| 摘要 |
A service switch to permit set-up adjustment of a color image reproducing kinescope in a color television receiver. The receiver comprises a horizontal deflection circuit for providing a periodic horizontal deflection signal having a frequency synchronized by a sync signal derived from a composite color video signal, and means for deriving a receiver operating voltage from the periodic signal of a magnitude dependent upon the frequency of the periodic signal. The switch has "normal" and "service" positions, and is coupled to respective direct voltage control terminals of luminance and chrominance channels and a vertical deflection circuit of the receiver. In the "service" position, the switch renders the luminance and chrominance channels inoperative to couple signals, and vertical scanning is disabled, to permit set-up adjustment of the kinescope. The sync signal is derived independent of the condition of the chrominance and luminance channels, and is coupled to the horizontal deflection circuit independent of the position of the switch, so that the derived voltage exhibits substantially the same magnitude in both "normal" and "service" positions. |
