4-2
HDW-250
The system control CPU controls the time code reader and
generator, character generator, front panel key control,
LCD display and signal processing system. It also per-
forms communication with camera and other external
equipment.
The servo control CPU receives the command from the
system control CPU, detects the sensor status, and the FG/
PG status so that it can control the drum and motors.
The unit can be controlled from external equipment
through the Sony 9-pin protocol or ISR.
Power Supply System
DC 12 V is supplied from a battery or through the DC IN
connector. DC 12 V passes through the power supply
selector circuit in the FU-76 board and is input to the DC/
DC converter (PSW-67/68/69/70) board.
DC 12 V is up- and down-converted to the various DC
voltages by the DC/DC converter so that the various DC
voltages are supplied to the respective circuits inside the
unit and to the external camera and others.
Features of the DC/DC converter are shown below.
.
The PWM switching regulator that has the high efficien-
cy is used as the converter.
.
When the output connectors are shorted by mistake, all
outputs are shut down.
.
When the input DC voltage goes outside the range of
operation-guaranteed voltage range, the output is shut
down.
.
DC power is supplied to a part of the SST-13 board and
that of the CP-337 board even when the POWER switch
is turned off. This enables to display the remaining
amount of battery or alarm indication even when the
POWER switch is turned off.
The SST-13 board has the built-in lithium battery that is
used to save the RAM data and drive the time code reader
and generator.