Vertical Height Adjustment Circuit - Tatung OMNISCAN SERIES Service Manual

C3
20 Vpp
C4 23 Vpp
C5
43 Vpp
C6 3 Vpp
C7
2.3 Vpp
.. 1.
C8 11 Vpp
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3.9 VERTICAL HEIGHT ADJUSTMENT
(Refer to circuit diagram Fig-g)
The resistance between pin 7 of 0301 and ground
defines the current mirror and then the height of the
scanning.
R314 and network 0303-0302-R346-R316-R345
define the amplitude of the ramp signal on the input of
the deflection power amplifier. R314 is the vertical
size pre-setting resistor.
VERTICAL HEIGHT ADJUSTMENT CIRCUIT
Fig-9
(F flO\! !>AI eRO BOARD)
v.
S I ZF. CON1ROL
INPUT
~!l346
10 0301
10A'167S
-7
J
1201(
0303 .---+-,
j
~~~1:733
•. '
'J~,)'2
LM358
P314
500K
V.SIZE
PRE SET
f
R317 820K
~R316
16V
~ Y,'Iv--~----'R3~47.
471< R345
f
270 l<
~~~8
471<
~!
3.10 VERTICAL POSITION ADJUSTMENT
(Refer to circuit diagram Fig-10)
The raster vertical position adjustment is achieved by
using the network 0315a-D305-0306-0304-0305-
R302-R321, control voltage is fed to pin 6 of 0315a,
when output voltage on pin 7 of 0315a is high, this
voltage will turn on 0305 via 0306, part of vertical
deflection dc current will flow to ground via 0305 and
R321, the raster position will be moving up.
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3~9
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