Wells-Gardner Electronics Corporation

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.

8-5 Horizontal deflection output stage:

8-5.1 Line driver stage.

As a driver device, small MOSFET Q307(IRF630A) is used.

The driver transformer T302 is equipped with a snubber circuit (R327/C309) at the primary side to damp excessive ringing.

8-5.2 Horizontal power output stage.

The horizontal power output stage is a conventional one with a diode modulator.

As a deflection transistor, the Q308 (KSC3997) is used.

To compensate for horizontal linearity, T301 is connected in series with the horizontal DY. It is controlled by DC voltage of Q304 collector, which the base voltage of Q304 is integrated from output at pin 40 of IC601.

8-5.3 S-Correction capacitor switches.

Q316 is off when horizontal frequency is 35KHz

Q316, Q317 are off when horizontal frequency is 37KHz

Q316, Q318 are off when horizontal frequency is 43KHz-52KHz