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Deflection Circuit (da Board) - Sony BVM-1911 Operation And Maintenance Manual

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3-14. DEFLECTION CIRCUIT (DA BOARD)
3-14-1. H Delay and Horizontal AFC (Automatic Frequency
Control) Circuit
In this model H delay function
is performed
by delaying H. AFC
pulse in the horizontal AFC circuit.
(See Figure 31)
H. AFC pulse which is fed from H.O.T. (Horizontal
Output
trans-
former) is wave shaped and is delayed about 20
µs
by !CI 12/2).
This delayed pulse is integrated
by inductor LI. and capacitor Cl 4.
thus sawtooth
waveform is obtained
and fed to terminal pin
0
of IC4. AFC detection is performed
by IC4. Output of AFC detector
is fed to control
terminal of horizontal
oscillator (H.OSC) via low
pass filter composed of capacitor CI 2, CI
5
and resistor R 10.
3
types of AFC mode are selected by changing low pass filter which
determines AfC time constant.
AFC time comtant
circuit is composed
of switch Sl. resistor RI
3,
Rl4. RlS and capacitor Cl 7, Cl 8.
:.--
IH _
__.J
1
20JJsec
1
14-_..,
~
I
'
AFC PULSE
DELAYED AFC
PULSE
l
-+u----+u
I
'
I
I
:~
u
H
SYNC
J
When
H
DELAY
1s applied
Pulse at H delay operation
Figure 31
3-14-2. Horizontal Linearity Correction Circuit
In this model Horizontal
Linearity correction
is made by applying
correction voltage to the Horizontal def1ection circuit.
Basically, Linearity correction
is made by modulating power source
of horizontal output circuit with horizontal
sawtooth voltage.
Also So-called
"Inside
pincushion"
correction
is performed
by
applying correction waveform to S correction
capacitor.
This correction
waveform
is generated
by balanced
modulator
(IC7) with vertical rate parabola waveform. See Figure 32.
Horizontal
sawtooth
waveform
is generated
by JCS (1/2)
for
horizontal
linearity correction.
Horizontal
rate parabola waveform
is f!Cnerated by integration of saw tooth by IC6 ( I /2). This parabola
waveform
is performed balanced
modulation
by IC7 with vertical
rate parabola
waveform,
horizontal
sawtooh
and parabola
wave-
form are fed to horizontal
linearity output amplifier in EA board.
Correction
of horizontal
linearity correction
and inside pincushion
correction are performed.
•C1
\~)
P11,j
l
\+>---
--
-----1-1
~•N
4
CORRECTION
WAVE FORM
~~n~
Voltage of S correction capacitor
r\f\0
r
-
~
®.
- " -
Horizontal
linearity correction waveform
Figure 32
3-31
3-14-3. Horizontal Blanking Pulse Generator
Horizontal
rate
sawtooth
waveform
generated
in H. Linearity
circuit is fed to the comparator
IC8 (1/2). In this circuit,
1/2H de-
layed pulse is obtained.
This pulse is fed to integrator IC9 (1/2) and
l/2H delayed sawtooth waveform is obtained and this is fed to the
comparator
ICI0 (1/2).
Thus the comparator
generates horizontal
pulse to make H. Blank-
ing pulse wich starts just before the starting
edge of the retrace
time. Also width of horizontal
blanking
pulse is determined
by
JK-FF IC! (1/2).
:.--1 H-+j
I
~
COMPARATOR
0
--+---V~1
:~IH~
.1L___L
~
~
'
'
IC 101 I /21
AFC
IC 1012121 OUT
Tl
B H, F+iASE
+12
~
06
COLLECTOR
-12
Figure 33
3-14-4. Top & Bottom Pincushion Circuit
Horizontal
rate sawtooth waveform generated in H Linearity cirl'Uit
is also fed to !Cl 0. !Cl 0 generates advanced H pulse for the phase
correction
because vertical Deflection Yoke works as an integrator
at horizontal
rate, and deflection
current for Top
&
Bottom pin-
cushion correction
is delayed about l/2H for this reason. See Figure
33.
Advanced
H pulse is fed to IC! I 11/2) and advanced
honzontal
sawtooth
waveform
is generated.
It
is integrated
by IC I l I 2/2)
and horizontal
rate parabola waveform is obtained.
Modulated
butterfly
waveform
for Top
& Bottom
pincushion
correction is obtained by Balanced modulator !Cl 2. In this balanced
modulator,
horizontal
rate parabola waveform is used as a carrier
and vertical rate sawtooth
waveform is modulated
by this carrier.
See Figure 34.
This
correction
waveform
is fed to vertical deflection
output
amplifier in FB board.
carrier
\[¥\.
I.-.,;
IH
0~
I
-iv~
OUT
~
+
V
cc
L
,v-J
ICI2
BALANCED MODULATOR
Figure
34
3-14-5. Autmatic 50/60Hz Field Selection Circuit
This model
has an automatic
vertical
field frequency
selection
circuit
so that
color systems with different
frequencies
such as
NTSC or PAL and SEC AM can be received. IC'I8 is automatic
field
frequency
detection
device and its output switches (IC13) time con-
stant of integrator
in vertical deflection circuit.
3-14-6. Scan Mode Selection Circuit
There are 3 modes of scanning in this model: NORMAL SCAN/
UNDERSCAN~ETUPSCAN
There are level adjustments
for Hl width, V, height side pincushion
and top
&
bottom pincushion .
Levels of correction
waveforms are switched so that these adjust-
ments are made independently
for each scanning mode. IC14, ICIS
and ICl6 activates for this purpose.
3-14-7. Vertical Deflection, Side Pincushion Correction
IC l
9 ( I /2)
generates
vertical rate sawtooth
waveform for vertical
deflection.
V sawtooth
waveform
is generated
by the integrator
IC9 ( 1/2) which is reset by V sync.
Also vertical rate parabola is generated by integrating
V. sawtooth
waveform by IC9 (2/2).
This V parabola
is used for side pincushion
correction,
and also
V.
parabola
is
converted
to sine waveform by IC20 (1/2) and is
mi,ed
with V parabola waveform. This mixed waveform is used for
side
pincushion
correction
and
fed to side pincushion
output
amplifier in EA board.
Vertical drive voltage for vertical deflection
is generated by mixing
vertical rate sawtooth
waveform generated by !Cl
9
(1/2) and sine
waveform generated by IC22 (i/2).
This drive waveform
is fed to vertical def1ection output
amplifier.
Balance adjustment
of vertical linearity correction can be performed
by IC22 (
I
/2) and vertical centering can be adjusted by IC22 12/2).
l.-1v-+1
f4---I
v--------j
i---
I
V----j
1
,-b4
'
'(\'
:/\
:1
\ I
I
/
\JV
I
V
f (
X)
= X
f(x)=1-x
2
f(x)=x-x
3
-Vee
-Vee
J
J
J
IC 191 I /21
ICl912/21
IC2011/21
-Vee
V
.LIN.
J
1(2012/21
IC2111/21
V .LIN. GAIN
I
BALANCE
!C221I/21
-Vee
v,
Vo
_j_
_j_
INTEGRATOR
Figure 35
3-3°2
SIDE PIN
CORRECTION
WAVE
f--1v---j
0
P'~
J
VERTICAL
SAWTOOTH
V. CENT
+Vee

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