Olympus OEP-3 Service Manual page 129

(5) HD generation circuit
The HD signal output from pin 37 of IC203 is adjusted to the proper phase and pulse width by IC207
(monostable multivibrator) and sent to the frame memory block as an HD (horizontal sync) signal for
fetching memory. AFC (Automatic Frequency Control) processing is performed for this HD signal.
(6) Demodulation axis correction circuit
Since, in a television circuit (IC203) for the consumer, the demodulation axis is not orthogonal for
NTSC, a matrix circuit (R243 to R251) is inserted into an RGB signal line so as to correct the
demodulation axis to an orthogonal axis. For PAL, the demodulation axis is orthogonal.
Demodulation is not related when an RGB signal is selected. In this case, therefore, the matrix circuit
must be turned off. The matrix circuit is switched to ON or OFF by IC205 and IC206.
OEP-3 V1 (UC)
A+5V
R241
IC207 (1/3)
3.9k
MC74HC4538AFEL
H POSI
C261
RV201
47uF
2.2k
6.3V
2
1
C CR 6
Q
5
4 7
Q
RD
3
C263
0.001uF
IC205
TC7S66F(TE85R)
R243
470
5
1 2
GND
4 3
IC206
TC7S66F(TE85R)
5
1 2
GND
R244
4 3
10k
IC204
TC7W00F(TE12R)
8
1 VCC 7
1A 1Y
2
1B
5 3
C265
2A 2Y
0.1uF
6
2B
Q206
GND
DTC124EKA-T146
4
Fig. 1-5 Demodulation Axis Correction Circuit
R246
6.8k
IC207
(2/3)
MC74HC4538AFEL
15 14
C CR 10
Q
11
12 9
AFC_HD
Q
RD
13
C268
0.001uF
R250
470
C266
0.1uF
R248
2.2k
R251
470
R249
C267
4.7k
0.1uF
010-B1
4-21