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I2C2
Tuner
ANT Clk Dat
11 10 OSD
IF from SysCon
Dat
I2C2 1/2 Sound/Pix IF IG401
Clk II60
Rear (CV)
Video 17
4 2 15 16 17 To
Video (CV) CRT
6 7
Y Video Video/ 19 R
Input Y-Out Deflection 20
C 5 17 43 Processing G
Switch C-Out 21 B
(CV) Front 10 16 45 IV01
Video IV02
Video (CV) Dat 28
15 18
I2C2
Y-In C-In
Clk 27
CC Video 20 11
to SysCon Chroma Luma
IG401 Buff/Filter Buff/Filter
TV523 TV522/526
TX809 Video Switching/Processing Block Diagram
Video Switching & Processing
The Video Switching and Processing circuitry in the TX809 includes the Video
Input Switch IV02, the Video/Deflection Processing IC IV01, the Sound/Pix IF IC
II60 and the tuner. The video switch IV02, video/deflection IC IV01 processor
and the sound/pix IC II60 are controlled via the System Control IG401. The CC
Video (Closed Caption) is output from pin 15 of switch IV02 and sent to the
system control (IG401) for decoding. Transistors TV522, TV523 and TV526 are
used to separate the composite video signals into separate luma (Y) and chroma
(C) signals. The composite video (CV) from the Sound/Pix IF (II60) and the front
and rear input jacks are first routed through IV02 and output at pin 18. The
composite video is applied to chroma and luma filter circuits for separation. The
separated Y & C are then input back into IV01 at pins 11 and 20. The Y/C (S-
Video) input is routed directly through switch IV02 for final processing. The
selected video is output at pin 16 and 17 and applied to pins 43 and 45 of IV01
for final processing. All brightness, contrast, color and tint adjustments are
performed by the video processor (IV01). The RGB OSD (On-Screen-Display)
from the system control IG401 is also input to the video processor at pins 15, 16
& 17.
Troubleshooting
NOTE: Always use known video source such as color bars. If a video problem
is suspected perform the following:
1. Confirm presence of all power supplies for circuit.
2. Check I2C2 for data & clock activity when a function is selected.
3. Check for video from II60-17 (Sound/Pix IF) during tuner operation.
4. Apply video to front/rear video inputs and check for video at IV01-18.
5. If OK, check for Y & C out of transistors TV522, TV523 & TV526.
6. If OK, check for Y & C at IV02-16/17.
7. Check for correct RGB out of IV01-19/20/21 (Video Processor).