When
K1
is
relaxed the
normal
speed windings are connected.
The
high
windings are connected
by
energizing
K1
by
turning
on
Q2
and
supplying
a ground path to
R6.
Transistor
Q2
can turn
on
by
connecting
its
base
through
CR5.
In
playback
units
terminal P
is
connected
directly
to ground.
In
record models,
this
point
is
connected to the record
logic
so
that
a
ground
is
supplied only in the playback
mode
(not
in
the record
mode).
The
other side of the
coil
of
K1
can
only ground through
CR7
and
Q5
in the play-
back
(run)
mode.
This
can
be
accomplished in
two
separate
ways.
When
the
front
panel switch
is
placed in the
ADVANCE
position
R6
is
connected
directly
to
CR?
to energize
K1.
The
cue tone sensors
on
the
Playback/Logic board receive a ground through terminal
15
to
mute
the 1
kHz,
150Hz,
and
8kHz sensors while enabling the 3kHz sensor.
Diode
CR6
prevents
the audio muting
circuit
at
terminal S
from
grounding.
The
unit
goes into
fast
forward
and
will stop
on
a stop cue tone.
The
program
material
on
the tape
is
not shut
off
from
the output
jack.
When
the switch
is
released,
K1
deenergizes
to
return the
unit
to
normal
speed.
When
equipped with the option
for
automatic
fast
forward
SCR
Q1
is
installed
as well as
driver
Q4
which
is
controlled
by
the
QI
150
Hz
cue
tone sensor
on
the Playback/Logic board.
When
the
150
Hz
QI
tone
is
present
the
QI
control
at
terminal B goes high
to
turn
on
Q4.
Relay
K2
energizes
providing a ground
for
the
QI
lamps
and
K2.
Relay
K2
energizes
to
close
the
normally
open
contacts
available
on
the remote control connector.
When
the
tone ends, the control goes
low
and
shuts
off
Q4.
A
positive
pulse
is
de-
livered
by
C10
through
CR3
and
S1
to the gate of
SCR
Q1.
This pulse turns
Q1
on
to ground
relay
K1.
Both
the cue
shift/mute
and
the audio
mute
buses
ground.
The
unit
goes
into
fast
forward
and
shuts
off
the audio output.
The
unit
remains in high speed
until
the stop tone
is
sensed
by
the 3
kHz
sensor.
When
the
unit
stops,
Q5
shuts
off
so
that
SCR
Q1
no
longer
can
conduct
current.
Q1
turns
off
to deenergize
K1
and
deactivate
the cue
shift/
mute
and
audio
mute
buses.
Manual
operation of the
ADVANCE
switch in the
automatic
fast
forward
mode
will turn
off
Q1
and
return
the
unit
to
normal
speed operation without stopping.
Relay
K3
associated with the
QII
8
kHz
cue sensor
works
in the
same
manner
as
K2.
When
the
QII
8
kHz
tone
is
present,
the base of
Q6
goes
high to turn
on
Q6
and
K3.
Contacts
on
K3
supply provide the
closure
available
on
the remote control connector.
When
the tone ends, the control
at
terminal A goes
low
to turn
off
Q8
and
K3.
4-13.
4-14.
RECORD
AMPLIFIER/BIAS
BOARD
CONFIGURATIONS
The
Record
Amplifier/Bias Board,
installed
only in record models,
contains the
program
track record
amplifiers,
the record input
transformers,
the
100
kHz
record bias
oscillator,
and
the cue
track
record
control.
Separate versions are manufactured
for
monophonic
and
stereophonic machines.
The
assembly
and
its
parts
are
shown
in Section
VI.
17
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