Toshiba CF35E50, Technical Training Manual

Page: 70 / 139

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1. OUTLINE
The H deflection circuit works to deflect a beam from left to
right by flowing a sawtooth waveform of 15.734 kHz into the
DY H deflection coil.
2. HORIZONTAL DRIVE CIRCUIT
The H drive circuit works to start the H output circuit by
applying HVCC (Q501 DEF power source) to pin 22 of
Q501 (TA1222N) and a bias to the H drive transistor Q402
at the main power on.
2-1. Theory of Operation
(1) When the power switch is on, the main power supply of
125V starts to rise. At the same time, AF power supply
25V also rises.
(2) With 25V line risen, Q430 base voltage which is created
by dividing the audio power with R433 and D430 also
rises. Then, the transistor Q430 turns on and the HVCC
is applied from the audio power line through R432 and
D431 to pin 22 of Q501.
Fig. 11-1 H drive circuit block diagram
81 81 22
R432 Q430 D431
R433
D430
BB80
BB81
L400
SIGNAL
C431 C430 D490
H Vcc
Q501