Wells-Gardner D9100 service manual Vertical section

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.

8.3Vertical 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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