Sony CTV-25R1, Manual

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69
Video Inputs
The Y/C Jungle IC not only performs luminance (Y) and chroma (C) pro-
cessing, but input selection as well. There are as many as seven inputs
the Jungle IC can select from. They are shown in the chart below:
Jungle IC Inputs
Name IC001/
Pins
Switch Access
Tuner 43 Data (IC001/pin 35) C/-,
TV/video buttons
Video 1 2, & 4 Data (IC001/pin 35) TV/video buttons
Video 2 41 Data (IC001/pin 35) TV/video buttons
OSD * 30 – 32 5V positive pulses from
IC001/pin 49 replace
pieces of video with OSD
character pieces.
2Vdc from IC001/pin 41
reduces video brightness
(menu).
Display or Menu
buttons.
Closed
Caption
(CC) 30 - 32 5Vdc from IC001/pin 49
blacks out video to form
the CC text box and allow
CC characters to appear. Select caption
vision from the
Menu. CC does
not appear in
most programs.
Y & C
from the
comb filter 7, 9. Data (IC001/pin 35). Selected when
the ID codes
(service
adjustment mode)
identify the model
with a comb filter.
Picture in
Picture 37 - 39 YUV sw into IC301/pin 36.
Switching pulse:
High – PIP picture
Low – Normal video input
PIP button on the
remote control.
* OSD = On Screen Display of characters (menu or channel numbers)
OSD and Closed Caption
Before the OSD circuit can function within IC001, it needs timing signals.
Horizontal pulses from the horizontal output transistor Q502/collector are
applied to IC001/pin 17. Vertical timing signals from the Jungle IC301
are applied to IC001/pin 2. Both timing signals are necessary to position
the OSD characters on the screen. If one were missing, there would be
no OSD or CC text.
The OSD characters generated from IC001/pins 50-52 are accompanied
by switching signals applied to IC301/pin 29. These switching signals
must go HIGH to displace the input video and enable the OSD R, G and
B that is input IC301/pin 30-32. Inside the Jungle IC, the R G, and B
characters replace pieces of the video.
The level of voltage input to IC301/pin 29 determines if the input video is
blanked or just reduced in brightness. If IC301/pin 29 is brought to 5
volts, the video will be blanked completely permitting the OSD to appear.
If IC301/pin 29 is brought to only 2 volts, the video will appear at reduced
brightness, such as when the menu button is pressed. The full 5-volt
video-blanking signal comes from IC001/pin 49 and the ½ brightness
signal comes from IC001/pin 41 via R092 (10Kohm).
The closed caption stage is within Micro IC001 and only requires three
signals for operation. The H & V sync information that is used by the
OSD stage is also used in the CC circuits for positioning. Video input
IC001/pin 22 to extract the CC information from a line in the vertical inter-
val is the remaining signal necessary for operation.
Additional Signals necessary for the OSD and CC to function
Input Location
OSD Horizontal pulses
Vertical pulses
Q502/collector
IC301/pin 5
CC CC video information
Horizontal pulses
Vertical pulses
Q305/emitter