Acer V551 (new) CRT Monitor Service Guide
(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.
12V
B O/P
R114
56
Q101
HSD1609
C112
0.1U
R113
(OPEN)
R116
Q102
30
H945
C113
82P
R117
C161
50V
390
150p
(D)
50V
(D)
R118
R161
R119
100
8.2K
33
1/2W
Confidence and Property
Chapter 2 Circuit Operation Theory
L105
2.7U
R115
1.6K
1/4W
R151
+75V
1.2K
3W
R171
(OPEN)
DC RESTORE
L104
15UH
D101
1SS83
11