Sony BVW-55 Maintenance Manual page 123

(3) RF Signal Processing System
(MD-122, RP-107, DM-121, Drum)
Recording system
The external video signals sent from the SDI-23 board are
input to the MD-122 board, and demultiplexed with the Y,
R-Y, and B-Y signals. The Y signal is directly D/A
converted. The R-Y and B-Y signals are time-compressed
by the CTDM IC, and D/A converted as the C signal.
This Y and C (CTDM) signals are added with the sync
signal, setup, CF ID, etc., modulated to the RF signals at
the modulators, and sent to the RP-107 board.
The Y RF signal and C RF signal input to the RP-107
board are passed through the REC amplifier, and sent to
the drum.
At this time, the AFM RF signals sent from the AFM-16
board are superimposed with the C RF signals.
The RF signals passed through the rotary transformer in
the drum are recorded on the tape by the recording heads.
Playback system
The playback outputs of each head are amplified by the
preamplifier in the drum, and input to the RP-107 board
via the rotary transformer. The RF signal inputs are
switched by the switching pulses and head select signals,
and sent to the DM-121 board. However, the C RF signal
is also sent to the AFM-16 board because it contains the
AFM RF signal.
The RF signals (Y and C) sent to the DM-121 board are
each phase equalized and amplitude equalized, and A/D
converted after FM de-modulation. They are then time
compensated by the line memory.
The Y and C (R-Y/B-Y) signal data read from the line
memory is dropout-compensated by the DOC block and
noise-reduced by the ENR block. Moreover, the R-Y/B-Y
signal data is LCC (line crawl cancel-processed) and sent
to the MPX block.
The Y, R-Y, and B-Y signals input to the MPX block are
converted to the D1 format. The converted signals are then
passed through the setup remove block and sent to the
VPR-59 board as playback video signals.
In the setup remove block, the setup is removed for only
the NTSC system (525/60 mode).
BVW-55
(4) System Control Block and Servo Block
(SY-272, SV-206)
This unit mounts a SYS CPU for system control and a
SERVO CPU for servo control.
The RISC CPU is used for the SYS CPU (IC108/SY-272).
The operation clock is 20 MHz.
The SYS CPU controls the operations below.
. Control of switches and LEDs on the control panel.
. Receives and transmits signals with the external
control equipment
. Sub-LCD display
. Superimposing of characters on the monitor output and
LCD monitor.
. Control of main boards
. Self-diagnosis of main boards
. LTC signal read and write
A 16-bit CPU is used for the SERVO CPU, and the
operation clock is 10 MHz.
The SERVO CPU controls the operations below.
. Control of drum and motors
. Detection of sensors and FG/PG
The communication between the SYS CPU and the
SERVO CPU are performed via the DUAL PORT RAM
(IC300).
(5) Power Supply Block (RE-174, PSW-63)
The +12V DC voltage input from the battery or DC IN
connector is sent to the RE-174 board. The voltage is then
turned on and off using the power switch on the PSW-63
board and sent to each board as an UNREG +12V. More-
over, various DC voltage are generated using the DC-DC
converter based on the synchronous PWM switching
regulator and supplied to each board.
6-3