PALLADIUM 765/382
Manual de Servicio

Transistors TV1 and TV4 form a circuit which serves to eliminate CRT spot formation when the appliance is turned off. During operation the heater�s supply pulses, which are rectified and filtered by DV6 and CV6, keep TV1 saturated and hence inhibit TV4. The capacitor CV19 is therefore able to charge up at the voltage of +200V by way of RV19 and DV10. Grids 1 (G1) of the tube remain at ground potential since DV10 is conducting. As soon as the appliance is turned off, the final line stage stops providing the heater�s power supply pulses; TV1 is inhibited and TV4 is saturated by the +200V voltage still present and applied at its base via RV18. The collector of TV4 grounds the positive armature of CV19. As a result, grids 1 of the CRT are polarised with the negative 200V voltage present on its negative armature since the diode DV10 is now polarised the other way round. This way the CRT is completely inhibited for the time it takes CV19 to discharge, thus preventing spot formation. The RGB signals, decoupled by means of the transistors TV7/TV8/TV9, are added together and transferred to the power stage made up of TV5 and TV6 by means of the circuit made up of TV2 and TV3. The coupling capacitor CV13 together with the power stage input impedance forms a differentiator circuit which generates pulses of suitable polarity upon each signal transition. This drives a special deflection coil on the CRT which modulates the deflection velocity (Beam Velocity Modulation), thereby significantly improving image definition.

Horizontal deflection
The output line transistor is driven by the transformer TRL1 whose primary winding is driven by the transistor TL1, connected to the horizontal drive output of ICC1 via the emitter-follower TC5. The horizontal deflection stage is carried out in a conventional manner with the deflection transistor TL2, the diode (DL4/DL5) EW modulation circuit and pin-cushion distortion correction (CL8/LL6). The correction signal EW is injected into the central point of the diodes via LG2. The capacitive divider formed by CL11/CL12 is used for picking up the horizontal flyback pulse to be applied to pin 13 of ICC1, limiting its maximum value to 8V by means of the diode DL11.

Vertical deflection � EW correction

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