4-4
DNW-7/90/90WS
(6) Power supply system
(CNB-1 board (2/2), RE-118 board, and RE-119
board)
.
CNB-1 board (2/2)
The input DC 12 V from the battery pack or DC IN
connector is input to the CNB-1 board (2/2) where the
input 12 V passes through a breaker and turned on or off
by the POWER switch and is output as an UNREG 12 V.
This output voltage is sent not only to the camera and
VTR blocks but also to the RE-119 board.
.
RE-118 and RE-119 boards
The RE-118 and RE-119 boards make up a DC-DC
converter. The UNREG 12 V supplied from the CNB-1
board (2/2) is converted to the various output DC
voltages which are sent to the camera and VTR.
The converter system uses an highly efficient synchro-
nous type PWM switching regulator system.
The PWM switching regulator is equipped with a short-
circuit protection circuit which turns off all outputs when
any of the output power is shorted to GND. The PWM
switching regulator is also equipped with the cut-off
circuit which shuts down the output power when the
input voltage is decreased below the guaranteed operat-
ing voltage.
(5) Servo control block
(MDC-5 board and HN-224 board (2/2))
.
MDC-5 board
The MDC-5 board has the two MPUs. MPU1 controls
the mode control and capstan servo system while
communicating with the system control CPU in serial
communication. MPU2 controls the drum servo system
while interfacing with MPU1.
The drum motor and capstan motor are controlled by the
PWM switching drive of the feedback servo between FG
and PG pulses and between FG and CTL pulses, respec-
tively. The threading motor is controlled by a bidirec-
tional motor driver.
