either cabinet
half
as
it
is liften
off,
it
can drop
free
and
be
damaged.
2.
Remove
the
bottom
cabinet
half
and
note
the
position
and
routing
of
the
power
cord
and
probe
lead (see
Figure
4-4)
and
the
PWR
(BTRY)
LED led (see Figure 4-9). Lift
the
instrument
out
of
the
top
cabinet
half
and
set
the
cabi-
net
halves aside.
Be
sure
the
rear panel
insulated
compart-
ment
cover
and
the
cabinet
screws
have
not
fallen free
to
become
I
ost.
CABINET
REPLACEMENT. Replace
the
cabinet
halves
in
tlie
reverse
order
of
Removal.
When
i;etting
the
instrument
into
the
top
half
and
when
installing
the
bottom
half,
be
sure
the
instrument
settles
onto
the
plastic
guide
posts
so
the
cabinet
fits
together
completely
without
being
forced.
After
setting
the
instrument
into
the
top
half,
be
sure
the
power
I ine
cord
and
probe
lead are
properly
routed
and
placerl in
their
respective
cabinet
exit
slots
before
installing
the
bottom
half
(see Figure
4-4).
Install
the
rear-panel
compartment
cover
and
securing screws. A suggested
method
for
installing
the
rear panel
cover
is
to
install
and
lightly
tighten
the
screws,
then
insert
the
cover
hinge
into
its
respective
hr'es
and
tighten
all
the
screws.
BATTERY
REMOVAL.
To
remove
the
batteries,
remove
the
cabinet,
(see
Cabinet
Removal),
set
the
instrument
on
its
top,
disconnect
the
battery
lead,
and
remove
the
battery
,·
etainer
hold-down
screw.
Remove
the
battery
retainer
and
batteries,
then
tilt
the
instrument
up
on
its side nd
remove
the
other
battery
retainer.
~
Do
not
set the batteries on a metal surface
as
the
bottoms
are
at
a one cell potential
diff
Prence
and one
of
the cells will
be
shorted and destroyed.
Also, the cell tab connected to pins 1 and 3
of
P444
may
be
long enough to touch the other
tab on the cell which will short
out
the cell and
destroy it.
To
prevent this problem, the negative
tab
of
this cell
is
folded over ¼ inch and soldered
before leaving the factory.
It
is recommended
this same procedure
be
followed
if
other than
a direct replacement battery pack is used.
BATTERY
REPLACEMENT.
Replace
the
battery
in
the
reverse
order
of
Removal. Be
careful
not
to
overtighten
the
battery
retainer
hold-down
screw.
A/D
CONVERTER
BOARD
REMOVAL.
To
remove
the
A/D
Converter
Board,
r
emove
the
cabinet
and
batteries
(see
Cabinet
Removal
and
Battery
Removal),
then
proceed
as
follows:
@
Maintenance-213
Service
1.
Turn
the
instrument
over
on
its
bottom
and
remove
the
two
nuts
holding
the
A/D
Converter
Board
to
the
Line
Converter
Chassis (see Figure 4-
2).
2.
Gently
remove
the
A/D
Converter
Board by I ifting it
up
and
free
of
the
terminal
pins.
Remove
the
electrical
contact
(see Figure 4-7)
and
set
it aside
for
reinstallation.
AID
CONVERTER
BOARD REPLACEMENT.
Replace
the
A/D
Converter
Board in
the
reverse
order
of
Removal.
Be
sure
the
electrical
contact
is
properly
installed (see Figure
4-7).
Be
careful
not
to
bend
the
terminal
pins
on
reinsertion
of
the
board.
Also,
make
sure
all
the
pins
enter
their
re-
spective
terminal
pin
sockets.
CRT
REMOVAL.
To
remove
the
crt
assembly
(crt
and
shield)
complete
the
Removal
steps
of
all
preceding
compo-
nents,
then
proceed
as follows:
1.
Disconnect
the
crt
base
socket
and
the
three-terminal
connector
holder
just
below
and
to
the
left
of
the
crt
base
socket.
2.
Gently
pull
the
crt
assembly
toward
the
front
of
the
instrument
and
out
of
the
crt
retainer
ring.
If
the
assembly
is
very
tight
in
the
ring,
gently
rock
it
back
and
forth
while
pulling
it
out.
Do
not
rotate
the
assembly
in
the
retainer
ring
over
about
1
/8
inch as
there
is
a
solder
spot
on
the
crt
shield
which
is
located
within
the
retainer
ring
slot.
Rotat-
ing
the
assembly
beyond
these
I imits
may
loosen
the
solder
connection
or
damage
the
crt
retainer
ring.
Disassembly.
To
disassemble
the
crt
assembly,
proceed
as
follows:
WARNING
I
Use
care when handling a crt. Protective clothing
and safety glasses should
be
worn. A void striking
it
with any object which might cause
it
to crack
or implode. When storing a crt, place
it
in
a
protective carton or set
it
flat on a smooth surface
with a
soft
mat
under the faceplate edge.
1.
Remove
the
shield-lead
terminal
connector
from
the
three-connector
terminal
connector
holder
by
bending
the
top
part
of
the
holder
away
from
the
connector
and
remov
-
ing
the
connector
from
the
holder
(see Figure
4-10).
2.
Gently
pull
the
crt
completely
ou
t
of
the
crt
shield.
Re-
move
the
crt
support
ring
and
lay it aside
for
reassembly.
4-5
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