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Video Path Block
Inputs
The two tuner video outputs along with all video signals that enter the
unit, except the Video 5 component input, are input into IC515 A/V Switch.
IC515 A/V Switch switches these video signals to three different paths.
The first is the main video path, next is the sub video path and last is the
select output. The select output is used to send a composite version of
an input to an output jack on the rear panel. This is selectable in the setup
menu. The default setting is to output the main video.
Main Video
The main video path is used to carry composite or Y/C (S Video) to IC1306,
the 3D Comb Filter. If a composite signal is used, it is looped out of and
back into IC515 A/V Switch, then back out to IC1306 3D Comb Filter. If
an S Video input is used, then the Y signal is looped out and then back
into IC515 A/V Switch along the same path as the composite input. It
then goes to IC1306, 3D Comb Filter. The C signal is output from IC515
A/V Switch to IC1306, 3D Comb Filter.
IC1306 3D Comb Filter is used to separate Y and C signals from the
composite signal input, and also performs some of the necessary noise
reduction and video processing adjustments. If a Y/C signal is input, then
IC1306 3D Comb Filter will just perform its noise reduction and video
processing functions. The C signal is output to IC1305 Main Chroma
Decoder. The Y signal is output to IC1307 YUV Switch where it is switched
though to IC1305 Main Chroma Decoder.
IC1305 Main Chroma Decoder takes the Y and C input signals and con-
verts these signals to component video. Component video consists of Y,
B-Y and R-Y. These signals are also known as Y, U and V and Y, Pb and
Pr. In this book we will refer to these signals as Y, U and V. These main
Y, U and V signals are then input to IC1307 YUV Switch.
IC1307 YUV Switch switches between the main YUV signals and the YUV
signal from Video 5 component input. It also mixes in the Closed Caption
Data from IC1008 Main CPU. The CCD signal is input as a RGB signal
and matrixed to be output as part of the main YUV signal.
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The outputs from IC1307 YUV Switch are then input to the BR board
(DRC) and the BM board (MID). The BR board outputs signals that are
the main video signal and these outputs are input to IC511 Video Proces-
sor. The BM board is used for PIP and Twin View functions.
Sub-Video
The sub-video path is used to carry sub-video to the BM board where it is
converted for PIP and Twin-View functions. If a composite signal is input
to IC515 A/V Switch, it would be output to CM501 Glass Comb Filter and
then input back to IC515 A/V Switch as Y and C. If the signal were an S
Video input, it would pass directly to the Y and C outputs of IC515 A/V
Switch.
The C signal is input to IC1301 Sub Chroma Decoder while the Y signal is
input to IC1302 Sub YUV Switch and then switched to IC1301 Sub Chroma
Decoder.
IC1301 Sub Chroma Decoder takes the Y and C input signals and con-
verts these signals to component video. These sub Y, U and V signals
are then input to IC1302 Sub YUV Switch.
IC1302 Sub YUV Switch is used to select between the sub YUV inputs
and the YUV input from the Video 5 component input. It also mixes in the
Sub-video OSD, which comes from the BM board, into the sub YUV sig-
nal. The output of IC1302 Sub YUV Switch is output as YUV into the BM
board for use with PIP and Twin View functions. The signals from the BM
board are input to IC511 Video Processor.
IC511 Video Processor
The IC511 Video Processor is used to switch or mix in the appropriate
signals among its many functions. These signals are the main YUV, sub
YUV, OSD RGB and PJED OSD RGB signals. These signals are con-
verted to R, G and B to be output to the video amplifiers on each of the C
boards.
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Troubleshooting
