Technics ST-9038 User Manual

PART
TT
OPERATION
OF
THE TUNING COUNTER
TR105
collector
fo
Af
lspeed
down s¡gnal]
TB109
collector
Af
lstop
signall
3. Operation
of the tuning
counter
3-1 Operationaldescriptionof
lG's
When
the scan signal approaches,
voltage is
generated
at
pin
(9 of
4N377
having a wide-band
characteristic. Then, TR105 turns
ON
and
the
collector becomes
ground potential.
With TR105
turned ON,TR106
turns
OFF,and
D'105 is
reverse-
biased.
At the same
time,
pin
@
of 4N377 be-
comes OV at the
exact
tuning
point
as it is the
terminal of the muting signal. Also,
the frequency
band
is narrow as illustrated
at left. Therefore,
TR104 turns OFF and
D104 is reverse-biased at
the exact
tuning
point.
Thus, TR109
turns ON,
only when
D106
and
D104are
reverse-biased. This
results
in
emission
of the
stop
signal.
LJ-
o
ID
o
The
description of
the operation
of lC's is
given
prior
to
the
actual
circuit description.
To
fully
understand
the functions
and characteristics of the lC's,it
isvery important to learn
the contents
in
this
section.
SVI¡PD4029C
Presettable up/down
counter
This counter
gives
the
frequency
codes to the
programmable
frequency
dividers
74L5192
and
pPD861C
which
play
the
major roles of
the PLL
synthesizer.
The
counter
has two
functions as
mentioned below.
It counts the
clock
pulses
at the CK
(decimal
or
hexadecimal input),
and
its output is the
binary code
from
O¡
-
Oo
and
the carry
from
CO.
CK- Clock
input terminal
When clock
pulses
enter
this
terminal, the
counter
in the 4029C
starts
cou nti ng.
Cl- Carry
in
When this terminal
is
"H",
no counting
is
done
even when CK
has input.
Counting
is
done only
with this terminal aT.
"L".
OA
-
OD-
The number of
clock
pulses
counted
by the counter is in binary
or B.C.D.
code
B/D- Binary/Decade
This
terminal
is to
select
the mode
(hexadecimal
or decimal)
of the
counter
in
4029C.
The
counter
is
decimal al
"L"
and
hexadecimal
at
"H".
CO- Carry
out
On completion of counting up
(decimal
or hexadecímal)
or counting
down
of
the counter, clock
pulses
for one cycle are
put
out
to
(O).lLf
u/D-
up/down
The counter counts down with this terminal
at
"L",
and
counts
up at
"H".
o
-18-
cl
CK
P/Ê.
oD
oc
oB
oA
pPD4029e
co
UlD
B/D
B
DC
t

Technics ST-9038 Specifications

General

Brand	Technics
Model	ST-9038
Category	Tuner
Language	English