Onkyo TX-7230 - Muting Circuit

TX-7230
Pin
No.
Terminal
Description
ie
se
posta
lie
tiane
ae
tes
:
|
;
L/D
Ouiput
indication
switching
input
terminal:
Fluorescent
display
at
the
low
level,
and
/
LED
display
at
the
high
level.
|
:
+
zs
|
2
Data
Tuned
frequency
data
input
terminal:
Input
from
the
system
controller
LSI
to
the
serial.
34
CKL.CK2
Tuned
frequency
data
input
control
timing
input
terminal:
|
;
ops
st,
Transferred
simultaneously
with
data
from
the
system
controller
LSI.
Es
Ss
eee
5
1/0
Segment
drive
output
terminal:
Sets
the
number
of
display
digit
for
FM
(100MHz)
and
/
AM
(1
,000kHz)
reception.
L
at
ae
6-12
3.93
Seven
segment
drive
output
terminals:
Sets
the
number
of
display
digit
for
FM(1OMHz)
;
a8
and
AM
(100kHz)
reception.
zl
13.
15-20
2-92
Seven
segment
drive
output
terminals:
Sets
the
number
of
display
digit
for
FM
(1MHz)
as
ave
and
AM
(10kHz)
reception
.
.
.
soe
.
34.97
fi
Seven
segment
drive
output
terminals;
set
the
number
of
display
digit
for
FM
(100kHz)
ew
8
and
AM
(1kHz)
reception
[
oe
14
Vec
Power
source
terminal
“|
t
28
Gnd
Ground
|
7.
Muting
circuit
The
muting
circuit
operates
in
the
following
cases.
1.
Q103
FM IF
SYstem
from muting output of controller IC
To output
Q207
Muting
Switch
a109, Q110
Schmidt
Trigger
To output
Switch
0201
Stereo decoder
(SOkHz
step)—
are
output
at
pin
12
through
the
AND
While
pin
28
of
the
controller
IC
outputs
the
high
level,
Q207
and
Q208
are
turned
on
and
muting
is
closed
in
the
following
cases:
(1)
While
the
the
manual
UP/DOWN
switch
is
being
held
down,
(2)
When
a
station
in
the
memory’
is
recalled,
and
(3)
While
a
radio
station
is
being
received
using
auto
search
tuning.
.
When
an
FM
station
is
not
being
received
(and
the
mut-
ing
switch
is
on).
The
IF
level
in
the
FM
IF
system
(set
at
R120
so
muting
is
opened
at
17
dBf
(low
position))
and
zero
point
detec-.
tion
circuit
(tuning
point
55kHz
(100kHz
step):
30kHz
circuit.
When
a
station
is
tuned,
the
output
goes
to
the
low
level.
When
output
goes
to
the
low
level,
Q109
is
turned
off,
Q110
is
turned
on
and
Q207
and
Q208
are
turned
off,
so
muting
is
opened.
At
the
same,
pin
16
of
stereo
decoder
Q201
goes
to
the
low
level,
so
the
VCO
oscil-
lator
starts.
—12—