2. white peak bending correction circuit – Toshiba TW40F80 User Manual

Page 72

4-2. White Peak Bending Correction Circuit

4-2-1. Outline

White peak area in screen picture may sometimes cause bend-

ing in picture. See figure below.

In TP48E60 series, correction signal which video ripple in

video output circuit power supply 200V is input to pin 24

(Bending correction terminal) of Q501. This corrects white

peak bending.

4-2-2. Operation Theory

Fig. 9-11 shows circuit diagram. Video ripple in video out-

put circuit power supply 200V suffers DC cut by C475, and

is inverted in Q470, then input to pin 24 of Q501 via C481.

Pin 24 of Q501 is a bending correction terminal. The volt-

age which is applied to this terminal, controls phase of video

signal to correct white peak bending.

Q501

Bending correction

terminal

EHT

C415

Receiving Board

Power, Def board

BB91

C481 Inversion

Q470

R481

R482

D470

R483

R484

D474

R478

C475

C466

D406

200V

White peak

Bending by white peak

T416

R379

Fig. 9-11 White peak bending correction circuit