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CHASSIS DESCRIPTION
F=OWER
SUFPI.-Y
The
power
supply
circuit
of
the
E3B
chassis
is composed
of
a
rectifier
smoothing
circuit,
an
oscillation
circuit,
a
control
circuit
and
an
output
rectifier
circuit.
The
AC
Input
voltage
is
full-wave
rectified
by
the
rectifier
smoothing
circuit,
and
an
astable
DC
voltage
is
generated
at
both
terminals
of
the
smoothing
capacitor
C320.
This
voltage
is
input
to
the
oscillation
circuit.
The
oscillation
circuit
is
provided
with
a
blocking
oscillator
circuit
that
switches
the
switching
transistor
Q323
ON
and
OFF,
and
an
osci I Iation
frequency
and
a duty
square
wave
pulse
are
generated
in
the
input
windings
according
to
the
operation
of
the
control
circuit.
A
square-wave
pulse
whose
size
is
dependent
on
the
turn
ratio
of
the
input
and
output
windings
is
obtained
in
the
output
winding.
This
is
rectified
in
the
output
rectifier
circuit,
and
the
desired
DC
voltage
is
obtained.
IF
&
DEFLECl_l
ON
The
IF
output
signal
from
the
tuner
passes
through
the
SAW
filter,
and
it
is
Input
to
pin
(6)
and
pin
(7)
of
IC180
and
is input
to
pin
(4)
and pin
(3)
of ICICO.
The
signal
input
to
the
IC180
passes
through
the
IF
amplifier,
video
detection
and
video
amplifier
circuits
and
it
is
output
from
pin
(22)
as
a
composite
video
signal.
The
output
signal
from
pin
(22)
also
passes
through
the
5.5
MHz
trap
circuit
of
X197,
and
it
is
input
to
pin
(6)
of
IC2A0.
The
signal
input
to
the
ICICO
passes
through
the
SIF
amplifier,
FM
detector,
volume
control
and
audio
output
circuit,
and
it
is
then
output
from
pin (15)
as audio
drive
signal.
The
sync. separation
circuit
separates
the
video
signals
to
vertical -
and
horizontal
-sync .signals
respectlvei
y.
The
horizontal-sync.
signal
passes
through
the
IC401
and
it
is
applied
to
the
gat!ng
circuit,
and
performs
the
horizontal
oscillation
trigger.
The
horizontal
oscillation
occurs
as
a
result
of
the
circuit
configuration
consist ing
of
C415,
R420,
VR411
and
pin
(15),
and
the
horizontal
free
oscillation
frequency
IS
adjusted
from
pin
(14).
VR41O
IS
for
adjustment
of
the
horizontal
centring.
The
separated
vertical -sync. signal
from
the
sync .-
separation
circuit
passes
through
the
vertical-
separation
circuit,
and
applied
to
the
trigger
divider
circuit.
The
horizontal
oscillation
pulse
and
input
vertical -sync .pulse
are
monitored
by
the
trigger
divider
circuit,
and
the
switching
(50Hz
/
60 Hz)
system.
The
vertical
amplitude
is
adjusted
for
50Hz
and
60Hz
automatically.
The
output
signal
from
the
trigger
divider
is
triggered
by
the
vertical
oscillation
circuit
consisting
of
R404,
C404
and
pln
(4),
and
vertical
drive
pulse
output
from
VR405
is for
changing
the
amount
of AC
feedback
applied
to
pin
(2)
and
for
adjustment
of
the
vertical
amplitude.
AUDIO
OUl_l=UT
<TDA1521>
The
audio
signal
output
from
pin
(13),(15)
of
IC850
is
input
to
pin
(l),(9)
of
IC390
and
passes
through
the
preamplifier
circuit
and
the
drive
clrcult,
after
that
it
is
input
to
the
audio
amplifier.
The
audio
amplifier
is
an
SEW
(single-ended,
push-pull)
OTL
type
and
outputs
to
pin
(4),(6)
to
drive
the
speaker
directly.
VI
DEO,
CHROMA&R.
G.B.
The
composite
video
signal
output
from
the
pin
(22)
of
IC180
passes
through
Q1C3,
Q5F2
and
Q5F5,
and
it
is
supplied
to
pin
(15)
of
IC270
as
the
luminance
(Y)
signal,
to
pin
(15)
of
IC200
as
the
chroma
signal.
The
luminance
signal
input
to
the
pin
(15)
of
IC270
is
applied
to
the
luminance
amplifier
and
the
contrast
control
circuit.
The
gain
control
(contrast)
is
applied
by
the
pin
(19)
as
DC
voltage,
and
this
signal
IS then
input
to
the
matrix
circuit,
The
DC
level
of
the
luminance
signal
can
be
varied
(brightness)
by
the
DC
voltage
of pin
(20).
The
chroma
signal
input
to
pin
(15)
of
IC200
passes
through
the
chroma
amplifier,
the
saturation
control,
the
contrast
control,
and
the
output
amplifier
circuit,
and
it
IS output
to
pin
(12).
The
chroma
signal
output
to
pin
(11),(12)
is
input
to
the
lH
delay
line
clrcult,
and
is
divided
into
R-Y
and
B-Y
chroma
signals,
and
are
input
to
pin
(11)
respectively.
The
R-Y
chroma
signal
input
to
pin
(11)
is
detected
by
the
CW signal
which
has
a phase
inversion
of 180°
every
lH
at
the
PAL
switching
circuit,
and
is
then
taken
out
to
the
R-matrix
circuit
as
R-Y
demodulated
output.
The
B-Y
chroma
signal
is
detected
by
the
CW signal
which
has
no
phase
Inversion,
and
is
then
taken
out
to
B-matrix
circuit
as
B-Y
demodulated
output.
The
R-Y
and
B-Y
demodulated
output
are
matrixed
G-Y
matrix
circuit,
and
G-Y
demodulated
output
taken
out
to G-matrix
circuit.
The
each
R.G. B.
matrix
circuits
are
mixed
the
luminance
signal
and
each
R-Y,
G-Y
and
B-Y
demodulated
output
signal
to
obtain
the
red,
green
and
blue
primary
colour
eignals,
and
is
applied
the
each
R.G.B.
amplifier
circuits
in
the
IC270.
The
signal
passes
through
the
R,G. B.
amplifier
circuit
are
added
to
the
blanking
pulse
which
is
producted
by
the
sandcast
signal
input
to
pin
(10),
and
output
to
pin
(1)
as
red
signal,
to
pin
(3)
as
green
signal,
to
pin
(5)
as
blue
signal.
The
reference
osci I Iator
operates
at
twice
the
subcarrier
frequency
which
phase
and
frequency
are
controlled
by
the
burst
phase
and
the
frequency
of
the
chroma
signal,
The
oscillator
can
be
adjusted
by
the
voltage
of the
phase
detector
output.
–3–
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