Marantz 4230 - Dolby FM Preset Level Controls; Explanation of the Dolby Processing Chart

Next,
adjust
the
semi-fixed
resistor
RL12
for
580mV
output
level
when
the
DOLBY
switch
is
set to the OFF position. Check the 400Hz output signal level after the adjustment of the level
setting semi-fixed resistors RL11 and RL12. The output level must be precisely 580mV since
it is a reference level of the Dolby circuit.
23.
ALIGNMENT
PROCEDURES
OF
DOLBY
FM
PRESET
LEVEL
CONTROLS
Connect
an
FM
signal
generator
to
the
FM
antenna.
Set
the
signal
generator
for
400Hz
50%
modulation.
Set
the
FM
signal
generator
to
98MHz
and
the
DOLBY
switch
to
the
OFF
position.
Turn
the
Tuning
knob
on
Model
4230
until
it
tunes
to
the
98MHz
signal
from
the
FM
signal
generator.
Then,
set
the
DOLBY
switch
to
the
DOLBY
FM
position,
and
adjust
the
FM
preset
level
controls
RCO5
and
RCO6
so
that
the
DOLBY
LEVEL
meter
may
point
the
Dolby
level.
Change
over
the
METER
switch,
and
perform
this
adjustment
for
both
R
and
L
channels.
24.
EXPLANATION
OF
THE
DOLBY
PROCESSING
CHART
This
chart
shows
the
condition
of
the
signals
available
at
the
speakers
(SPKRS)
and
at
the
TAPE
MONITOR
OUT
terminals
as
a
function
of
different
control
settings.
To understand the chart refer to the symbols below:
—
Represents
a
signal
which
has
not
been
applied
to
either
Record
or
Playback
Dolby
circuits.
The
relative
amplitudes
of
all
audio
frequ-
encies
remain
unaltered
at
all
levels.
—
Represents
a
signal
which
has
been
processed
by
the
Dolby
Record
circuit.
The
relative
amplitude
of
the
high
frequencies
is
increased
at
low
signal
levels.
—
Represents
a
signal
which
has
been
processed
by
the
Dolby
Playback
\
circuit.
The
relative
amplitude
of
the
high
frequencies
is
decreased
at
low signal levels.
——
Represents
a
signal
which
has
been
processed
by
both
the
Record
and
the
Playback
Dolby
circuits.
These
circuits
are
complementary.
Therefore,
relative
amplitudes
of
all
audio
frequencies
are
restored
to
their
original
values.