1- 1
1. Circuit description
1. 1 Power block
1.1.1 Outline
The power block is compatible with the business electric power, 100 to 120VAC/220 to 240VAC (50/60Hz).
The active filter circuit is adopted to suppress the higher harmonic current.
The circuit block is composed of two switching regulators, the main power which is the configuration used
the flyback converter system of pseudo resonance operation and the sub power which is the configuration
used PWM (pulse wise modulation) system.
The output on the secondary side is shown in Table 1.
Table 1
1.1.2 Rectifying circuit and higher harmonics suppression (active filter) circuit
The AC input voltage is rectified in the full wave mode with the diode bridge in D901 and input to pin 5 of
L903. The voltage of both end of C911 is the DC voltage approx. 390VDC boosted with the booster
circuit (active filter circuit) composed of IC901, Q901, L903 and D902. The active filter circuit compares
the voltage input to pin 1, pin 3 and pin 4 of IC901 and controls Q901 ON/OFF period so that the current
flows to L903 be sine-waved. The AC input current is sine-waved in the same phase with the input
voltage so as to improve the power factor, and the harmonic current is controlled consequently.
Fig. 1
Power block
Output voltage
Mai load
+215V
H. deflection circuit, Cu-off circuit
+80V
Video circuit, DBF circuit, High voltage circuit
+15V
H. deflection circuit, Rotation circuit
-15V
Convergence circuit, Corner purity circuit
+12V
Video circuit, H. deflection circuit
Main power side
+8V Heater
+5V Microcomputer
(MPU)
Sub power side
P-OFF+5V VIDEO
circuit
R904
②
①
③
④
⑤
⑥
⑦
⑧
⑨
⑩
⑪
⑫
⑤
⑦
①
④
②
⑥
⑧
③
IC901
D901
L902
C906
R905
R906
R908
C907
C908
C910
R911
R912
Q901
L905
L903
D933
D902
C911
+
R913
R914
R915
R917
R907
To Main power
and sub power
From Sub power
Vcc
AC
AC
R909
R910
R937
Summary of Contents for DPro2070SB
Page 22: ...1 15 Fig 7 The principle of DDCC compensation ...
Page 23: ...1 16 Fig 8 a DDCC adjustment item ...
Page 24: ...1 17 Fig 8 b DDCC adjustment item ...
Page 25: ...1 18 Fig 9 DDCC circuit diagram ...
Page 103: ...4 Wave form 1 POWER 2 CONTROL MAIN 3 DEFL MAIN 4 DEFL SUB COIL DRIVE MAIN 5 VIDEO ...