Onkyo TX-7230 - Auto Hi-Blend Switch Circuit

Pin No. | Symbol Terminal Description
bs { fe
Charge pump output of the phase detector which constitutes the PLL.
34 DOI High level is output when the divided oscillation frequency is high than
: the reference frequency. In the opposite case, low level is output.
{— —} Error output Floating occurs when the frequencies match. The output is applied to
the variable capacitor diode in the front end through low pass filter
35 DO2 Q704 and Q705. The output from both terminals is the same, but
only DOI is used.
{
36 TEST Test terminal Test mode at the high level.
+}
}..__-_-—
-
7 FM programmable “
37 FM IN counter input Connect to the prescaler output (Pin3 of Q701) |
38 PSC ra a control Output to the control the division ratio of the prescaler.
ie
AM
local
oscillator
:
‘
:
39
AM
IN
signal
input
Terminal
for
input
of
AM
broadcast
signal.
40
INH
Inhibit
input
Operates
normally
at
the
high
level.
Inhibit
status
at
the
low
level.
_. 4 1
.. int idsialigetasat Operates normally at the high level. At the low level, the internal status
a a is initialized.
ea? Mog eee le | ‘Pewee power terminal; : supplies 5V during the normal operation and
42 Yee Power stply 2.5V from the super capacitor (C712) for memory preservation.
be
table |.
E]
E2
ei
Bane
i
Frequency
Intermediate
Reference
(Pin
30)
(Pin
29)
pa
a
range
frequency
step
frequency
-+—--_—_—___--—_}. fp —
FM 87.5 ~ 108.0 MHz +10.7 MHz 100 kHz 25 kHz
0
l
foes
ht
ong
SO
U.S.A
AMI
520
~
1
710
kHz
+450
kHz
10kHz
10
kHz
ak eles | eeeseen
|
l
AM2
522
~
1710
kHz
+450
kHz
9kHz
9kHz
| FM +10.7MHz | SO kHz 25 kHz
fe a ee
]
0
Europe
|
MW
522
~
1611
kHz
+450
kHz
9
kHz
9
kHz
LM 153 ~ 360 kHz +450 kHz 1 kHz
_t
FM 76.0 ~ 90.0 MHz - 10.7 MHz 100 kHz
0 0 Japan i.
AM 522 ~ 1611 kHz +450 kHz 9 kHz
2. Auto Hi-blend switch circuit
The
Q103
FM
IF
system
incorporates
IC’s
with
a
built-in
IF
level
detector
with
a
13
pin
output.
If
an
input
above
38dB
enters
the
antenna,
Q205
is
turned
on,
and
Q721
is
turned
on,
the
Q722
and
Q202
are
turned
off
and the
high
blend
function
is
turned
off.
—9—