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Deflection Circuit And High Tension Circuit - Sony TRINITRON PVM-14L5 Service Manual

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5-4. Deflection Circuit and High Tension Circuit

The following circuits consisting the deflection circuit and high-tension circuit, are contained the three
circuit boards of G board, D1 board and D board.
Parts and components in the G board have the parts reference number of 500 series. Parts and compo-
nents in the D1 board have the parts reference number of 1500 series.
Parts and components in the D board have the parts reference number of 2500 series.
1. Sync signal processing circuit
The horizontal and vertical sync signals that are input from CN2504 (pin-4/pin-12) on the D board, are
sent to the D1 board via CN2507. In the D1 board, the horizontal and vertical sync signals pass through
the H/V delay timing circuit consisting of IC1501, IC1503 and IC1507, receive the waveform processing
in IC1504 and IC1508, and then are sent to the deflection signal processor IC1505.
IC1505 generates the various waveforms of the horizontal drive waveform, dynamic focusing parabolic
waveform, picture distortion correction parabolic waveform, vertical drive waveform and H/V blanking
2
waveform. Output of these waveforms is directly controlled by microprocessor via I
C.
The horizontal free running frequencies are adjusted respectively in the modes of 480/60i (15.734 kHz),
480/60p (31.5 kHz), 1080/60i (33.75 kHz) and 720/60p (45.0 kHz). The horizontal free running frequen-
cy in the case when there is no video input signal, is the frequency that is locked immediately before the
input video signal disappears. If there is not video input signal when the main power is turned on, the
horizontal free running frequency is 15 kHz.
2. PWM control circuit generating the + + + + + B power voltages for the deflection circuit and
high-tension circuit
The PWM control circuit generating the +B power voltage, consists of IC1509 and the peripheral circuit.
The deflection distortion correction signal that is output from IC1505 pin-8 is compared with the feed-
back voltage from the horizontal output circuit. The comparator output is used as the PWM control signal
for horizontal deflection. The PWM control signal is output from IC1509 pin-11. This PWM control
signal is sent to the +B power regulator circuit consisting of Q2504 and the peripheral circuit where the
H size and deflection distortion are controlled.
The reference voltage that is generated by IC1510 is input pin-16 and is compared with the high-tension
voltage detector output of FBT that is input to pin-17. The comparator output is used as the PWM control
signal for high-tension voltage. The PWM control signal is output from IC1509 pin-13. This PWM
control signal is sent to Q511 and the peripheral circuit where the high-tension voltage is controlled.
The PWM control signal that is output from IC1509 receives the DTC (dead time control) to prevent the
horizontal drive circuit and the high-tension output circuit in the case of sharp change of input signal
frequency. DTC operates as follows. When the input signal is switched, the unlock signal that is output
from microprocessor is used so that the DTC signal is input to pin-6 via the switches Q1506 and Q1508
that control the PWM signal to decrease the horizontal and high tension +B regulator output voltage
tentatively.
3. Horizontal output circuit
The horizontal drive signal that is output from IC1505, is amplified by the horizontal drive circuit
consisting of Q2505, Q2506, Q2507 and the peripheral circuit, drives T2502 (HDT) and Q2508 (H OUT).
The H pulse that is generated by resonance between C2533, C2553 and the DYH winding coil imped-
ance, is voltage-divided and is shaped of its waveform by IC2504 and the peripheral circuit. The H pulse
is then supplied not only to IC1505 pin-14 as the AFC pulse but also supplied to the B board.
The horizontal deflection current is detected of its amplitude by T2503, Q2537 and the peripheral circuit,
and is fed back to the PWM control circuit.
5-5
PVM-14L5/20L5/D14L5A/D20L5A

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