Olympus OEP-3 Service Manual page 126

4-2-3. Analog Video Signal Processing Block (Part of VPR-63 Board)
1. Input signal processing block (Decoder block)
(1) SYNC ON GREEN discriminator circuit
This board mounts a discriminator circuit that separates a sync signal from a green channel when no
sync signal is input at the time of an RGB signal input.
IC102 discriminates the existence of a sync input signal and controls a video switch (IC103) that
switches green input and sync input signals.
R112
10k
Q102
2SC1623-T1-L5L6
D101
1SS123-T1
Q104
2SC1623-T1-L5L6
C105
22uF
R116 R119
6.3V
2.2k 2.2k
R115 C106 R122
22k 330pF 47k
4-18
R124 R130
10k 100k
C121
0.1uF
IC102 (1/3)
1 2
MC74HC4538AFEL
C CR 6
Q
5
4 7
Q
RD
3
C122
0.001uF
R127 2.7k
IC102 (2/3)
15 14
MC74HC4538AFEL
C CR 10
Q
11
12 9
Q
RD
13
C124
22uF
6.3V
Fig. 1-1 SYNC ON GREEN Discriminator Circuit
C126
22uF
6.3V
1
IN1
3
IN2
2
CTL
C129
0.1uF
IC103
NJM2233BM(TE2)
6
+V 7
OUT
R135
1k
GND
CL108
8
R136
1k
OEP-3 V1 (UC)