1- 7
1.3.2 Cut-off control circuit
IC211
Pre-Amp
IC210
MAIN-Amp
CRT
29
27
25
11
9
8
G
B
R
3
1
5
GK
RK
BK
21
19
20
55
R
255B
R
255G
R
255R
R
254R
R
254G
R
254B
R
256B
R
256G
R
256R
IC102
MPU
D250G D250B D250R
R250G R250R
R250B
215V LINE
G
B
R
G.
BI
A
S
B.BIA
S
R.BIA
S
BRIGHT
D251R
D251B
D251G
3
1
2
IC213
Q251G
Q251B
Q251R
12V LINE
Q250G
Q250B
Q250R
R
2
51G
R
251B
R
251R
R
2
52G
R
252B
R
252R
R
253R
R
253B
R2
5
3
G
D
2
64
R
261
R
260
C250G
C250B
C250R
Fig. 5 Cut-off control circuit
The cut-off control circuit consists of Q250R, Q250G, Q250B, Q251R, Q251G, and Q251B, and
simultaneously adjusts 3 colors (brightness), or individually adjusts 3 colors (biases of R, G, and B). The
microcomputer controls both types of adjustment.
1.3.2.1 Control of brightness
To simultaneously adjust 3 colors (brightness), the DAC voltage (0 to 5V, variable) line of microcomputer
pin 55 is connected to the emitters of Q250R, Q250G, and Q250B via IC213. This connection enables
simultaneous control of three TR collector currents and adjustment of the brightness.
1.3.2.2 Control of BIAS
To individually adjust 3 colors (biases of R, G, and B), the DAC output (1.5 to 5.5V, variable) lines (pins 19,
20, and 21 of IC211) are respectively connected to the emitters of Q250R, Q250G, and Q250B via I2C
bus of the microcomputer. This connection enables respective control of three TR collector currents and
adjustment of biases of the R, G, and B.
1.3.3 OSM (On Screen Manager)
IC212 is the OSM (On-Screen Manager), and displays the screens for screen adjustment, etc. The data to
be displayed on the OSM screens is sent to the MPU (IC102) via I2C bus.
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 ...