| 摘要 |
PURPOSE: To stabilize an image by providing a service mode circuit, operating to maintain a DC-preventing capacitor to be in a charging state in the period of operating in a service mode, so as to prevent the unnecessary oscillation of a power source. CONSTITUTION: In order to make a television receiver operate in the service mode, a mode-switching signal is switched to a low state to disconnect the conductivity of a transistor Q9 . When the transistor Q9 is disconnected, a current path for charging a capacitor C1 through a resistor R11 is opened. Then, the capacitor C1 is no longer charged, and the voltage of the plate of a capacitor C2 combined with this capacitor C1 becomes VD. As a result, the generation of a lamp voltage 27 is stopped. A resistor R10 prevents leak current from charging the capacitor C1. Consequently, a capacitor Cv is maintained in the state of being charged at nearly +12.5 volt by the operation of the transistor Q9 in the operation period of the service mode. |
