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8-20
V.DF. output
(1bitDAC)
58
R527
R540
R541
R529
R528
IC510
IC510
C520
3.3V
Aprox. 1Vp-p
Aprox. 3Vp-p
Integration circuit
Inverting amplifier
(3times amplifier)
1V
(Fig. 5.2) The vertical parabolic wave generation and gain control circuit
3) The output amplifier circuit and the coupling circuit
The horizontal and vertical parabola waveforms output from IC501 are clamped before each output
circuit for wide dynamic range of the output circuit. The clamp voltage is determined by the voltages of
ZD951 (for the horizontal parabolic wave) and ZD981 (for the vertical parabolic wave).
After the clamp circuit, the horizontal parabola waveform is amplified approximately 12 times by Q981.
The output signal at Q981 collector is input to T981 via the buffer circuit which is composed of Q982,
Q983, Q984 and Q985. The gain of T981 is approximately 9. The vertical parabola waveform is
amplified approximately 80 times by Q987. The output signal at Q987 collector modulates the secondary
winding of T981 as the vertical parabola waveform. Therefore, T981 outputs the horizontal parabola
waveform which is modulated by the vertical waveform. This modulated waveform is input to the CRT
focus grid via the built-in capacitor of T5R1 (FBT).
D984
C986
R992
R990
C984
ZD981
R993
C985
+220V
R989
R991
To FBT(T5R1)
Q984
T981
C983
R952
Q985
Q983
Q982
R985
R986
R983
R984
C989
D981
D982
Q981
+80V
+15V
+12V
-80V
Q951
R951
R953
D951
C959
ZD951
C958
From IC513
From IC510
(Fig. 5.3) The dynamic focus output circuit