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The following signals are the possible sync. input
signals.
(1)
SYNC. ON GREEN:
NEGATIVE POLARITY
(2)
COMPOSITE SYNC. :
POSITIVE/NEGATIVE POLARITY
(3)
SEPARATE SYNC. :
POSITIVE/NEGATIVE POLARITY
G+SYNC. (GREEN+SYNC.) SIGNAL
(Refer to circuit diagram Fig-26)
The sync. signal
is
separated from green signal via
buffer stage 0052 and video sync. separator LM1881.
The sync signal is consists of vertical sync. and
horizontal sync. Then it is fed to the base of sync.
amplifier 0553 via R580-R581-0556.
G+SYNC. SEPARATOR CIRCUIT
Fig-26
~----+-------
.. :,',
?t:.;:~_-:--'::~_
~"""
'D
F~;F~;:
~-.
~-
......
-
....
---
..
------~-
..
- - -
- - - - - - - - - - -
TEST
TEST
CONDITION
Fh
=
64KHz
J1
POINT
J1
J2
J3
1
Vpp
TEST POINT NAME
G+SYNC.
BUFFER OUTPUT
SYNC. OUTPUT
[:1]~BIE[~l],1
;
: ,
:!
1:
1
t
~
:
!
; I'; ), ' : Iii
i,
[I
i
I'
I
i--r;--"~"":·';
. .
~"-iT-,
. .
tr"-"~
. . . .
r-. .
i-j . . . .
r-'
iii!
ii"
i
i ! : 1
i
I
[-·-"T:h-· ;, . .
+_ . . . . -' . .
['--1-
';-i--
-l-;---T-l
I
1:1 ,":
I..
I:
!
I
,
!
!~
i ......
1
1
-I.
1"1:
:.....
l. \"\
I
t~P_~'~~TJ;r~rrU
J2
0.8
Vpp
J3
4.5 vpp
..
:-~
... --.-- ... : --.-.-----:---..
-"'7----~
......... - ........
~
....
~
. . , - ..... '
---.:..---- -;!
-·~
..
·-~T-· --.~
:
.
:
I
'
NETWORK
R566-C555-R567-C554-R598-R599-
0552 is the
V.
SYNC. SEPARATOR circuit. Notethat
the network values are chosen to be a low-pass filter.
The output from the low-pass filter is fed to pin 9 of
0562c.
(Refer to circuit diagram Fig-27)
The vertical sync. is derived from pin 11 of 0562d via
V SYNC.
SEPARATOR circuit and V SYNC.
POLARITY DETECTION circuit.
VERTICAL SYNC. SEPARATOR CIRCUIT
5V
R56G
R~6?
R59g
2~~~~~
H/V~~~·2K
•
~
m'>lc
1
~~
1
t
.
C~55
.
C554
R5~~
[ 0.
o018UI'J. 'J,)<:2U J.
~K
. 50"'/
,50"'/
'"
V. S Y N C - + - - - - - - - - - - - - '
Fig-27
V.S~NC
O<JTPUT
3.29 V SYNC. POLARITY DETECTION CIRCUIT
(Refer to circuit diagram Fig-29)
Low-pass filter network of R589-0556-R575-C557-
R585-0559 extracts vertical
sync.
polarity by
removing the horizontal pulses.
=
3-25
=
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