S Model Video Path Block; Switching; Main Processing; Pip Processing - Sony KP-43T70 Training Manual
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Also See for KP-43T70:
- Service manual (100 pages) ,
- Operating instructions manual (54 pages) ,
- Supplementary manual (1 page)
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S Model Video Path Block
Overview
The video path in the S model RA-3 chassis is different from that of the
RA-2 chassis because of the addition of a component video input.
Switching
There are three types of inputs located at the rear of the set. They are
composite, 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 Y and C signals are sent back to the switching
circuit. Since a composite signal was input, this Comb Y and C will be
switched out and become Main Y and C.
If an S video input is used, the Y and C signal will be switched directly to
the Main Y and C outputs. If a component input were chosen, the compo-
nent Y signal would follow the same path as the S video Y signal, i.e., it
would be switched directly to the Main Y path.
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 or component video. Main Y or C is applied 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 to the YCJ. Keep in mind that these lines
will also carry the PIP picture.
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PIP Processing
The PIP processing circuit uses inputs from only the sub picture path.
The main video path can be from two sources. They are Main Y and C or
component video. If composite/S video input is selected for sub picture
input to PIP, it is first decoded to YUV by the Sub Decoder and applied to
the YUV switch. If a component video input is chosen, the Y signal is
applied to the YUV switch along with the UV signals from the component
inputs. These signals will then be selected by the YUV Switch and input
to the PIP Processor.
The PIP Processor outputs compressed YUV signals. It also outputs a
YUV Switch signal that will determine the window size and position. These
signals are sent to the YUV Controller, which will select either the PIP
signal or the component input signal for output to the YCJ. The PIP Pro-
cessor also outputs M H Sync to the Y Switch. The Y switch selects either
the MY or M H Sync inputs. MY is selected for normal and PIP functions.
M H Sync is selected when the user selects Auto Program or Favorite
Channel function. When this sync signal is switched into the YCJ, it is
placed on a DC level that causes a gray screen to be seen in place of the
main picture.
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
PIP from YUV Controller and the OSD RGB inputs. It processes these
signals and converts them all to RGB drive signals, which are output to
the three tubes.
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