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8-3
1. VIDEO CIRCUIT
1) Selection of BNC/D-SUB Input
The input selection circuit selects the BNC input or D-SUB input according to the voltage of IC731 pin19 (0V
or 5V). IC731 pin19 voltage changes whenever SW108(momentary switch) is pressed.
CPU detects BNC input or D-SUB input by input signal of Sync On Green and H/C sync. JC-1946UMW’s
user can know by OSM information whether input is BNC or D-SUB. Sync sensor outputs high level when
fH is 1kHz or more, and low level when fH is less than 1kHz.
CPU detects BNC/D-SUB inputs and memories CONTRAST, SHARPNESS and EDGELOCK condition at
each input.
(Fig 1.1.1) Input Selection Circuit (Green channel)
(Fig 1.1.2) Sync Sensor (D-SUB part)
IC731
M52755SP
WIDE BAND
ANALOG
SWITCH
4
C702G
C701G
G
C705
R709
R701G
LC763
LC761G
BNC
R701G
13
19
30
+5V
H/C
SYNC
SENSOR
2
18
R73WG
C704G
C703G
G
C707
R70E
R703G
LC765
LC762G
D-SUB
R704G
H/C
SYNC
SENSOR
R736G
R73A
SW108
D/BNC
To
Amplification
Section
MRC802
C73E
R73XG
IC801
CPU
1
2
27
7
C7G3
R7G2
MD7GG
R7GY
R7GP
To
CPU
R7G4
R7GX
Q7G4
R7GT
C7GH
C7G6
R7G7
Q7G5
C7GG
R7GW
R7GR
R7G8
+5V
+5V
R7G6
R7G9
Q7G6
C7GJ
D7GF
IC7G1
HD74HC123AFP
MONOSTABLE
MULTIVIBRATOR
G
H/C
2
13
15
14