Deflection Processor Block; Deflection Processor (Ic601); Pressure-Reduction Type Horizontal Deflection Power Circuit (Ic5C0); Horizontal Width Control Circuit - NEC DPro2070SB Service Manual

1.2 Deflection processor block

1.2.1 Deflection processor (IC601)

Deflection processor IC601 horizontally compensates wise, position and distortion, and vertically controls
heights, position and linearity.
IC601 automatically tracks the frequency to output the appropriate horizontal/vertical drive pulse.
IC601 also outputs the horizontal parabola waveform for focus and the waveform for convergence
compensation.

1.2.2 Pressure-reduction type horizontal deflection power circuit (IC5C0)

IC5C0 compares the parabola waveform output from pin 64 of IC601 (this waveform controls the
horizontal width and distortion) with the sawtooth waveform (this waveform is synchronized with the
horizontal frequency) in order to output the +B drive pulse. The +B drive pulse output from pin 9 of IC5C0
will accumulate the 215V energy in T550 during Q5F1 ON period. During Q5F1 OFF period, the
accumulated energy will be released, and integrated by T550 and the S-shaped compensation capacitor.
The duty of this drive pulse depends on the DC level of the parabola waveform that is output from IC601.

1.2.3 Horizontal width control circuit

Q550 is controlled by the horizontal drive pulse that is output from IC601. When Q550 is ON, the energy
will be accumulated in the horizontal deflection yoke. When Q550 is OFF, the energy will flow into C550.
While repeating this operation, horizontal deflection will be carried out.
The collector pulse of Q550 will be subject to voltage division by C590 and C591, and the voltage-divided
pulse will be used for switching synchronization of the high-voltage control IC701 and also used as the
AFC pulse.
The duty of the +B drive pulse output from pin 9 of IC5C0 will be subject to change in order to control the
horizontal width. The parabola waveform output from IC601 is compared with the feedback waveform
output from T5C0 to obtain the comparison waveform, and this comparison waveform threshes the
sawtooth waveform inside IC5C0 in order to control the duty. If the duty is changed, the rectified voltage of
the S-shaped compensation capacitor will be changed, and the horizontal width will be also changed. The
vertical parabola waveform is generated inside IC601, and then mixed with the DC level for horizontal
width control. After that, the mixed parabola waveform will be output from 64 pin of IC601, and added to
IC5C0. This parabola output will be used for compensation of pin-cushion distortion, barrel distortion,
trapezoidal distortion, and upper/lower distortion.

1.2.4 Vertical deflection circuit

1.2.4.1 Sawtooth waveform generation, vertical size/position control, and linearity control circuit

If the vertical synchronization signal is input to 42 pin of IC601, the bipolar sawtooth waveform having the
same frequency as the input will be output from pins 1 and 11 of IC601. IC601 receives compensation
data from the MPU (IC102) to compensate the vertical size, vertical position, vertical raster position,
vertical linearity, and vertical linearity balance, and then outputs the compensated sawtooth waveforms
from pins 1 and 11. Pin 2 outputs the voltage to show the vertical deflection intermediate point.
The OP amplifier at the next stage outputs a signal to show the difference of the bipolar sawtooth
waveform. For this output, the RC low pass filter is adopted to eliminate the digital gradation of the output
waveform. In addition, pins 62 and 63 of IC601 will be turned ON during retracing operation in order to
prevent deterioration of the linearity and dispersion of scanning lines. Moreover, Q603 and Q604 are
switched depending on the vertical frequency in order to improve the linearity.
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