Bh Board - Sony BVM-1916 Operation And Maintenance Manual

3-3. BH BOARD
3-3-1. Switching Circuit Between Y (Luminance) Signal,
Color Difference Signal and RGB Signal, AGC Pulse
Insertion, Y-C Matrix
Switching Circuit of V Signal, Crosshatch Signal and SET UP
Signal, Buffer
Y signal, crosshatch signal and SET UP signal are selected by the
switcher (lCl (1/3) (2/3)) and selected signal is output via buffer
Ql.
Switching Circuit of R-Y Signal, Red Signal and SET UP Signal
(Same as 8-Y, G-Y Signal)
R-Y
signal,
Red signal, SET UP signal are selected by IC2 (1/3, 2/3)
and selected signal is output via buffer 04.
Y Signal Screening (Same as R-Y, 8-Y, and G-Y Signals)
The signal is performed SAMPLE and HOLD (S/H) at the back
porch of signal by transistor 02 and IC5 (2/2). Y screening is per-
formed by replacing S/H output signal, by the original signal
For color difference signals screening is made at the Horizontal
Sync portion.
Red Matrix, Blue Onty SW, Buffer (Same as Green and Bluel
Red is obtained by Y-C matri'\ circuit composed of resistor net-
work CP9 from color difference signals.
AGC pulse from pulse generator is inserted into Red signal for
contrast control.
IC7 activates by the Blue only SW on the front panel Blue only
SW
is
used for the display of blue signal
as
a monochrom1;; pic1Ure
3-3-2. Contrast Control, Brightness Control, Peak Limitter
Red Contrast, and Brightness Control Amplifier (Same as Green and
Bluel
This is a variable gain control amplifier composed of variable resi<;tor
element ICIOI and transistor Ql02 and Ql03. By controlling the
voltage at pin
©
of !Cl 01. contrast control is performed. and
brightness control is done by controlling the bias voltage of tran-
sistor
Q
102.
Red limitter !Same as Green and Blue)
\\-'hen ocess input signal comes in amplitude is limitted hy thl'
limitter composed of transistors 0104 and 0105
Red Contrast Control (Same as Green and Blue)
AGC pulse inserted in Red sign.ii is damped by transistor Ol07
and 5amp!ed by transistor 0108.
Amplitude of above AGC' pulse is compared with the reference
voltage applied from CONTRAST control on the front panel in
lC\02 (2/2).
Contrast control is performed by controlling the gain of Red con-
trast brightness control amplifier so that these voltages may match.
Red Brightness Control (Same as Green and Blue)
The black level of Red signal is performed SAMPLE and HOLD
(S/H) by transistor Ql06. This S/H voltage is compared with the
reference voltage applied from Brightness control on the front
panel in IC I 02 ( 1/2). Brightness control is performed by controlling
the bias of Red contrast Brightness control amplifier so that these
voltages may match
3-5
BLOCK DIAGRAM OF BH BOARD
-
1(2(1/3,2/31,04 05,6 1(2(3/3)511/2)
J R-Y/R/SETl.f'
R-Y /R
SW &
8UFF
SCREENING
r
L~
!
iC3(1/3
213)
07 05,9 IC3(3/3) 6(2/21 -
G-Y/G/SETUP
G - Y /G
SW &
SCREENING
-
BU FF
i
i
i
1(4(1/2,2131 ,CIO QI I, ,2, IC4(3/3),6ll/2l
J
8-Y/8/SETUP
f
H
8-Y/8
SW S.. I-
8 U FF
SCRE:::N1NG
l L
LJ
!
1(1(1/3,2/.'.l)
(J,
01 3 1(1{3/3),512/2)
Y/CROSS HATC!i
SCRE~N,NG
~
-
SET UP SW
i
L~ !
-
CP9, IC7, 013 1(101 0101
r-..,
103
I
R MATRIX,
~
R.CONT/BRT
B .0.SW,
CONTROL AMP .--J
BUFF
i
i
CP 12 1(8 014 1c201 0201-203
H
I
G MATRIX,
'=
G.CONT/BRT
8 0. SW,
lJ
CONTROL AMP
-
BUFF
r
!
CPl5,015 IC301, QJOl"-303
I
5 MATR:x, ~
1
b.CONT/ 8RT
-
LJ
B~FF CDNTRCL ~MP
r r
IC9, iCIC(</3:
Ql6, i7
CONTRAST, 8RIGHNESS,
I
-
-
t,,r;c
P'J-~SE GEN
tt
,...
S2
R"
qv
2
R'l 3
0
J,
Q1RE 7 5 I RE IOOIRE
-
-
-
0107 108 IC102(2/2) 0104 105 0106 ICI02(1/2)
rY
R CONTRAST
1R
RrYR,BRIGHTNESS
Al GND
CONTROL
LI MITTE
81
GND
CONTROL
A2 C H. IN
I t
B2
D. Y. IN
A3
R. IN
B3 S.S .N
I
A4
RGB. SW
B4 O.R-Y. IN
I
A5
G. IN
B5
s.u.sw
I
A6
w.sw
0207 208, 1(202(2/2)
0204 205 0206. IC202(1/2l
B6 D.G-Y.IN
~-
A? B. IN
G CONTRAST G/8RIGHTNESS
Lo
G LIMITTER
~
....
B7 C.H. SW
CONTROL CONTROL
~
AB
$.U. VR
I
!
BB 0.8
y
IN
As GND
'
89
GND
Al
C, CL. P
,--- 81
Y ,CL. P
All
C.BLK.P
811 B.0.S>N
Al1
CHAR. BLK
s12
Y.BLK.P
0307 308 1(302(2/2) 0304 305
G·306, ,C303(1/2l
A13 B P
}--{
B CONTRAST
1B
LIMinrn~Lj
818
t~~~:~~ss /
Bl
AFC. P
CONTRO_
Al4
DL.SW
I
i
Bl
A15
BRT.VR
815 R.OUT
Al
8.CL
p
816
CHAR. IN
Al CONT. VR
81 G.OiJT
AIB W. CL
p
I
BIS
GND
ICl0i3/3,,: I, 12, 13, 14, CY!7 ,.33
AIS
SW
CONTROL, PULSE 0fN
81 B. CJ T
IM
+
12v·
}
i
B2 -t 12 V
"21
- 12 V
B2I
-12 V
s'
AZ
GND
GND
( Y /COLOR DIFFERENCE/RGB
)
B
SIGNAL SWITCHING,
H
Y/C MATRIX, CONTRAST/
BRIGHTNESS CONTROL
-
3-6