Acer V551 (new) CRT Monitor Service Guide
Chapter 2 Circuit Operation Theory
7
Confidence and Property
(7) Step-up CKT
(a) B+drive duty pulse comes from TDA4857 pin 6
(b) Q305, Q306 constructed class B output to drive Q317.
(c) When Q317 turns on, L304 storage energy and D317 is off. when Q317 turns off L304
release energy and D317 turns on to charge C326 to B+
(d) The higher Hor. frequency needs higher B+ so B+Drive duty must vary with frequency.
+
10
2
G2
HV
FOCUS
8
3
9
5
6
1
12
11
13
Q305
C309
C326
R347
D316
D317
Q306
L304
Q317
T303
R373
C363
R363
C364
H945
(D)
500V
0.01U
200V
33U
(EL)
200
1N4148
BYM26A
A733
19.40139.001
IRF630
19.70060.001
47
500V
220P
(D)
1/2W
(SHORT)
(D)
500V
(OPEN)
BDRV
+50V
+12V