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VERl_l
CAl_
OUTPUT
An
IC
(LA7831)
is
used
for
the
vertical
output
circuit
in
this
chassis.
The
vertical
drive
pulse
from
pin
(1)
of
IC401
is
input
to
pin
(6)
of
IC450.
This
pulse
drives
b
IC450,
and
the
vertical
scanning
is
performed.
In
the
first
half
of
scanning
a
deflecting
current
is
output
from
pln
(4)
and
passes
through
the
following
path:
VCC25V.+
D450+
pin(5)=+
pin(4)+
DY+
C451+
VR405.
An
electric
charge
is
then
stored
in
C451.
In
the
last
half
of scanning
the
current
path
is
C451+
DY+
pin(4)
+
pin(6)+
VR405+
C451.
In
this
way,
an
amplifying
sawtooth
waveform
current
flows
directly
to
DY
to
perform
the
electron
beam
deflection.
Next,
in
the
first
half
of
the
blanking
period
the
vertical
drive
pulse
suddenly
becomes
OFF,
and
in
order
td
reduce
the
current
flowing
to
DY,
the
current
path
becomes
to
follow
by
the
inductance
of
DY:
DY+
pin(4)+
pin(6)+
VR405+
C451+
DY.
Also,
when
the
charge
of
DY
has
dissipated,
the
current
path
becomes
VCC25V+
pin(8)+
pin(9)+
C457Eb
pin(5)=o
pin(4)+
DY+
+
C451*
VR405
and when
the
prescribed
current
value
is
reached
enough,
the
vertical
drive
pulse
becomes
ON.
This
completes
one cycle.
HORIZONTAL
OUl_l=Ul_
A
horizontal
oscillation
signal
is
output
from
pin
(11)
of
IC401
and
switches
the
drive
transistor
Q490.
This
switching
signal
current
is
amplified
by
the
drive
transformer
T490
and
drives
the
output
transistor
Q493.
When
Q493
becomes
ON,
an
amplifying
current
flows
directly
to
DY
through
C476+
L475/R4794
DY~
Q493+
+
GND,
and
deflection
is
performed
in
the
last
half
of
the scanning
period.
Next,
when
Q493
becomes
OFF,
the
charge
that
had
been
stored
in
OY
up
to
that
point
releases
a
resonance
current
to
the
resonant
capacitors
C493
and
C494
and
charges
them.
The
current
stored
in
C493
and
C494
is
then
flowed
back
to
DY,
and
an
opposite
charge
is
then
stored
in
DY.
This
opposite
charge
then
switches
the
dumper
diode
In
Q494
ON,
the
resonance
state
is
completed,
and
an
amplifying
current
is
then
flowed
again
directly
to
DY
through
the
dumper
diode.
By
this
means,
the
deflection
in
the
first
half
of
the
scanning
period
IS
performed,
and
when
Q493
becomes
ON
at
the
w
end
of
the
first
half
of
the
scanning
period,
the
deflection
during
the
last
half
is
begun,
thus
completing
one cycle.
HIGH
VOLTAGE
The
looov~.~
blanking
pulse
is
generated
In the
PrimarY
coil
of
the
flyback
transformer
T480,
and
it
is
boosted
10-
15
times,
and
a stable
high-voltage
pulse
superposed
with
harmonics
nine
times,
and
the
fundamental
harmonics
IS generated.
This
is made
into
a 20-30kV
DC
voltage
by
using
a
double-voltage
rectifier
circuit.
Furthermore,
the
intermediate
voltage
of
the
double-voltage
rectifier
circuit
is
divided
by
the
resistance,
and
used
as
the
focus
and
the
screen
voltages
for
the
CRT.
This
resistance
for
the
potential
division
is
unified
in
the
flyback
transformer.
Moreover,
the
accompanying
coils
are
used
to
generate
the heater
voltage,
and AFf
pulse.
–4–
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