Marantz 4415 - PHONO AND PRE-AMPLIFIER FUNCTIONS

3.3
Suggestion
for
Trouble
Shooting
of
FM
Tuner
3.3.1
Symptom:
No
FM
Reception
First
turn
on
the
power
switch
and
try
to
tune
FM
stations.
Rotate
the
fly-wheel
tuning
knob
slowly
and
observe
the
FM
signal
strength
meter.
If
the
signal
strength
meter
deflect
at
several
frequencies
received,
the
tuner
circuits
preceding
the
discriminator
circuit
may
have
no
failure.
When
no
reading
is
obtained
in
the
meter,
check
FM
local
oscillator
circuit,
using
a
RF
VTVM.
The
normal
local
oscillator
voltage
is
one
or
two
volts
(rms)
at
the
tuning
capacitor,
depending
on
the
tuning
capacitor
position.
If
the
local
oscillator
voltage
is
normal,
next
check
all
voltage
distribution
in
the
FM
Front
End
and
IF
amplifier
unit
and
compare
them
with
those
shown
in
the
circuit
diagram.
When
signal
strength
meter
deflects
but
no
sound
is
obtained,
check
audio
circuits,
using
high
sensitive
oscilloscope.
3.3.2
Symptom:
No
Stereo
Separation
Connect
a
FM
RF
signal
generator
output
modulated
by
a
stereo
modulator
to
the
rear
FM
ANTENNA
terminals,
and
check
the
stereo
beacon
is
turned
on
or
not.
If
not
turned
on,
check
for
19
KHz
pilot
signal
and
38
KHz
switching
signal,
using
an
oscilloscope.
4. PHONO AND PRE-AMPLIFIER
Signals
from
the
PHONO
jacks
are
applied
to
the
phono-amplifier
mounted
on
P300.
The
amplified
and
RIAA
equalized
phono
signals
and_
signals
from
the
tuner
section
and
the
TAPE/AUX
jacks
are
applied
to
the
selector
switch
which,
in
turn,
leads
the
selected
signals
to
the
TAPE
MON
switch
and
TAPE
OUT
jacks.
Applied
to
the
other
section
of
the
TAPE
MON
switch
are
signals
from
the
TAPE
IN
jacks.
The
TAPE
MON
switch
selects
the
signals
from
the
selector
switch
or
those
from
the
TAPE
IN
jacks
and
the
selected
signals
go
to
the
mode
switch.
Signals
are
then
mode
processed
by
the
mode
switch
and
its
associated
circuit
and
applied
to
the
tone
control
amplifier
through
the
volume
control.
The
bass
and
treble
controlled
signals
from
the
tone
control
amplifier
pass
through
the
balance
control
section
and
the
hi
filter
before
they
reach
the
main
amplifier.
4.1 Mode Switch
Mode
switch
SOO02
has
positions
of
on
2
CH,
DISCRETE,
VARI-MATRIX,
and
SQ
DECODER.
In
the
MONO
position,
all
input
signals
are
mixed
together
and
delivered
to
all
four
channels.
In
the
2
CH
position,
each
pair
of
input
signals
right-front.
(RF)
and
right-rear
(RR),
and
left-front
(LF)
and
left-rear
(LR)
are
mixed
together.
The
resultant
signals
(RF
+
RR)
and
(LF
+
LR)
are
delivered
to
the
pairs
of
RF
and
RR,
and
LF
and
LR
channels,
respectively.
In
the
DISCRETE
position,
each
channel
signal
is
separately
routed
to
the
corresponding
channel.
In
the
VARI-MATRIX
position,
2-channel
stereo
input
signals
are
converted
into
quadra-
phonic
signals
through
the
vari-matrix
circuit;
the
input
right
and
left
channel
signals
are
fed
directly
to
the
LF
and
RF
channels,
while
the
signals
to
the
LR
and
RR
channels
are
synthesized
from
the
2-channel
input
signals
under
the
control
of
the
dimension
control.
The
LR
and
RR
channel
signal
components
are
controlled
by
the
dimension
control
as
shown
below.
Dimension
Control
Setting
LR
Output
RR
Output
Minimum
(FCCW)
Center
Maximum (FCW)
When
the
dimension
control
is
set
to
the
minimum
position
the
LR
and
RR
channel
signals
become
monophonic,
to
the
center
are
stereophonic,
and
to
the
maximum
are
out
of
phase,
thus
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