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Model 5254C
Section
V
f.
The
Multiplier
Amplifier alignment
procedure
(Paragraph
5-37) should
be
performed
after
replac-
ing
Harmonic
Generator Assembly.
5-26.
HARMONIC SELECTOR CAVITY
.
5-27.
No
attempt should be
made
to
repair
the
Har-
monic
Selector Cavity;
it
should
be replaced
as
a
unit.
To remove
the cavity,
see
Figures 8-2 and
8-3
and
proceed
as
follows:
a.
Remove
Multiplier
Amplifier
Assembly
as des-
cribed
in
Paragraph
5-22.
b.
Remove
the four
screws
that
secure
cavity
plug
assembly (MP3)
and
remove
cavity
plug and
cavity
output cable.
c.
Unscrew
knob
set
screws
and
remove
knob.
d.
Remove
the
four
screws
that
secure mixing
frequency
dial
and
remove
dial.
e.
Remove
the
five
Harmonic
Selector Cavity
mount-
ing
screws.
Remove
cavity
by
sliding to
rear and
lifting
it
out
through
the
left
side.
f.
To
replace
this
assembly reverse
the
procedure
used
in
steps a
through
e.
g.
All
replacement
Harmonic
Selector Cavities are
adjusted
at
the
factory
for
optimum
performance.
How-
ever,
if
a
general operation
check
is
desired,
and
in-
cabinet
performance check
is
given
in
Table
5-4.
5-28.
MIXER ASSEMBLY
A3.
5-29.
No
attempt should be
made
to
repair
this
as-
sembly;
it
should be replaced as a
unit.
To remove
the
assembly, see Figure
5-2
and proceed
as follows:
a.
Remove
the four
screws which
secure
top plate
(MP6)
and
remove
top
plate.
b.
Disconnect black wire
to
meter from ground
lug-
on
MP14
and white wire
to
meter from
capacitor
C3
on
MP14.
c.
Remove
screw
securing
aluminum
spacer rod
(MP10)
to
plug-in guide
(MP9)
on
right side
of
instru-
ment.
Unscrew
spacer
(MP10) from
front panel.
d.
Remove
the
twelve
screws
that
secure
amplifier
side plate
(MP12) and
remove
side
plate.
e.
Disconnect,
orange wire
from
A3R4
and
blue
wire
from A3R3.
f.
Slide
machined
amplifier
shield
to
rear and
out
the right side to
make
mixer
(A3)
and
mixer
securing
screws
accessible.
See Figure
8-4.
g.
Remove
the four
mixer
securing screws.
Re-
move
mixer
by carefully
pulling
it
out
of its
cavity
in
MP14
(machined
amplifier
shield)
.
h.
To
replace
the
Mixer Assembly
A3,
reverse
the
procedure used
in
steps a
through
g.
i.
The Mixer
Balance
adjustment,
Paragraph
5-40,
procedure
should be
performed
after
replacing
the
Mixer Assembly
A3).
5-30.
FILTER
ASSEMBLY
A4.
5-31.
To remove
Filter
Assembly
A4, see
Figure
5-2
and
proceed
as
follows:
a.
Remove
Mixer Assembly A3
as
described
in
Paragraph
5-28.
b.
Pull the Filter
Assembly
out
of its
cavity
in
MP14
with
a pair
of
longnose
pliers.
c.
To
replace
this
assembly reverse
the
procedure
used
in
steps a and
b.
5-32.
VIDEO AMPLIFIER
ASSEMBLY
A5.
5-33.
To remove
Video Amplifier
Assembly
A5,
see
Figure 5-2 and
follow
this
procedure:
a.
Remove
the
twelve
screws
that
secure
the
amp-
lifier
side plate
(MP12)
and
remove
side
plate.
b.
Disconnect
the
following wires:
1)
the
white
wire
from
capacitor C3;
2)
the
red
wire
from
capacitor Cl;
3)
the violet
wire
from
capacitor C2; and
4)
the
two
leads
from
the
video amplifier
output cables.
c.
Remove
the five
Video Amplifier securing
screws
and
remove
the
Video Amplifier
Assembly
A5.
d.
To
replace
the
Video Amplifier
Assembly A5
reverse
the
procedure used
in
steps
a
thru
c.
e.
The Mixer
Balance Adjust
control
is
on
the
Video Amplifier Assembly.
The
replacement
of
the
Video Amplifier
Assembly
necessitates
the adjust-
ment
of
the
Mixer Balance
in
Paragraph
5-40.
f.
All
replacement Video Amplifier Assemblies
are adjusted
at
the
factory
for
optimum
performance.
However,
if
general operation check
is
desired, an
in-cabinet
performance check
is
given
in
Table
5-4.
5-34.
METER REPLACEMENT
PROCEDURE.
5-35.
To remove
level indicator
meter, see Figure
5-2 and
proceed
as follows:
a.
Remove
the
four
screws
that
secure
the top
plate
(MP6)
and
remove
the top plate.
b.
Remove
the
four
screws
that
secure
the
side
plate
(MP7)
and
remove
the side
plate.
c.
Remove
the
three
screws
securing
the
three
aluminum
spacer rods (MP10).
d.
Unscrew
the
knob
set
screws
and
remove
the
knob.
5-3
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