Sony KP 48S70, Training Manual

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31
DTV Video Processing
Overview
This section discusses the video path for the DTV inputs. It is designed to
aid you in troubleshooting by providing you the IC pin numbers that carry
the video signals.
Circuit Description
J501 in the rear of the set has a green input labeled Y/G, a blue input
labeled Pb/B, and a red input labeled Pr/R. These is a dual input connec-
tor which accepts both component and/or RGB input. The user deter-
mines which type of input is expected in the set up menu. If the wrong
type is selected, the color of the picture will be wrong.
Regardless of which type of signals are input, they will be sent to IC511/5,
4 and 3. These signals are processed for correct color and output at
IC511/76 SEL Y Out, IC511/77 SEL CB Out and IC511/78 SEL CR Out.
These signals are split to two ICs. First they are input back into IC511/75
SEL Y IN, IC511/74 SEL CB In and IC511/73 SEL CR In respectively. If
the input signals were 1080I or 480P, they would be converted to RGB
and output to the tubes at IC511/35 R Out, IC511/37 G Out and IC511/39
B Out.
The outputs from IC511/76, 77 and 78 are also input to IC1403 at pins 12,
5 and 2. IC1403 is a switching IC that switches between the YUV, which
came from the Video 5 DTV input, and the inputs from Video 4. These
signals are input at IC1403 pins 3, 1 and 13. The inputs selected are
dependent upon the inputs at IC1403 pins 9, 10 and 11. If the input to
these pins is Low, the DTV inputs are selected and if the inputs are High,
then the Video 4 component inputs are selected. In this case the input
would be Low since we want to select the Video 5 DTV inputs. The DTV
YUV signals are then output from IC1403/4, 15 and 14.
These signals are input to IC1307/7, 6 and 5 for two reasons. Firstly, if
the signals input to Video 5 are 480I format, they need to be switched to
the main video path for DRC processing. Remember the normal picture
on this set is a 960I signal from DRC. Secondly, the Y signal needs to be
switched to IC1307/22. If we continue to follow this path, we can see that
the signal is sent to IC1303 SW. It will be selected anytime a DTV signal
is input, except when the signal is 720P format. It is sent to Main CPU V
In for V Chip/CC for the accepted formats. The switching of IC1303 is
controlled by its input at pin 2. This signal comes from IC1009/61 O
720P. When a 720P signal is input, the switch in IC1303 changes posi-
tion and switches the signal in from the Y/G input. The same control line
also disables the outputs of IC1307 Main YUV Switch.