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Circuit Descriptions, List of Abbreviations, and IC Data Sheets
doubler circuit on the SSB, called the Feature Box, changes the
interlaced 625 or 525 signal to a Progressive Scan 480p, 576p,
100Hz, or 120 Hz signal. This YUV signal is buffered and fed to
the SSM where it is buffered before being fed to the HOP (High
end Output Processor) panel. The HOP panel has the HD input
jacks and DB15 RGB input. These inputs can be either 480p,
576p, or 1080i. The Video processing circuits on this panel
perform the Colour, Tint, Brightness, and Contrast adjustments
for the video. Signal selections between the signal from the
SSB and the HD inputs are performed on the HOP panel. Sync
processing and selection is also performed on the HOP panel.
Red, Green, and Blue drive from the HOP panel is fed to the
three CRT panels.
There are two sets of connectors, labelled YPbPr. The one on
the SSM is for NTSC signal levels only. The one on the HOP is
for 1080i, 576p, or 480p Progressive Scan only.
1fH Horizontal (Line) and Vertical (Frame) drive from the SSB
is fed to the HOP via the SSM. The HOP panel selects between
the sync from the SSB or the external HD inputs. These signals
are processed on the HOP before being sent to the LSB.
9.3.1
Side Jack Panel
Figure 9-8 Side Jack circuit
The Side Jack panel has a composite Video and SVHS input.
When there is a connector in the SVHS input, the composite
input is muted. Resistors 3001, 3002, and 3000 on the Video,
Y, and C lines provide 75-ohm impedance matching. If a cable
is plugged into the SVHS connector, the line connecting
resistor, 3029, to ground is removed causing the voltage on the
Y/C_CVBS_SENSE_FRNT line to increase. This signals the
microprocessor to switch the video switching circuits from
composite video to YC In.
There is also a left and right channel audio input.
9.3.2
9.3.3
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SSM Composite Inputs
Figure 9-9 CVBS (composite) video inputs
The composite inputs are located on the SSM. There are two
composite or SVHS inputs. A connector in the SVHS inputs will
mute the composite inputs when the cable in plugged into the
SVHS input. A connector in the SVHS inputs will cause a
voltage change on the SEL-SVHS-RR_STATUS2 line. This will
signal the microprocessor that something is connected to that
input.
SSM Video Switching
Figure 9-10 Video switching on SSM
IC 7017, located on the SSM, performs the Video and Audio
switching for the composite inputs to the SSM. Selected Y or
composite video is output on pin 1 before being fed to the SSB.
Selected C is output on pin 3 and is fed to the SSB. Selected
composite Video for the PIP window is output on pin 39 and fed
to the PIP panel. If an SVHS source is selected for the PIP
window, the YC is combined in 7017 and output on pin 39. IC
7017 is controlled by the microprocessor via the I2C SDA and
SCL lines on pins 33 and 32.
9.
EN 83
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