Acer V551 (new) CRT Monitor Service Guide
Chapter 2 Circuit Operation Theory
11
Confidence and Property
(4) Cascode CKT
(a) Output stage adopts cascode circuit Its purpose is to amplify the signal which has
been processed by MM1375XD to a enough amplitude of Vpp, then display on the
CRT. The criteria to select a cascode transistor is the smaller the value of Cob and the
bigger the value of Ft is better.This circuit adopts HSD1609. Cob=3.8pF, ft=140MHZ.
(b) Cascode CKT concludes 3 band amplification.
Mean Freq.: capacitance open, inductance short. The gain = Rc /Re
High Freq.: (R gun),peaking coil L104,L105,R115,C113,R119
Over Freq. Compensation: (R gun),C161,R161.
R171
D101
Q102
R113
Q101
C113
C112
R151
C161
R161
R115
R114
R118
R119
R116
R117
L104
L105
DC RESTORE
12V
B O/P
(OPEN)
1SS83
H945
(OPEN)
HSD1609
82P
50V
(D)
0.1U
1.2K
3W
(D)
50V
150p
8.2K
1.6K
1/4W
56
100
1/2W
33
30
390
15UH
2.7U
+75V