Akai VS-2EGN

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2-3 SECAM DETECTOR
1) SD-1 (on Video PC Board)
The
BURST
signal
from
IC10
(AN6360)
pin
(3)
is
con-
nected
to
FLI7
which
is
a
4.5
MHz
SAW
(Surface
Acoustic
Wave)
filter.
Accordingly,
when
there
is
a
SECAM
signal,
BURST
signal
is
obtained,
the
amplitude
of
which
varies
form
1H
to
the
next.
This
is
amplified
by
TR60~62,
and
routed
to
through
the
8
kHz
BPF
composed
of
VL1,
C186,
L30,
and
C187,
to
the
peak
detection
circuit
of
D28,
D29,
and
C160.
As
ta
result,
the
base
of
TR51
becomes
“‘H’,
and
SD-1
the
line
connected
to
the
collector
becomes
‘L’.
This
is
used
for
the
identification
of
SECAM
B,
G
signals.
24
VIDEO
JUDGE
(ON
SERVO
PC
BOARD)
cai
ANS750
pesados,
SYNC
SYNC Ns) one
Se
082 aLiav
R220
2) SD-2 (on EGN PC Board)
The
HD
(Horizontal
Drive)
pulse
from
IC9
pin
on
the
Video
Board
énters
the
emitter
follower
of
TRIO
on
the
EGN
PC
board.
The
delay
value
and
the
width
are
determined
by
L4,
C27,
and
R40,
and
the
pulse
be-
comes
a
BURST
GATE
pulse.
Only
the
BURST
signal
of
the
PB
SECAM-L
signal
is
sampled.
Subsequent
oper-
ation
is
the
same
as
the
SD-1
operation.
That
is,
SD-2
becomes
‘L’
during
the
time
of
SECAM-L
signal
play-
back,
aL lev
ry
TRSI
R236
lancet | ra ae
BUFFER
amp.
VCO
©———_
ja ae L-@—-i
lav
Fig.
7-24
Video
Judge
Operation
Block
Diagram
—_—_,_—§§_§
Service
Manual
VS-2EGN
27