Sony DTV-01, Manual

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33
Video Process B
Signal Flow
Input Selection
Main component video from the Chroma Decoder IC2406 is only one input
into switch IC2406. The second input to IC2406 is DVD component video
from the rear panel phono jacks.
The Main Micro IC3251/pin 78 and 79 sends logic level voltages into IC2406/
pins 25 and 4/27 for the input selection. The chart shows the switching
voltages for selecting an input:
I C 2 4 0 6 S e le c tio n
I n p u t s e le c te d I C 2 4 0 6 /p in 2 5 I C 2 4 0 6 / p in s 4 , 2 7
M a in ( R F , v id e o ) L H
D V D H L
Closed Caption
The luminance passes through switch IC2406, which adds closed caption
or XDS station information as an OSD. If the user requests this feature,
this caption information enters IC2406 as an RGB signal from IC2409.
The take off or input signal for the closed caption decoder IC2409 is at the
output of this YUV switch at IC2406/pin 22.
Filtering
When high frequency analog signals are sent into a digital stage, the high
frequency component can create a secondary signal. This second signal
is called an alias component. Alias signals are eliminated by low pass
filtering (LPF) the analog input. That is the purpose of the filter networks at
the output of IC2406.
DTV Selection
Switch IC2407 chooses between the main and DTV signal for the main
picture path. The DTV signal is chosen only when:
·
Viewing the HD or SD Digital TV signal as a sub picture (Twin View
mode) or
·
The DTV signal is of standard definition (525 lines/480 lines viewable)
and line doubling is required.
The DTV path is chosen when IC2407/pin 9-11 is low:
IC 2 4 0 7 S e le c t io n
In p u t s e le c t e d S w s ig n a l IC 2 4 0 7 /p in 9 , 1 0 , 1 1
M a in ( R F , v id e o ) H
D T V L
The output of the DTV/Main switch IC2407 is buffered and sent through
the G board to the V board for digital processing.