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Maintenance
1.1
Battery
replacement
When
Hoe power
to
the
Model
707
A
is
turned
off,
the lithium
battery
on
the
digital
board provides
backup power
to
the
memory
in
which
setups
and
parameters
are stored.
The
bat-
tery
has
enough
capacity
to
maintain data
for
one
year of
continuous
power
off,
or
two
years
if
the
Model 707A
is
powered on
for
12 hours every
day.
The
battery
by
itself
has
a shelf
life
of
eight years.
Although
the
Model
707
A
will
op-
erate
without
a
battery,
it
will
not retain
any
setups or
param-
eters
when
turned
off
and
will
power
up
in
random
conditions.
The
battery
may
be
replaced with
any
CR2450
lithium coin
cell.
It
can
also
be ordered
from
Keithley Instruments
(part
number
BA-44),
as
discussed
in
Section 8 of
this
manual.
Replacement
of
the lithium battery
is
normally
a
safe
proce-
dure
as long
as
these safety precautions are followed.
WARNING
The
precautions
below
must
be followed
to
avoid
possible
personal
injury.
1.
Wear
safety glasses
or
goggles
when
working
with
lith-
ium
batteries.
2.
Do
not
short the battery
terminals
together.
3.
Do
not
incinerate
or otherwise
expose
to
excessive heat
(>6()T).
4.
Keep
lithium
batteries
away
from
all
liquids.
5.
Do
not recharge lithium
batteries.
6.
Observe
proper
polarity
when
inserting battery into
holder.
Replace
the battery as follows:
1
.
Turn
off the
power
and
remove
the
line
cord from
the
Model
707A.
2.
Remove
the
left
handle and
side panel.
(See paragraph
7.5.)
3.
The
lithium battery
is
on
the digital
board.
Pry
the bat-
tery
out of
its
holder using
a
non-metallic
tool.
WARNING
Do
not
use a metal
tool to
pry out
the
batteiy as
you
could short
its
terminals.
4.
Install
the
new
battery,
taking care to
observe proper
polarity as
stamped on
the battery holder.
5.
Reinstall the
left
side
panel
and
handle.
6.
Reinstall the
power
line
cord
and
turn
on
the
Model
707A.
It
will
power up
in
random
conditions,
such
as
make/break and break/make on
the
same
rows.
7.8
Static-sensitive
devices
CMOS
devices
are
designed
to
operate
at
high
impedance
levels for
lower
power
consumption.
As
a
result,
any
static
charge
that
builds
up on your person
or clothing
may
be
suf-
ficient to
destroy
these devices
if
they are not
handled prop-
erly.
Use
the
precautions
below
when
handling
static-
sensitive
devices:
NOTE
Since
the
many
CMOS
devices
installed in
the
Model
707
A
are
not
denoted
in this
manual,
all
ICs and
transistors
should
be
handled
as
static-sensitive
devices.
1.
Transport such devices only
in
containers
designed
to
prevent
static
build-up. Typically, these parts will
be
received
in anti-static
containers
of
plastic
or
foam.
Always
leave
the devices
in
question
in their
original
containers
until
ready
for
installation.
2.
Remove
the devices
from
their
protective
containers
only
at
a properly
grounded
work
station.
Also ground
yourself with a
suitable wrist
strap.
3.
Handle
the devices only
by
the
body;
do
not
touch
the
pins or terminals.
4.
Any
printed
circuit
board
into
which
the
device
is
to
be
inserted
must
also
be
properly
grounded
to
the
bench
or
table.
5.
Use
only
anti-static
type de-soldering
tools.
6.
Use
only
soldering
irons
with properly
grounded
tips.
7.
Once
the
device
is
installed
on
the
PC
board,
it
is
usually
adequately
protected,
and normal
handling
can resume.
7.9
Mainframe
troubleshooting
This troubleshooting
information
is
intended
for qualified
personnel
having
a
basic
understanding of
digital
and analog
circuitry.
The
individual
should
also
be experienced
at
using
common
test
equipment,
as
well
as
ordinary troubleshooting
procedures.
The
information has
been
written
to
assist in iso-
lating
a defective
circuit
or
circuit section.
Isolation
of
the
specific
component
is
left
to
the technician.
7-9
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