Board - Sony CCU-TX7 Service Manual

3-3. CIRCUIT DESCRIPTION
CT-181 board
CT-181 board employs RF system circuit that is consists of
RETURN VIDEO modulation circuit and PROMPT VIDEO
modulation circuit (It becomes AUX VIDEO demodulation
circuit by switching.) and microcomputer system circuit that
controls the system.
Microcomputer system circuit section :
The program is written in the ROM (IC1022) that is inserted
to socket (CNI 1). ROM of built-in microcomputer is not
used. Input and output of control signals between each board
in CCU (included in COU) and each board are performed by
serial data of 16 bit via I/O EXPANDER (IC1028). There are
four communication channels with outside. The SCI-1 and
SCI-2 built-in microcomputer communicate with CA (via
modulation and demodulation circuit ) and RCP (via RS-232C
driver). The external SCI (IC1024 and 1025) communicates
with command link (RS-232C-1 and RS-232C-2 on the rear
panel).
The RF system circuit section :
RETURN VIDEO modulation circuit frequency-modulates
the input signal (VBS) from RETURN VIDEO 1 or 2, and
sends to the CA. Change of RETURN VIDEO 1 or 2 is
switched by RETURN 1 and 2 changing switch on the CA.
The PROMPT VIDEO modulation circuit amplitude-
modulates the input signal (VBS) from PROMPT VIDEO on
the rear panel, and sends to the CA. The PROMPT VIDEO
modulation circuit becomes AUX VIDEO demodulation
circuit by switching S2002 and connecting RF coaxial cable to
CN3 and CN8. (It is needed to change on the YD-25 board of
CA.)
Demodulated AUX VIDEO is outputted from PROMPT
VIDEO on the rear panel.
AA-90 board
This board demodulates the RF signal of MIC1, MIC2,
INCOM, CAM DATA and TONE sent from the CA,
modulates a PGM signal, the INCOM signal and control data
send to the CA. And also, this board switches the INCOM
line, and switches the input /output of each audio signals.
3-4
YD-26 board
YD-26 board demodulates Y, R-Y, B-Y, CAM SYNC and
SKIN GATE. This circuit consists of cable length detection
circuit, cable length compensation circuit and these
demodulation circuits. The cable length detection detects
from amplitude of Y modulated wave. In accordance with
this, the cable compensation circuit compensates the
amplitude and phase matching as cable length to modulated
wave of Y or differential signal. After that, they are
respectively demodulated in demodulator circuit.
ES-20 board
This board produces VBS and RGB signal from the Y, R-Y,
and B-Y signals sent from the YD-26 board, switches these
signals, and outputs them as WF and PIX signals. This
board also generates each sync signal and color bars signal.
AU-234 board
This board inputs and outputs an INCOM signal on the front
panel, displays tally signals, and turns on and off the power
of camera.
IO-140 board
This board mixes the RF signal between CA and CCU with
the power of the camera.
SDI-44 board (DXBK-701)
This board converts the analog video/audio signals into
digital signals and outputs them as SDI signals.
Video signal processing :
Y, R-Y and B-Y signals sent from the ES-20 board are
converted from analog to digital and subject to the double
over-sampling process on the digital filter IC308.
Audio signal processing :
MIC1 and MIC2 signals sent from the AA-90 board are
converted from analog to digital and subject to 64 times
over-sampling process on IC904 and then subject to time-
base compression on IC404.
These digital video signals and the time-base compressed
digital audio signals are mixed on IC413. After that, the
parallel data is converted to serial data on IC702 and output
from this board.
CCU-TX7(E)/V1