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The 3-beam electron gun is arranged in line, so section of three electron beams is arranged
in line horizontally.
Three electron beams emitted from the electron gun are deflected to scan whole fluorescent
screen.
Electron beam is blocked off by the shadow mask and hits fluorescent material
only corresponding to each color when it passes through the hole.
A set of dots emits light of red, green and blue depending on color signal intensity to
reproduce every possible color.
6.4.3
Main board (AVB401)
The main board is composed of the following:
① Power supply circuit
② Horizontal deflection and high voltage circuit
③ Vertical deflection circuit
6.4.3.1 Power supply circuit
(1) Main circuit
Input voltage is supplied via the filter and rush current limit circuit. This is rectified
and smoothed by the rectifier diode (D100) and input capacitor (C103) to obtain DC
coarse rectified voltage.
transformer (T100) to produce each voltage of P120 (+120V), P70 (+70V), P24 (+24V),
P12 (+12V), HEATER (+6.3V) and P5 (+5V).
(2) Control circuit
P120 output voltage is compared with the reference voltage by the detector circuit.
Signal from the detector circuit is fed back to the control circuit via the photo-coupler
(PC100).
The control circuit controls ON time of the main transistor (Q101) to generate
appropriate drive pulse to stabilize the output P120.
controlled so as to synchronize with the horizontal deflection signal.
(3) Overvoltage and overcurrent protection
In case of overvoltage and overcurrent, this protection circuit keeps the state by IC800
when switching of Q101 stops.
more and turn ON again.
(4) +B power circuit
The +B power circuit controls +B voltage including SPCC and horizontal size
adjustment function.
PC timing) and stabilized by the control circuit (IC106) and switching of the transistor
(Q122).
Switching frequency is controlled so as to synchronize with horizontal
deflection signal.
6.4.3.2 Horizontal deflection and high voltage circuits
In the horizontal and high voltage drive circuit, horizontal AFC circuit IC110 and drive
transistor Q119 drive the deflection coil to flow the horizontal deflection current, and also
drive the flyback transformer (FBT) to supply high voltage of about 24kV to the anode of
CRT.
This is switched by the main transistor (Q101) and
To restart it, turn OFF the power for 30 seconds or
Output is adjusted by VR101 (for TV timing) and VR102 (for
6 - 6
Switching frequency is
L1E-EA0229
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