System Control - Toshiba D-VR3SU Service Manual

8-5 System Control

In the VCR, complex mechanism, video, audio, servo circuits, etc. must be operated in specified timings matched
each other. The system control circuit performs entire controls for the VCR.
An automatic stop function is also provided to protect important tape if a trouble occurs on the complex mecha-
nism and the electrical circuits.
For this purpose, status of each part of the mechanism is always monitored with various sensor switches, and the
microcomputer controls collectively the unit so that the best condition is kept.
Moreover, the microcomputer controls signal switchings for each circuit according to the mechanism status.
Key matrix
AUDIO
VIDEO
TUNER
POWER ON/OFF
REC mute
TV/VCR
Remote
Remote
control
STEREO
Front button
Input
IIC BUS
Fig. 8-11 System Control Block Diagram
Main microcomputer
Loading motor control
(Voltage, direction)
(Detecting of mechanical mode position)
(Detection of cassette-in/cassette-out)
Tape stsrt sensor
Abnormal reel retation
Take up
FF/REW speed control
Abnormal reel retation
Supply
FF/REW speed control
Current control
Capstan motor control
(Speed direction)
FG pulse
CTL pulse
(Linear time counter)
REC control
Cylinder motor control
FG/PG pulse
VCR Deck Operating Description
Loading motor drive M Loading motor
broken safety tab
Mode sensor
Tape
Stsrt sensor
Capstan
M
motor drive
Cylinder
M
motor drive
REC-inhibition
Mode SW
Tape end LED
T reel
sensor
S reel
sensor
Capstan motor
FG
Control
Cylinder motor
PG
FG
8-9