Maintenance-2445A/2455A Service
1 . Remove the instrument Cabinet as described
in
that
procedure.
2.
Remove the Vertical Bracket
as
described
in
that
procedure.
3.
Remove three screws
on
the rear
CRT
cover.
Remove
the cover.
4.
Unplug the CRT socket
by
gently prying the socket
evenly
on
both sides until the pins
can
be
disengaged.
Do
not apply side pressure
on
the socket.
wAa11111a
I
The
CRT anode lead and the output terminal
of
the
High-Voltage Multiplier can retain a high-voltage
charge after the instrument
is
turned off.
To
avoid
electrical shock, ground both
the
CRT anode lead
and the high-voltage lead to
the
main instrument
chassis. Repeat the grounding process several times
to fully dissipate the
charge.
5.
Disconnect the CRT anode
lead
connector
and
discharge it to chassis ground.
6.
Using long-nosed pliers, disconnect the horizontal
and
vertical deflection leads from the bottom of the CRT.
Pull
straight out
on
these connectors to prevent strain
on
the metal-to-glass seal. (Access to the connectors is
through holes
in
the Main board).
7.
Using long-nosed pliers, disconnect the vertical termi-
nation leads from the top of the
CRT.
Also disconnect the
CRT shield ground
lead
from the top of the
CRT.
8.
Remove the five screws securing the High-Voltage
Shield
and
remove the shield. If optional assembly cables
are
mounted
in
the shield's groove, it will
be
necessary to
loosen these cables from the option board enough to slip
the cover out underneath them.
6-32
9.
Disconnect the connector (P903) from the front of
the High-Voltage board. Note connector orientation for
reinstallation.
1
0.
Remove the front decorative trim ring
as
described
in
the AS-Front-Panel circuit board assembly removal
instructions.
11.
Remove the eight retaining screws from the CRT-
mounting
bezel
at the front of the CRT. Note the
difference
in
length of the screws for reinstallation.
Push
in
on
the four longer (outer) screws to disengage the CRT
retainers.
12.
Remove the CRT frame and black plastic gasket
from the front of the instrument, working the frame gently
from side to side to free it from the CRT (if required).
13.
Slide the CRT out of the instrument while feeding
the CRT leads through their respective holes
in
the CRT
shield
and
front subpanel.
NOTE
Once
the CRT is removed,
it
should be stored in
such a manner as to protect
it
from impact.
If
stored
face
down,
it
should be placed on a soft, nona-
brasive surface to prevent the CRT
face
plate from
being scratched.
To
reinstall the
CRT,
perform
the
reverse
of
the preceding instructions. Be certain the
two pins on
the
lower edge
of
the CRT frame align
with the hole and slot
in
the front subpanel
of
the
chassis. Tighten the shorter screws to
10
in-lb
of
torque before tightening any
of
the
longer screws.
Then
tighten
the
longer screws in sequence:
2 1
4 3
Screw number one aligns the CRT.
On
the third time
through the sequence, tighten each screw to 10 in-lb of
torque.
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