Convergence Circuit (Db, Dc Boards. Oct Block) - Sony BVM-1911 Operation And Maintenance Manual

3-13. CONVERGENCE CIRCUIT
(DB, DC BOARDS, DCT BLOCK)
3-13-1. General Description
This is a simple e,planation of the convergence system in Super
fine Trinitron picture tube used in this model.
The Deflection Yoke !DY) used in this model generates an almost
uniform llla?nctic field in order to !!Ct fine beam spot size. Accord-
inµly basically misconvcr?ence of lwri1ontal direction as shown in
Figure 21 is generated on the picture screen.
Horizontal misconvergence of
Y axis direction
Horizontal misconvergencc of
X a,is direction
R G B
G B R G 8
6 0 0
.
111
I
I
I
R G 8
600
•
11 I
I
I
I
!
i i :
I
I
I
600
•
Figure 21
3-13-2. Static Electrorical Convergence System
Trin1trun ,yqem has a unique
"itJtiL'
L·onverµenL'l' ,ystem.
The structure of electric gun is shown in Figure 22.
R G B
6 0 0
I I i
I I
I
R G 8
600
I
I
I I
6 0 0
(;6 1..; the dectrodl.' for ninver~ence. Stat1L· eil'L'tror1ca! conver~enL-L'
,·ontrol ,·an be used. In this system be,rm sput deterioration rs kss
than that of the ck,·troma.~nctic si·stL'lll.
HY
I
CV HV
KB
~(I~_ ( l
J!
G6L/
KG~~/
=i
KR
--1\.., I
~
c ,
~
t ',
t
n-
t
JI
G 6
GI G2 G3
1
G4 GS CONVERGENCE
I CONTROL PLATE
FOCUSING VOLTAGE
Figure 22
3-13-3. Convergence Correction Circuit
(Horizontal Convergence)
Misconvergence of horizontal direction on Y a,is is rnrrccted by
applying vertical rate parabola waveform to the convergence
plate (C6)
And niiscunvcrµence of horizontal direction is corrected by applying
horizontal rate parahola waveform to (;6.
See Figure 23.
HV ELECTRODE
CV ELECTRODE
HV ELEC TROD£
u
y At IS
X AXIS
HORIZONTAL MISCONVERGENCE
Figure 23
3-27
In this model. transformer is used to supply correction voltage to
the (;6 electrode for the horizontal direction rnisconvergence. In the
secondary of the transformer peak clamp circuit using diode is
applied so that both the vertical rate parabola waveform and
horizontal rate parabola waveform are mi~ed and supplied to
CV electrode. See Figure 24.
1VUUJUJr
'---- '. _J
Figure 24
---- REHIACE
-111- TIM[
_f'_.
---"L
c,,.,-u-,
_ COMPONENT
Of X AXIS
-+
:__(01,4P'Jt;fNT
or • Ax,s
::_____j_
The correction waveforms are generated in DB board and output
amplifier is located in FB hoard.
3-13-4. Vertical Convergence
Theorctrcally there rs no misconvergence of Vertical direction
since electrrc gun is aligned in line. But there is a slight amount
of misconver)!Cncc due to the variations of CRT and DY and also
due to the terrcstial magneti.sm.
There are also
2
kinds of mis,·onvergence of vertical direction on X
a,is and Y a,is as same as hoirzontal direction.
\1isconvcrµencc of Vertical direction on X a ,is is corrected by CY
(conver~ence yoke).
Figure 25 shows ihc CRT neck as seen from the rear side.
Red beam and Blue beam arc moved to the vertical direction differ-
cntwlly by CY. As Crecn beam is at the center of the CRT neck, it
is not affected by the magnetic field of CY due to the cancellation
of the maµnctic field at the center of the neck.
\1isn,nvcrµcnc·e of vertical direction on Y a,is is corrected by NTC
1Ncck Twist
c,,ii1.
A Neck T,, ist Coil is ,, ound around the center of electrode G2 -
C3 (See Figure 25) for the correction. Theortically, as the RLD and
Blue beams have HI component !They arc opposite direction) as
seen
in
Figure 25, they move to the vertical direction due to the
magnetJC field generated by NTC
However as magnetic field of the NTC is the parallel to the Green
beam. Green beam is not affected.
Correction ,,aveform µcneratur is located in DB board. output
amplifier
of CY is in FB board and output
amplifier of NTC is in
DB board.
Beam moving direction
Figure 25
BLOCK DIAGRAM OF DB, DC BOARD
r
OCT DRIVE
111 V PULSE
V PULSE
TOP
OJ8
SU.FER
049
INV.
IC I fl/21
2
xv
SAWTIOTH
GEN
l/2V PULSEO---~
D (
CONVERGENCE)
C
CONTROL
VERTICAL
,-4:3---,
ICl(2/21
2XV
PARABORA
GEN
CONVERGENCE
16: 9 16:9
,-4:3--,
16:9
UNDER SCAN
H.AMP
Lt-r
~Y.BOW
t6:9 Y.BOW
I
--~_J
IC8(1/2f
H CONV
AMP
lC2!1/2J
H PARABOR
GEN
IC5(1/ 2)
H PARABORA
GEN
!CGtl/2)
H PARASORA
GEN
IC7!1/ 2l
H PO.RABORA
GEN
ICS ti /2)
AMP
!Cl6 ll/ 2)
PULSE
FORM
3-28
0~3, 34
OUTPUT
1----0
CY. ()R!VE
D (
CONVERGENCE)
8
WAVE FORM -------------
t
15V
- 15V