DEFLECTION CIRCUIT WITH SERVICE OPERATION MODE

摘要

In a video display apparatus having a service mode of operation, a vertical deflection circuit includes a vertical deflection winding coupled to a DC blocking capacitor. An output stage includes first and second output amplifiers coupled to the vertical deflection winding in a push-pull arrangement at an output terminal. A vertical sawtooth voltage generator is coupled to a driver stage via an error amplifier that provides both AC and DC negative feedback for driving the output stage at a vertical rate in a sawtooth manner to generate a sawtooth deflection current in the deflection winding and for establishing a DC operating voltage level at the output terminal that charges the DC blocking capacitor. A service mode switching circuit is coupled to the driver stage for asserting the service mode of operation by maintaining the first output amplifier in cutoff and the second output amplifier in conduction to discharge the DC blocking capacitor and disable the generation of the sawtooth deflection current.