一、原因概述 挂机异常主要包括不能挂机、挂机不断和时摘时挂现象,当主机出现挂机异常时主要应检查挂机控制电路。挂机控制电路由微处理器、继电器驱动放大管和继电器组成,此类故障多因挂机控制微处理器损坏、驱动放大管击穿或继电器触点吸合不能断开所致。检修时应重点检测挂机信号是否正常、继电器驱动信号是否正常。当手机出现不能挂机时,除检查挂机控制电路外,还应检查导频控制电路和发射延时电路。 First, an overview of the reasons for abnormal hook, including hook can not hang up, keep hanging when the hook and the phenomenon of the time when the host hang up abnormalities should mainly check the hook control circuit. The on-hook control circuit is composed of a microprocessor and a relay-driven amplification tube and a relay. Such failures are mostly caused by on-hook control of the microprocessor and breakdown of the driving amplifier tube or the pull-in of the relay contact. Overhaul should focus on detecting the hook signal is normal, the relay drive signal is normal. When the phone can not hang up, in addition to check the hook control circuit, but also check the pilot control circuit and launch delay circuit.