Marantz SD9000 - Page 14

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3.6 Tape slack removal circuit
10v
CASSETTE P
so2l
R591
R693
PLAY
PAUSE
TO
PLAY
pace FAST Selenoid driver
MOO2 Real motor
Reel motor driver
Sg ee ee i Servo
rit amplifier \
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If the tape in the cassette is slack, it can result in tangl-
ing of the tape in the tape drive mechanism. The
SD8000 is equipped with a tape slack removal circuit
which removes any slack tape automatically when a
cassette is loaded in the tape deck or when the power
switch is set to ON (not when backup is power ON).
Refer to Fig. 3.9.
When the power of the tape deck is set to ON without
a cassette loaded, the cassette IN switch (S021) is open
and 0547 is OFF, but 0548 is ON.
When a cassette is loaded, S021 is closed and 0547 turns
on. The base of 0548 is grounded through C524 and
Q548 turns off for about 1 second.
While 0548 is OFF, a high level signal is output from
the collector of 0548 to perform the following func-
tions:
(1) Q515 is switched ON via 0574 and R558 to drop
the PLAY signal level to L so that the deck is not
set in the PLAY mode until the slack in the tape is
removed.
(2) QMO9 is switched ON through R691. Therefore, the
voltage divided by RM11 and RM12 is applied to
the base of QM10, then the emitter output voltage
of OM10 drops to about 8V (at unloaded time). As
a result, the torque of the reel motor is lowered to
prevent the tape from being wound more than
necessary.
(3) QMO7 is switched ON via R562, 0579 and RM10.
QMO3 and OQMO04 are also ON and the same direc-
tion as the REW mode.
The left and right reel disks are braked while the
tape slack is being removed, but less braking is ap-
plied to the left reel base than to the right reel base
so the tape is wound onto the left reel with a low
driving torque as the slack tape is removed.
When the power is turned on with a cassette loaded
(for timer recording, etc.), slack tape is also re-.
moved in the same way.
When the PLAY, FF, REW or STOP button is pres-
sed during the tape siack remova! operation, the fol-
lowing functions are performed:
13
Fig. 3-9 Tape slack removal circuit
(4) PLAY button
Q515 is switched ON and the PLAY signal level is
reduced. Slack tape is removed and the tape is set
to the PLAY mode after 0522 turns OFF.
(5) FF button
Q549 is switched ON via R579, releasing the tape
slack removal operation. The deck is set in the FF
mode.
(6) REW button
The deck is set to the REW mode immediately.
The torque of the reel motor remains low during
the slack tape removal operation.
(7) STOP button
The slack tape removal operation contrinues.
3.7 Tape Speed Selector Circuit
The tape speed in the PLAY or REC/PLAY mode is
determined by the speed of the capstan motor (M001).
This motor is servo controlled by its FG (frequency
generator). The speed is selected by changing the series
resistor in the frequency generator.