Commodore 1940 - Deflection Circuit

6. Deflection Circuit
6.1 Vertical Deflection Circuit
V-SYNC ---j 0406 H IC402 ~ V-DY
(Block Diagram)
0406 : Polarity inversion of vertical synchronizing signal.
IC402 : Vertical oscillation, and Drive Amplifier.
Vertical ramp generator.
<FIG. 12 Vertical Deflection Circuit>
0406 inverts the vertical sync pulse to develop a positive-going pulse at it's collector.
The inverted signal synchronizes the vertical oscillator through pin 5 of IC 402 and
pin 3 to cover wide pull in
range.
The Vertical oscillator develops a sawtooth output at pin
4.
The oscillation time constant is determined by C403, R416 and R419.
The Ramp wave is determined by C404, C405, R420 and R423.
C402 blocks the DC component of the vertical synchronizing signal.
D401, C408 and the flyback generator in pin 15 make voltage doubling.
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