| 摘要 |
PURPOSE:To decrease the check time and to improve the rate of detection, by applying a pulse wave in place of a ringing signal, between T and R lines, holding a relay of a detection circuit and measuring the continuity of its relay contact. CONSTITUTION:When a control signal is inputted from an oscillator 11 to a test device 3, the oscillator 11 oscillates and a relay 13 turns on and off. In switching on an off contacts 13', 13'' with a prescribed period, a relay 9 is held. Thus, each failure can be detected by measuring the voltage at a terminal S. That is, if one of diodes 5-8 is short-circuited, the relay is not held. If one of the diodes 5-8 is opened or connected in opposite direction, or open coil of the relay 9, then the relay 9 is not energized. |
