ViewSonic A91f+-1, Service Manual, Page: 23 / 83

2
﹒
VERTICAL
﹒
2.1 Auto SYNC Deflection control and B+ control circuit Horizontal and vertical sync through IC401 TDA9113
transmit
﹒
Deflection
controller IC401 TDA9113
：
a
﹒
The control input
（
V-position
﹐
H-position
﹐
V-size
﹐
H-size
﹐
Pincushion
﹐
Pin-Balance
﹐
Trapezoid
﹐
Parallelogram. TOP Corner. Bottom Corner. Zoom, moiré
）
are use I
2
C control
﹒
b
﹒
SYNC input
：
H-sync
（
pin1
）（
From IC301 pin33
）﹒
V-sync
（
pin2
）（
From IC301 pin32
） ﹒
c
﹒
Output
：
∗
B
+
Driver
（
pin28
） ﹒
∗
H-Driver
（
pin26
）﹒
∗
EW-Driver
（
pin24
）﹒
∗
Focus
（
pin32
） ﹒
∗
V out
（
pin23
） ﹒
2.1.1
Horizontal
﹒
a
﹒
Then take a HFLB pulse from horizontal output Q407 collector C418 and C419 mid voltage to
IC401 for AFC to make pin12 control H-Drive
﹒
b
﹒
Pin5 and pin6
（
C410
﹐
R410
）
control horizontal hold in range
﹒
2.1.2
Vertical
﹒
a. V-sync outputs from MCU IC301 pin32 to IC401 pin2
﹐
then than smite from pin23
﹐
pin 13 to
IC501 TDA8172 pin1and pin7
﹒
b. IC401 pin3
﹐
pin7 outputs to vertical hold in range is controlled by pin22
（
C440
）﹒
2.1.3
B
+
control
﹒
Take a pulse from T403 pin2 and accumulates to become a DC voltage via Q409
﹐
Q401.Q402.
R418 ,and .R424 to IC 401 pin 28. (Step up circuit control).
2.2
Vertical deflection
﹒
a
﹒
IC401 pin23 and pin13 output to IC501
（
TDA8172
）
pin7 and pin1
﹐
then IC501 pin5 and pin7 make
vertical deflection output
﹒
b
﹒
Vertical blank
：
IC501 pin3 take a blanking pulse
﹐
After passing Q501 buffer can supply video blanking
signal
﹒
2.3
Boost converter
﹒
The Booster converter mainly composes of n-channel MOSFET Q409 Transformer T403 capacitor C442 and
rectifier diode D408. IC401 pin28 B
+
driver output via Q401, Q402, to driver Booster converter
and provide a DC-voltage to provide B
+
H-output circuit use
﹐
As H-freq. change
﹐
IC401 pin28 B
+
-driver
will change its output
﹐
Booster converter will also change the B
+
it provides
﹐
H-freq. will varies from
30K ~ 86KHz
﹐
B+ will varies from 40V ~ 180V
﹒
20
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