Wells-Gardner D9100 - Manual (Page 17)

8-2.2 Vertical section:
8-2.2.1 Vertical oscillation.
The free running frequency of the vertical oscillator is determined by the
capacitor C342 at pin VCAP (pin22) of IC301.
8-2.2.2 Vertical amplitude.
Vertical amplitude is controlled by IC601 using I²C bus control.
8-2.2.3 Vertical position.
Vertical position is controlled by IC601 using I²C bus control.
8-2.2.4 East-west parabola.
A parabola wave-form is available on pin 24 of IC301 for driving the
pincushion correction stage. Amplitude of parabola waveform is
controlled by IC601 using I²C.
8-2.3 B+ Regulator.
B+ PWM regulator output is available on pin 28 of IC301 for driving the B+
control stage. This PWM output is adjusted through VR301.
8.3 Vertical Deflection (IC201):
IC201 (KA2142) is used for direct driving of the vertical deflection yoke.
8-4 Horizontal scan voltage control stage:
The set-up converter is used in this stage. The output pulse at pin 28 of the
IC301 is synchronized on horizontal frequency. This pulse is operated via buffer
stage Q311/Q312. This output is rectified through
D315/L304.
In this way, the supply voltage to the flyback transformer can be proportional
to the horizontal line frequency.
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