Marantz 4270 - Page 10

The signal fed from the Dolby P.W. Board (P600) comes to JL04 and is rectified through
HLO6G. The rectified output at JLO6 is led to the meter MO04.
7. DOLBY SWITCH
This switch sets the Dolby noise-reduction circuit for record or playback and also switches
the Meter Mode from AM or FM SIGNAL STRENGTH to DOLBY CAL LEVEL, or vice-versa.
With the DOLBY Switch placed in “OFF” position, the Meter will be used as a SIGNAL-
STRENGTH meter; in all other positions as a DOLBY CAL LEVEL meter.
7.1 Dolby FM
This position is used for listening to Dolbyized FM broadcasts. The Dolby FM level has been
pre-adjusted at the factory.
7.2 Play
This position is used to play back a Dolbyized source (except FM).
7.3 Off
With this position, the Dolby circuit is by-passed and the input signals are directly applied to
both TAPE MONITOR OUT jacks and amplifiers.
7.4 Record |
For making a Dolbyzied recording from an in-coming ‘‘flat’’ (non-Dolbyized) signal. When
the MONITOR switch is in the SOURCE (out) position, the ‘flat’ signal will be heard. When the
MONITOR switch is in the TAPE (in) position, the Dolbyzied signal from the tape will be heard.
7.5 Record II
For making a “‘flat’’ (non-Dolbyized) recording from an in-coming Dolbyized signal.
Regardless of the position of the MONITOR switch, a “flat’’ signal will be heard.
8. RECORD LEVEL (L) (R)
These knobs control the record level of the signals to be recorded through the Dolby unit.
Adjust
the
knobs
so
that
the
Level
Meter
pointers
of
the
tape
recorder
do
not
exceed
the
OVU
level.
9. PLAY CAL. (L) (R)
These knobs adjust the playback outputs from a tape deck to the proper Dolby level.
10. DOLBY FM PRESET LEVEL CONTROLS
These
factory-adjusted
controls
govern
FM
output
level
to
the
Dolby
circuit.
These
control
are for the use of a qualified technician only.
11. 400Hz TONE SWITCH
This is used for calibration of the record input level of the tape deck. When the switch is
depressed,
the
built-in
oscillator
operates
and
a
sine
wave
signal
output
of
580mV
will
be
applied
to
the
four
TAPE
MONITOR
OUT
jacks.
12. FM DE-EMPHASIS SWTICH
At
present
both
normal
and
Dolbyized
FM
broadcast
programs
are
being
transmitted
with
pre-emphasis
time
constant
of
75
microsecond.
However
if
the
Dolbyized
FM
broadcasting
is
approved
by
F.C.C.,
this
pre-emphasis
time
constant
for
Dolbyized
FM
broadcast
will
be
changed
to
25
microsecond.
The
FM
DEEMPHASIS
switch
provided
on
the
rear
of
Model
4270
is
used
for
switching
the
time
constants.
After