Sony TA-2000F - Page 7

Stage/Control Function
the
mechanical
center
of
move-
ment,
a
special
potentiometer
having
a
conductive
coating
over
half its element length is used.
VOLUME
The
balanced
input
signals
from
control
BALANCE
control
VR7
is
fed
VR8
to
VOLUME
contro!
VR8,
which
regulates the signal applied to
the following tone-control cir-
cuit or output circuit.
Tone Amplifier Section
This three-stage amplifier has
basically flat response, and pro-
vides 20 dB voltage gain to com-
pensate for tone-control insertion
loss. It also isolates the volume-
control and tone-control circuits
to eliminate mutual interference.
The input signals are amplified
by Q501 and Q502, and then
applied to source follower Q503.
Bias voltage for Q501, Q502
and Q503 is determined by the
current flow in their respective
source resistors. Negative feed-
back is applied from the source
circuit of Q503 to the source
circuit of Q501 through C505,
R509, and C506 to obtain a
flat and wide response. Tone-
amplifier-1’s output is fed to
an RC-type tone-control circuit
through TONE CANCEL switch
S5 when S5 is set to “ON”.
Tone Amplifier
Q501, Q502
Q503
Bias circuit
TONE CANCEL
SW SS
Ly ey telele) s
Stage/Control Function
Tone Control Section
All inputs are applied this circuit
when TONE CANCEL switch
S5 is set at ON. Fig. 1-2 shows
the simplified circuit of tone
control incorporated with the
treble and bass turnover switches.
TREBLE control
' $6
Increases or decreases the
amount of high-frequency com-
ponents by switching the resis-
tors connected to S6 in steps.
TREBLE
TURN-
S8
selects
the
specified
turn
OVER
FREQU-
over
frequencies’
(2.5
kHz
or
ENCY
switch
5
kHz).
Refer
to
Fig.
1-3.
BASS
control
Increases
or
decreases
the
S7
amount
of
low
frequency
com-
ponents
by
switching
the
resis-
tors connected to S7 in steps.
R1110k
To
TONE CANCEL
sw
BASS
Control
SW S7
Q SW
TREBLE
Control SW
Sé
flat amplifier-2
a=)
Simplified tone control network
Fig. 1-2.
TABLE 1-3. OUTPUTS
L-CH
L+R
POSITION OUT
STEREO L+R
L+R L+R
rh
L
L+R
CENTER
HEADPHONE
RECOUT-1,
2,
MOE
E
SCE
CHANNEL
OUT;
REC/PB
OUT;
Lise
aa
tee
[tee
[ier]
tee
|
ae
a
L+R L+R L+R
L
R
L L R L