Technics ST-9038 User Manual

PART
II
CIRCUIT
FOR START AITÐ STOP PULSE
GENERATION
tN
AUTO
TUNTNG,
AND
ADJACENT C¡RCUITS
2-2-1
Outline of
auto tuning
MPX
The automatic tuning is
done
by the
frequency
codes of
the
programmable
counter. When
the auto
tuning
button
ís
pushed,
the
clock
pulse
oscillator
circuit
operates
and lC
4029C
starts
counting.
As the
desired
station is
approached,
a speed
down
signal is
generated
to lower
the clock
pulse
frequency.
ln
other
words, the
scanning
speed
is reduced.
After that,
the
stop signal is
generated
at
the exact
tuning
point
to stop
the clock oscillation.
Thus, the
scanning
stops and the
signal
is
received
at the
exact tuning
point.
This
is
the
basic
principle
of
auTo tuning.
The detailed
description
is
given
in the following.
TR909
R129
1o 4O29C
+
Vcc
t
o
o
ü
2-2-2
r--
Clock
.q4
AT button
TR 109
pulse
oscillator
circuit and
adjacent circuits
--
- -
-
--r
6 +Vcc
tc912
I
D918
I
TR908
Ð927
.-
/
R935
D91 6
D115
R 156
B 155
off
fine
f
ine
stand
s2-2
ard
r---
+Vcc
Latch
+Vcc
C lock
generâto
r
c¡rcu¡t
_I
Stop
signal
TR105
¿
J
3.1v
z1
Speed down
signal
TFì908
base
TFì908
em¡tter
o
3V
o
o.6v
Front end
l'F
Amp.
Programmable
counter
Sp€ed
down
Stop
ABCDE
ABCDE
Counte
r 4O29C etc.
Clock
generator
D9t 5
919
c91 3
D930
R938
R937
4,
V V
Wave
of clock generator
ló
-
o.
Time
t

Technics ST-9038 Specifications

General

Brand	Technics
Model	ST-9038
Category	Tuner
Language	English