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According to the CRT spec
H dynamic focus Vpp = 300 V
2.1.4.1 Vertical Dynamic Focus
The signal from IC201 (pin 32) is a vertical frequency parabolic waveform.
Q321 : an inverting amplifier stage.
2.1.4.2 Horizontal Dynamic Focus
The wavefom of C313 (CS-2, CS-1) is a horizontal frequency parabolic waveform, and is amplified
by T304.
2.1.5 Brightness & Spot Killer CKT
2.1.5.1 G1 CKT
The bright control signal from UC controller is about 0 ~ 5V, when the voltage of bright control signal
increases, the current flow through R241 increases and the voltage of G1 decreases.
2.1.5.2 Blanking CKT
To avoid the disturbed picture display on the screen, we have to blank the monitor in the following
situations.
(1) when display mode is changed.
(2) when the monitor enter the power saving mode.
(3) blank the vertical retrace line
When the "blank" signal becomes "high" Q202 "ON", Q203 "OFF".G1 voltage is about ( -190 *
R253/(R253+R241)) -184V. The signal which is IC201 (pin 16) is inverted and amplified by Q202,
and coupling to G1. During the vertical retrace interval , the G1 voltage will be drop down about
48V.
Circuit Operation Theory
+12V
R351
62K
R352
2.4K
Q321
FOCUS
BF423
R353
620K
1/4W
-190V
Fig 4 Dynamic Focus circuit
No Copy/Reproduction Allowed
H dynamic focus Vpp = 130 V
DAF
+
C327
47U
50V
(EL)
R354
20
1/2W
T304
C336
3
2
(OPEN)
R379
500V
(OPEN)
(D)
1/4W
4
1
19.20113.011
C328
470P
500V
(D)
API Confidential
CS-2
C329
0.022U
400V
(MPP)
R327
20
1/2W
CS-1
2-3
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