Marantz 112 - Page 7

4. AM ALIGNMENT PROCEDURES
4.1 AM IF Alignment
(1) Connet a sweep generator to J206 and an alignment scope to the test point © .
(2)
Rotate
each
core
of
the
IF
transformers
L205
and
L206
for
maximum
height
and
flat
top
symmetrical
response.
4.2 AM Frequency Range and Tracking Alignment
(1)
Set
an
AM
signal
generator
of
515kHz.
Turn
the
tuning
capacitor
fully
closed
(place
the
tuning
pointer
at
the
low
end.)
and
adjust
the
oscillator
coil
L204
for
maximum
audio
output.
(2)
Set
the
signal
generator
to
1650kHz.
Place
the
tuning
pointer
in
the
high
frequency
end
and
adjust
the
oscillator
trimmer
on
the
oscillator
tuning
capacitor
for
maximum
audio
output.
|
(3) Repeat Steps (1) and (2) until no further adjustment is necessary.
(4)
Set
the
generator
to
600kKHz
and
tune
the
tuner
to
the
same
frequency
and
adjust
the
slug
core
of
the
AM
ferrite
rod
antenna
and
RF
coil
L203
for
maximum
output.
(5)
Set
the
generator
to
1400kHz
and
tune
the
tuner
to
the
same
frequency
and
adjust
both
trimming
capacitors
of
the
antenna
and
RF
tuned
circuit
for
maximum
output.
(6) Repeat Steps (4) and (5) until no further adjustment is necessary.
Note:
During
tracking
alignment
reduce
the
signal
er
output
as
necessary
to
avoid
AGC action.
5. FM ALIGNMENT PROCEDURES
(1)
Connect
an
FM
signal
generator
(FM
SG)
to
the
FM
antenna
terminals
and
an
oscilloscope
and
audio
distortion
analyzer
to
the
output
jacks
on
the
rear
panel.
(2)
Set
the
FM
SG
to
87.0MHz
and
provide
about
3
to
5uV.
Place
the
tuning
pointer
at
the
low
frequency
end
by
rotating
the
tuning
knob
and
adjust
the
core
of
the
oscillator
coil
L104
to
obtain
maximum
audio
output.
(3)
Set
the
FM
SG
to
108.5MHz
and
provide
about
3
to
5uV
output.
Rotate
the
tuning
knob
and
place
the
tuning
pointer
at
the
high
frequency
end
and
adjust
the
trimming
capacitor
C123
for
maximum
output.
.
(4) Repeat Steps (2) and (3) until no further adjustment is necessary.
(5)
Set
the
FM
SG
to
90MHz
and
tune
the
tuner
to
the
same
frequency.
Decrease
signal
generator
output
until
the
audio
output
level
decreases
with
decrease
of
the
generator
output.
Adjust
the
antenna
coil
|.101,
RF
coils
L102
and
L103
and
IF
transformer
L105
for
minimum
audio
distortion.
(6)
Set
the
FM
SG
to
106MHz
and
tune
the
tuner
to
the
same
frequency.
Adjust
the
trimming
capacitors
C101,
C102
and
C103
for
minimum
distortion.
(7) Repeat Steps (5) and (6) until no further adjustment is necessary.
(8) Adjust the secondary core (upper) of the discriminator transformer L201 so that the
center
tuning
meter
pointer
indicates
its
center
at
no
signal
applied.
Set
the
FM
SG
to
98MHz
and
increase
its
output
level
to
1KuV
and
tune
the
tuner
to
the
same
frequency
so
that
the
center
tuning
meter
pointer
indicates
its
center.
Adjust
the
primary
core
(lower) of L201 for minimum distortion.
5.1 Stereo Separation Alignment
(1)
Set
an
FM
signal
generator
(FM
SG)
to
srevide
1KuV
at
98
MHz.
Tune
the
tuner
to
the
same
frequency
so
that
the
center
tuning
meter
pointer
indicates
its
center.
Then
turn
off
the
modulation
of
the
FM
SG,
connect
a
frequency
counter
to
the
test
point
R304
(point
®
)
and
adjust
R307
so
that
the
frequency
counter
may
precisely
read
19kHz.
(2)
Modulate
the
FM
SG
with
the
stereo
composite
signal
consisting
of
either
L
or
R
channel
(of course, the pilot signal must be included).