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6-1
Chapter 6
Sync, Deflection & High Voltage
The Overall Sync, Deflection and Hign Voltage cir-
cuitry in the V23 is shown in the Block Diagram at
the top of the page. The V23 can display either of
two scanning formats, 480p or 1080i. The horizon-
tal scanning frequency for 480p is 31.5 kHz, and
1080i is 33.75 kHz.
Conventional 480i TV signals have a scanning rate
of 15.75 kHz. For these signals, line doubling cir-
cuitry changes the signal format from 480i to 480p.
In NTSC and Component format signals, horizontal
and vertical sync must be extracted from the Y sig-
nal by the NTSC Decoder. For the DTV Input, the
signal can be either Y,Pr,Pb or RGB/HV, sometimes
referred to as “5-wire.” (Sync on green is no longer
an option.) Obviously all 5-wire inputs have sepa-
rate horizontal and vertical sync.
Sync Select circuitry selects the Main picture sync
source. The selected output is used to synchronize
the Horizontal and Vertical Deflection Generators.
If the source signal is 480i, horizontal sync is
doubled, before synchronizing the Horizontal Drive
Generator.
Horizontal deflection drive is amplified by the Hori-
zontal Output circuitry and directed to the horizon-
tal windings in the Deflection Yokes. The signal
from the Horizontal Output is also directed to HV
Drive circuitry. HV Drive is amplified at directed to
the Flyback transformer.
Vertical sync synchronizes the Vertical Deflection
Generator. Output from the Vertical Generator is
amplified in the Vertical Output circuitry and directed
to the vertical windings in the Deflection Yokes.