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3. EVF CIRCUIT OPERATION
3-1 . SYNC SEPARATOR (SYNC SEPA)
This extracts the sync component from the signal input to
Pin @ of IC971 (BA71 49F}, and then sends this signal
through two separate branches to the phase comparator
(PHAS E COM P) and to the vertical sync separator 0/.
SYNC SEPA).
3-2. PHASE COMPARATOR (PHASE COMP)
This compares the voltage obtained by converting the
horizontal oscillation waveform into a DC voltage at the
low-pass filter (LPF) which is externally attached to Pin ®
with the reference voltage during the sync signal period,
and controls the horizontal oscillation frequency so that the
input signal frequency becomes equal to that of the sync
signal.
The voltage at Pin ® is affected by changes in input signal
frequency (horizontal) .
3-3. HORIZONTAL OSCILLATOR (H. OSC)
The free - oscillation frequency of this horizontal oscillator
circuit depends on the resistor which is externally attached
to Pin ®· A pulse switched by the rise and fall of the
sawtooth waveform from this oscillator is generated and
@
then supplied to Pin
as horizontal output and to the video
amplifier as a horizontal blanking pulse.
3-4. VERTICAL SYNC SEPARATOR
(V. SYNC SEPA)
This circuit separates the sync signal, and then extracts the
vertical sync component from it.
3-5. VERTICAL OSCILLATOR (V. OSC)
The free-oscillation frequency of this vertical oscillator
depends on the resistor at Pin ® and the capacitor at Pin
3-6. VERTICAL DRIVE CIRCUIT (V. DRIVE)
This circuit, which is provided with a built-in operation
amplifier, drives the vertical deflecting coil. An inverted
sawtooth waveform voltage is generated from Pins ® and
@ . Pin CD is a feedback input used to control the sawtooth
wave peak voltage value.
3-7. HORIZONTAL DRIVE
(H.DRIVE
This circuit applies an amplifying current (H. DRIVE) to the
horizontal blanking pulse from Pin @ , then sends it to the
horizontal output transistor. The horizontal deflecting coil
(H. DY) and the FBT primary winding parallel inductance are
made to resonate with the resonance capacitor, and then
the first pulse is extracted to generate the FBT input pulse
voltage.
At the same time, a sawtooth waveform current which is
synchronised to the H .DY horizontal period is generated
from the DC voltage charged by the capacitor which is
connected in series with H . DY and the switching operation
of the horizontal output transistor.
3-8. HIGH VOLTAGE GENERATING CIRCUIT
The pulse voltage produced by resonance during the
feedback period (see previous paragraph) is boosted by a
flyback transformer to generate the CRT g rid voltage. The
CRT anode voltage has a maximum value of approx. 2.2
kV.
(J) .
- 4-24 -
&
&
DEFLECTION
DEFLECTION)
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