Kink Correction Circuit - Toshiba CN27E90 Technical Training Manual

To restart TV set, repair failure first.

8. KINK CORRECTION CIRCUIT

1. Outline
In the N5SS chassis, a kink correction circuit is employed to
correct a kink generating when receiving a black and white
pattern.
In the black and white pattern cross hatch shown in Fig. 11-
20, when the picture changes from black to white during field
scan period, a current Is flows rapidly in secondary of the
FBT and a current IP flows in reverse direction during scan
period (due to transformer coupling) in the primary winding.
This current works to increase the voltage across S character
correction capacitor CS. As a result, the deflection current
decreases by I1 as shown in Fig. 11-21 and the raster moves
toward left, thus causing the kink as shown in Fig. 11-22. On
the contrary, when the picture changes from black to white,
l1
+
lp
Cs
-
FBT
Fig. 11-20
Fig. 11-21
Kink in the cross bar
pattern
Fig. 11-22
the reverse operation will occur.
2. Circuit Description
To correct the kink damping circuit is added between the
main B power line and the S character capacitor as shown in
Fig. 11-23.
In Fig. 11-24, a capacitor C441 is charged with a DC current
iB through Q442 connected to MAIN B during the flyback
period. When the voltage across C441 and S character
correction capacitor increases during the scan period, the
diode D442 conducts and reduces the voltage across C442 to
the original voltage level, thereby suppressing shift of the
raster.
Q404
ls
L462
Vcs
C442
Vcs
84
Kink Correction
Circuit
C444 C440 L642
C442
L461
D461
C467
Fig. 11-23
D442
R442
C441
MAIN
iB B
Fig. 11-24
T461
D442 R442
C441
SIDE DPC C448
C464
T461
C448