Tatung Vibrant VM77S Service Manual page 14

3-6 OSD (On Screen Display) Circuit
1. The I504 MTV021-21 is OSD IC. The OSD signals are worked by positive vertical pulse from I701 pin
34 that goes through R720 to I502 pin 10, and positive horizontal pulse from T402 pin 5 goes through R496
to I502 pin 5. CPU I701 pin 13, 12 (I
2. The OSD R. G. B signals and blanking signal are terminated at I502 pin 15, 14, 13, and 12 to I501 pin 1,2,
3 and 4 then the OSD picture appears.
2
C bus) transfers information to I502 pin 7, 8.
VM77S