External Spot Control Circuit; Led Drive Circuit; System Control Circuit - Panasonic WV-BM90 Service Manual

2-4 External Spot Control Circuit

The external spot control circuit contains camera1 -4 select
circuits, busy control circuit and reset control circuit.
When the spot monitor control
example, 435 is changed from ON to OFF and H level at the
collector is supplied to pin 44 of IC6 for selecting the camera-
1 signal and the picture of camera-l can be seen on the video
monitor.
The camera-2, camera-3 and camera-4 select function same as
camera-l select.
Busy
Control
Circuit
l
(In case is used with this system)
Intercom system
When the two-wire intercom system is used with this system,
the wires connected between a master unit and branch unit
are also connected to the spot monitor control input 1 - 4 and
the ground terminal respectively. In this system if the call
button on the branch unit for spot monitor control input 1 is
depressed, the potential at the base of 435 becomes L level
for turning 435 OFF. As a result, H level at collector is
supplied to pin 44 of IC6 and the picture of camera-l can be
seen on the video monrtor.
At the same time, automatic reset circuit in microprocessor
IC6 starts functioning, determines the automatic reset time at
60 seconds and reset to the sequence mode to spot monitor
control.
However, the spot monitoring mode set by pressing the call
button on the branch unit of intercom system should not be
reset to the sequence mode during conversation. During the
conversation, the call button is released and approx. + 6V DC
(it should be less the + 12V DC) is fed through D16 to Q34 for
turning 434 ON.
Therefore the pin 39 of IC6 is kept L level and the sequential
conversation using intercom system.
If the phone is put down after finishing the conversation, the
potential fed to 434 becomes approx. 0.3V DC and Q34 is
turned OFF. As a result, H potential is fed to pin 39 of lC6 and
the sequential circuit in IC6 is reset to the sequence mode.
(In caseTime lapse is used with this system)
VTR
The time lapse VTR is used with this system, alarm control
output terminal and recover input terminal are connected to
the VTR. When the alarm signal is fed to the VTR, it
recording. At this time, H potential is provided at recover
terminal from the VTR and the H level is turns both Q32 and
pin 39 of IC6 for inhibiting the automatic reset circuit in KS to
keep the video monitor on the spot monitoring mode while
the VTR is in recording mode.
1
terminal is grounded for
starts
Reset Circuit
Control
When the recover terminal is grounded externally, 433 is
turned ON and key matrix for sequence control of IC6 is
achieved and the system is changed from spot monitoring
mode to sequence mode.

2-5 LED Drive Circuit

When this monitor is operated in the sequence mode, pin 6 of
IC6 becomes L level. It is supplied to 449 for turning it ON
and H level at collector of 449 is supplied to sequence
indicating LED 1 on the Switch board to light the LED. At this
time, pins 2,3,4 and 5 of IC6 becomes L level sequentially and
supplied to respective swrtching transistors 445, 446, Q47
and 448 to turn them ON and the camera1 - 4 (LED 2 - 5) on
the Switch board is lit.
When this monitor operates at the spot monitoring mode,
pin 6 of IC6 becomes H level and sequence LED is turned OFF.
Since one of pins 41 - 44 of IC6 become L level, one of pins 2-
5 of IC6 is L level, respective LED drive transistors (445 - 448)
is turned ON, and LED of selected camera is lit.

2-6 System Control Circuit

All function of this monitor such
select are controlled by the microprocessor 1C6.
When the power switch of video monitor is turned ON, + 5V
DC is supplied to pin 33 of IC6. At the beginning, generated
+ 5V DC is fed to pin 1 of reset pulse generator IC7 and reset
pulse obtained at pin 3 of IC7 is fed to pin 17 of IC6 for setting
the IC6 to initial condition.
The pin identification and functions of the microprocessor IC6
is described in the table.
as
camera select, mode