Maintenance-2445A/2455A Service
4.
Disconnect
the
two power-supply multipin connectors
(P121
and
P122)
from
the
side of the Power Supply
assembly.
5.
Disconnect the three ribbon-cable connectors
(P411,
P511,
and
P512)
from the bottom of the Main board.
NOTE
See
·warning· under CRT Removal before
proceeding.
6.
Disconnect the vertical
and
horizontal deflection
leads from the
neck
pins of the
CRT.
Access
is
via
holes
in
the Main board.
Use
long-nose pliers to disconnect the
pins
by
gently pulling straight
up
on
the connectors. Avoid
putting side pressure
on
the metal-to-glass
seal
of the
CRT
neck
pins.
7.
Desolder
the
rear-panel
BNC
connector leads from
the
BNCs.
Unplug the
CH
2
OUT
cable
(P105)
from the
Main board,
and
remove its
cable
retaining clamp.
8.
Disconnect the flex-circuit connector
(P120)
for the
CRT
controls from the Main board.
9.
Disconnect
the
two-conductor connector
(P181)
for
the
Scale
Illumination board near
the
ASTIG
and
the
SCALE ILLUM controls.
10.
Remove
the
STEP/AUTO jack
(J12)
retaining nut
from
the
rear plate after desoldering its wire from the Main
board using correct
vacuum
desoldering techniques.
Remove
the jack.
11.
Turn
the long extension shaft
(see
Figure
6-3)
CCW
and
unsnap it from the pivot bracket at the rear middle of
the
Main
board, sliding it out of the bracket sideways.
~
Do
not pull on the power switch push button
or
it
will
be
damaged.
6-30
12.
Remove
the power switch push button mounting
screw (item
A)
shown
in
Figure
6-3.
Separate the long
extension shaft from the short extension shaft at point B
by inserting a small screwdriver tip
in
the slot while pulling
out
on
the bracket
at
point
C.
Remove
the
screw (item
D)
and
slide the long extension shaft out the rear of the front
frame.
13.
Remove
the two screws holding the Attenuator sup-
port bar
and
remove the bar.
14.
Remove
the six screws holding the Attenuator
assemblies
and
the
CH
3
and
CH
4 input connectors to
the front subpanel.
15.
Remove
the Main board mounting screws (ten
screws total) securing the Main board to the chassis.
16.
Lift the rear of the
Main
board away from the
chassis to unplug
J191
and
separate the
Main
board from
the
High
Voltage board.
When
the
plug
pins
are completely
disengaged
and
the
rear
of
the board clears the rear
frame, slide the
Main
board rearward out of the front sub-
panel.
Lift the Main board (with attached
Delay
Line)
clear
of the instrument while working the power supply cables
through the slot
in
the
chassis.
To reinstall the
Main
board, perform the
reverse
of the
preceding instructions.
AS-Scale
Illumination Circuit Board Removal
NOTE
See
·warning" under CRT removal instructions
before proceeding.
Removal
of the Scale-Illumination Circuit Board is
accomplished by the following steps:
1 .
Remove
the instrument Cabinet
as
described
in
that
procedure.
2.
Remove
the front decorative trim
ring
as
described
in
the
A6-Front
Panel
board removal procedure.
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