Sony BVP-500, Maintenance Manual

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2-4
BVP-500
BVP-500P
•
VF OUT signal
Switching between the return video or reference signal
which is selected with S200/IF-538 board, and the VF-Y
singal is done by the
CAM
/RET signal. The selected
signal is via a lowpass filter to the PinP (Picture in
Picture) circuit to be processed as a small picture signal.
At the next stage, an analog switch switches back and
forth between the large and small picture signals to
display the small picture in the large picture. In combi-
nation with this analog switch and another analog switch
at the front of the PinP circuit, reversing between the
large and small picture signals, and moving the position
of the small picture are allowed by operating the rear
panel switch. At the final stage, thus picture-in-picture
signal has center marker and safety zone pulse signals
mixed on it and is output at the IF-538 board.
•
MONITOR OUT signal
The S650/IF-538 board selects a signal from VF signal,
VBS signal or one of the return video or reference signal
selected with S200/IF-538 board. The selected signal is
output via the amplifier at the MONITOR OUT connec-
tor on the side of the camera. When the VF signal is
selected, however, it is switched over to the VF-Y or
RET signal by the
CAM
/RET signal corresponding the
VF display selection.
In addition, the IF-538 board is equipped with the follow-
ing circuits.
•
HD/VD external sync circuit
When displaying the return video or reference signal on
the viewfinder screen, it is necessary to synchronize the
cursor signal with those signals. And a sync signal is
separated from those signals to generate the external HD
and VD signals, and the resultant is sent to the cursor
signal generation circuit on the PR-211 board.
• Peak-detects the G signal and outputs to the AT-95
board.
• Transmits the SKIN GATE signal from DA-88 board to
the MD-103 board.
2-3. Circuit Description
(3) Auto system
AT-95 board
The AT-95 board consists of a microcomputer which
controls the camera according to the instructions stored in
a ROM. Operations of the board are listed below;
• Analyzes video system detection data, analog data and
instructions of the function switches.
• Outputs various control signals and compensation
signals to the boards.
• Outputs status information and self-diagnosis informa-
tion as character data from the character generator.
• Incorporates the interface function with the RM-P9 or
the CCU-700/700P.
(4) Pulse system
SG-234 board
The SG-234 board has a sync signal generator which
generates various sync signals for the camera. The sync
signals are generated from the clock pulse input from the
OHB via the PR-211 board. They are output to the boards
of the camera and OHB respectively. This generator has
two modes to synchronize with a reference signal input for
external synchronization. One is a VBS input mode when
the camera is used together with the standalone unit BKP-
5910/5910P and the other is a V RESET/H CONT mode
when the CCU is connected to the camera.
(5) Audio modulation/demodulation system
AU-211 board
The CHU/RCP data is input/output from/to the AU-211
board. And audio signal processings such as the audio
mode switching and gain control of MIC CH-1 and CH-2
are performed.
The received data from the RCP goes through the photo-
coupler and is then send as the COM CONT signal to
control the camera, to the AT-95 board. If the CCU is
connected to the unit, the COM CONT signal is automati-
cally send to the CCU. As for how to select the IN-
COM mode, refer to Section 1-5 “Function of Internal
Switches – AU-211 board”. In addition, the AU-211 board
supplies the power to the MIC CH-2 connector.