Service manual

CA-14
CA CIRCUIT DESCRIPTIONS
the PIPB1 connector provide sync to the PiP processor. Pins 9 and 10 of the same connector allow I
2
C
bus communication between the PiP board and the microprocessor. PiP brightness however is controlled
from pin 11 of the microprocessor. This controls the bias of Q2210, which varies a DC level on the OSD
input lines to ICX2200.
CR2201C2202M
R2269M
C2242M
C2203
C2204
C2205
D2210
D2211
D2212
C2207
C2206M
R2210
+9VSW
R2771
PROV
C2239
R2268M
Q2210
+9VSW
R2267M
PiP Brt
W2204
W2203
J2202M
J2201M
1 2 3 4 5 6 7 8 9 10
R2202M
C2240
R2201M
R2205M
R2203M
R2207M
R2204M R2206M R2208M
PiP+SW
FASTBLANK
G+UP
B+UP
R+UP
1 2 3 4 5 6 7 8 9 10
+9VSW +5VTuner
FLYBACK
VRAMP
SCL
SDA
R2213M
R2218M
R2222M
R2256M
D2207
R2257M
D2208
R2258M
D2209
R2255
Q2207
C2240M
PROV
HALFTONE
Q2201
Q2202
Q2203
R2209MR2215MR2219M
1
2
3
4
5
R2221MR2217MR2211M
C2238M
12 45
44
43
42
41
40
39
38
37
3621
13
14
15
16
17
18
19
20
CIN
AFT
YIN
DC
VSW-OUT
BLK/DET
VIN
ACL
TV-IN
ABL
VCXO
GND
FBLNK
ROSD
GOSD
BOSD
D-VCC
ROUT
GOUT
BOUT
ICX2200
PIPA1
PIPB1
2C5
<<Figure CA-12>>
After PiP or OSD RGB enters the Jungle IC, it is combined with processed luma and chroma and then exits
ICX2200 as main video for the picture tube. Red, Green, and Blue outputs are found on pins 19, 20, and
21. Some CA receivers have a halftone circuit that taps off these lines. When Q2207 is switched on by a
signal from the microprocessor, a limited amount of RGB signal is shunted to ground. The on-screen effect
of this is a slightly dimmed video. This halftone signal is output in such a way to appear as a darkened but
transparent window surrounding the OSD.
Video Amplification
Before being fed into the CRT socket board via connector 2C5, RGB is pre-driven by Q2201, Q2202,
and Q2203. The resulting signals are then sent to the main color driver transistors, Q5101, Q5102, and
Q5103. These transistors have a high 300V collector to emitter breakdown voltage and a low collector to
base feedback capacitance (less than 3pF). Additionally, the series-parallel arrangement of both their
emitter and base circuits involving both capacitors and resistors allow for improved high and low frequency
response. The cutoff frequency of these drivers is 70 MHz. R5103, 5110, and 5119 from base to collector
help to increase bandwidth response of the drivers. These provide negative feedback from the output and
decrease gain. As gain decreases however, bandwidth response increases. The driver transistors are