Sony UP-21MD Service Manual page 55

(2) Y/C separation block
A digital comb filter (IC109) is used to separate the luminance signal (Y) and chroma signal (C) of a
composite video signal.
The input composite video signal is passed through a band rejection filter (FL101), amplified by
about two times, and input to pin 15 of IC109. The separated luminance signal is output from pin 6
and passed through a band rejection filter. After that, the signal is input to the video switch (IC104)
that switches the luminance signal of an S video signal. In the same manner as described above, a
chroma signal is output from pin 8 and input through a band rejection filter to the same video switch.
Fig. 1-2 Y/C Separation Biock
(3) Composite sync signal separation circuit
A composite sync signal (CSYNC) is separated by IC203.
The composite sync signal of the Y signal input to pin 6 of IC203 is separated by IC203, and the Y
signal is output from pin 3. The output signal at pin 3 is positive-synchronous. Therefore, the output
signal is inverted by Q201 so that it is negative-synchronous.
ASBV-5 TP201 TP202 TP205 ,
° O O
Fig. 1-3 Composite Sync Signal Separation Circuit