Theory of Operation-608
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AC D R I V E
R927
C927
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R844
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F ROM T850
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P I N 1 0
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FOCUS
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R932
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F ROM R783
R925
CRT FOCUS I
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(+20 V TO +80 V )
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- - E LEMENT I
, O F DYNAMIC FOCUS
OF V950 ,
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MODU LATOR
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DEMODU LATOR I
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NOTE
A L L VOLTAGES G I V EN ON T H I S
I L LUSTRAT I ON A R E APPROXI
MAT I ONS, NOT N EC ESSA R I LY
T HOSE FOU N D I N T H E ACTUAL
C I RCU IT.
PARTI A L
0
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FOCUS COR R ECTI ON OUTPUT LEV E L
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+20 V TO +80 V
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*20 V TO 80 V
DI FFERENCE
- - - . FOCUS R E F E R ENCE
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0 V
- - - - - FOCUS E L EMENT LEVE L
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-3250 V
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*20 V T0 80 V
DI FFERENCE
-- - . FOCUS E L EMENT L EV E L P LUS LEV E L OF
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-3230 V TO
-31 70 V
*Voltage
difference corresponds to the position of the crt beam.
(2025- 1 ) 2305-1 0
Figure
4-6.
S impiified diagram of Focus-Element
DC
Restorer.
repetitive cycles from C929, C930 will charge to the
positive level of waveform 3. Capacitor C930 filters
the output of the D emodulator, and also provides a
path for the high-frequency portions of the focus
correction signal to be coupled to the crt focus
element at V950.
The remainder of the components not shown on the
si m plifi ed diagram in Figure 4-5 provides circuit
protection in the event of a high-voltage arc or other
malfunction.
4-8
+ l 00-V O LT R E G U LATE D S U PPLY
The ac voltage fro m pin 2 of T850 is half-wave
rectified by CR888 to provide unregulated power for
the +100-Volt R egulated Supply. Filtering is provided
by C889, L889, and C890.
The regulator for this supply is a feedback amplifier
system. Current to the loa d is delivered by series-pass
transistor 0900, which is located in the output side of
the supply. T he supply voltage is established by the
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