Sony KP 48S70, Training Manual

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7
KP-53V80 Video Switching
Overview
In this section we will look at the input-switching path for the KP-53V80.
This includes switching of composite, S video and component video in-
puts.
KP-53V80 Video 4 and Video 5 Inputs
The Video 4 and Video 5 inputs accept component video only. The Y
inputs from Video 4 and 5 are routed to IC1702 A/V Switch. The U and V
inputs are sent to IC1703 and IC1704. These ICs switch the U and V to
either the Main or Sub UV paths. You should note here that the Pb input
is called U in the rest of circuitry and that the Pr input is called V.
Composite Video and Y Switching
Composite video can be input to IC1702 A/V Switch from either THE tuner
or video 1,2 or 3 inputs. The selected composite video input is output at
IC1702/53. This signal then passes through Q1727 Buffer to J1706 Monitor
Out and back into IC1702 at pin 49. When one of the composite video
inputs is chosen, it will be switched to IC1702/56. The composite video
signal is then sent to Q1724 buffer and finally to CN1701/18 which con-
nects to CN401 on the A board. When one of the S video or component
video inputs is selected, the Y signal from the selected input is switched
to IC1702/56. In this case, a Y signal will be output from Q1724 Buffer to
CN1701/18.
Color Switching
Composite video signals are processed by the Comb Filter on the A board.
The Comb Filter separates the Y and C components of the composite
video signal. The C output from the comb filter is coupled through CN1703/
5 to IC1702/51. When a composite input is selected, the Comb C signal
will be switched to IC1702/58. The output from IC1702/58 is passed
through Q1723 Buffer to CN1701 and the A board. When an S video
input is selected, the selected signal is output at IC1702/58. The C signal
passes through Q1723 Buffer to CN1701/16.
If Video 4 or Video 5 is selected the Pb and Pr inputs are routed to IC1703
and IC1704. The Y component input is switched using IC1702 A/V Switch.
The Pb and Pr inputs go to four switches contained in IC1703 and IC1704.
The logic level at CN2001/20 SUV SW and CN1701 MUV SW controls
these switches. These two lines control which signal is sent to the main
or sub UV circuits.
U BOARD
IC1702
A/V SWITCH
CXA 1845
15
14
16
21
22
PB
PR
L
R
Y
PB
PR
L
R
Y
J1703
J1704
TO IC1704
YUV SWITCH
Y4
L4
R4
Y5
L5
R5
KP53V80 VIDEO 4 AND 5 INPUTS
VIDEO 4
IN
VIDEO 5
IN
AUDIO
AUDIO
20