assume
that
power
has
been
disconnected
from
a
circuit.
First,
check
that
it
has
been
powered-off.
v
Always
look
carefully
for
possible
hazards
in
your
work
area.
Examples
of
these
hazards
are
moist
floors,
nongrounded
power
extension
cables,
power
surges,
and
missing
safety
grounds.
v
Do
not
touch
live
electrical
circuits
with
the
reflective
surface
of
a
plastic
dental
mirror.
The
surface
is
conductive;
such
touching
can
cause
personal
injury
and
machine
damage.
v
Do
not
service
the
following
parts
(or
similar
units)
with
the
power
on
when
they
are
removed
from
their
normal
operating
places
in
a
machine.
This
practice
ensures
correct
grounding
of
the
units.)
–
Power
supply
units
–
Pumps
–
Blowers
and
fans
–
Motor
generators
v
If
an
electrical
accident
occurs:
–
Use
caution;
do
not
become
a
victim
yourself.
–
Switch
off
power.
–
Send
another
person
to
get
medical
aid.
Chapter
8.
Related
service
information
103