HP 5254C - CIRCUIT ADJUSTMENTS

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