| 摘要 |
PURPOSE:To prevent destruction of a CRT dependent upon short-circuit of the coupling condenser between an SEPP vertical output and a deflecting coil, by using an integrating circuit to detect superposition of DC components. CONSTITUTION:SEPP-connection vertical output circuit 7 is connected to vertical deflecting coil 11 through coupling condenser 10. Integrating circuit 13 which has a time constant sufficiently longer than vertical synchronizing is connected to connection point A between condenser 10 and coil 11, and the output of circuit 13 is applied to video circuit 16 as a luminance suppression voltage. By this circuit, in case that condenser 10 is short-circuited, a deflection current with DC components superposed is flowed to coil 11, and DC components appear in the voltage of point A, and consequently, DC components appear in the output of integrating circuit 13 also. Since they are applied to video circuit 16 as the luminance suppression voltage, destruction of CRT1 can be prevented. |
