Model Video Path Block; Switching; Main Processing; P&P Processing - Sony KP-43T70 Training Manual

V Model Video Path Block
Overview
The video path in the V model RA-3 chassis is different from that of the
RA-2 chassis because of the addition of two component video inputs.

Switching

There are three types of inputs in the back of the set. They are compos-
ite, S video and component video. The composite signal is input to the
switching circuit and switched to the comb filter. After Y and C separation
the Comb C signal is sent back to the switching circuit. Since a composite
signal was input, this Comb C signal will be switched out and become
Main C. The Y signal out of the comb filter is input to a switch and, when
selected, becomes Main Y.
If an S video input is used, the Y signal will follow the same path as the
composite video but will go around the comb filter. It would be selected at
the Y switch for output instead of the Y from the comb filter. The C signal
would be switched directly from the S video input to the Main C path.
If a component input is chosen, the Y input would follow the same path as
the S video Y signal. A separate circuit that outputs these signals directly
to the YUV Switch switches the U and V signals.
The switching circuit also delivers any of the inputs to the Sub Video path.
This means that SY, SC and SYUV signals are delivered to the sub video
path.

Main Processing

Two separate sources are used for the main video path. They are Main Y
and C (if composite/S video) and component video. Main Y or C is ap-
plied directly to the YCJ. These inputs will be used if a composite/S video
source is selected. If a component video input is chosen then the Main
YUV signals are chosen by the YUV controller and input the YCJ. Keep in
mind that this line will also carry the P&P picture.
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P&P Processing
The P&P processing circuit uses inputs from both the main picture path
and the sub picture path because of the Twin View functions.
The main video path can be from two sources. They are Main Y and C (if
composite/S video is used) and component video. If composite/S video
input is selected for main picture input to P&P, the Main Decoder first
decodes it to YUV. These signals will be selected by the YUV Switch and
input to the P&P Controller. If component video input is chosen, the Y
signal is applied to the YUV switch along with the UV signals from the UV
Switch. These signals will then be selected by the YUV Switch and input
to the P&P Controller.
The Sub video path also comes from two sources. The sub video path
contains a decoding and switching network similar to the one found in the
main picture path. This decoding and switching network will switch the
YUV from the selected source to the P&P Controller.
The P&P Controller outputs compressed YUV signals for its functions. It
also outputs a YUV Switch signal (not shown) that will determine the win-
dow size and position. These signals are sent to the YUV Controller,
which will select either the P&P signal or the component input signal for
output to the YCJ.

OSD

On-Screen Displays are generated by three different sources in the RA-3
chassis. They are System Control, V Chip/CC and PJ OSD and they
share a common input to the YCJ. These circuits have a mute control
system that keeps them from interfering with each other.

YCJ

The YCJ takes the inputs from the Main Y and C paths, the component or
P&P from YUV Controller and the OSD RGB inputs. It processes these
signals and converts them all to RGB drive signals that are output to the
three tubes.