Sony BVH-2000, Operation And Maintenance Manual

Page: 285 / 505

(5-4-2. MD-14 Board)
8. RF Pedestal Clamper (IC13,14,15,28,29,34,Q14)
The FM modulator output is supplied to the RF pedestal
clamper by way of frequency divider ICI. It further passes
through switcher IC26 to the discriminator composed of ICl3
and Q14. Here a voltage corresponding to the frequency of the
pedestal is held in C78. Meanwhile, the oscillator composed of
Xl and IC27 is oscillating at the frequency (7.9 MHz for
NTSC/PAL-M or 7.682 MHz for PAL/SECAM) corresponding
to the pedestal, a voltage passes through switcher IC26 and
discriminator as with the modulator output and it is held in
C79. The RF pedestal clamper serves to feed back the signal to
the FM modulator
so that the two held voltages tally and thus
the frequency is stabilized
From
FM Modulator
'z
o
~
«
a:
w
o,
o
LL
o
>-
a:
o
w
I
I-
lO
To
FM
Modulotor
i
I
I
I
I
I
I
I
I
I
I
I
I
___ J
L..-.- __ ---I
r
n.
IC29-12
:~::.; ::;-;1J~==================:":
IC31-8
Jl
--lQ
)
~
MOD. OUT FREQ. SAMPLING OSC FREQ. SAMPLING
9. Video/Sync RF Amplifier
(Q17,Q21 to 25,ICl,12,25,33)
The frequency of the RF signal from the FM modulator is
halved by ICI, and is switched respectively for the video and
sync channels by the "REC SIG" signal supplied to pin-28 on
the MD-14 board, then the both signals are output to the RP
board
VIDEO SIGNAL SYSTEM
5-4-4
BURST GATE
BVH-2000(U/C)/PS/PM
BVH-2180(U/C)/PS/PM