Marantz 4230 - Dolby FM Usage; Playback Usage; Record Modes; Off Position

With the DOLBY Switch placed in “OFF” position, the Meter will be used as a SIGNAL-
STRENGTH meter; in all other positions asa DOLBY CAL LEVEL meter.
7.1 Dotby 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 Dolbyized 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 Dolbyized signal from the tape will be heard.
7.5 Record 1!
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 controls
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 SWITCH
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 DE-
EMPHASIS switch provided on the rear of Model 4230 is used for switching the time constants.
After the permission of Dolbyized FM broadcasting, set the switch to 25uS position. This
automatically change the time constant to 75uS while the DOLBY switch is placed in other than
DOLBY FM positions (namely normal FM broadcast position), thus, the de-emphasis time
constnat for each normal and Dolbyized FM reception wil! be correctly set.