1.先将电话线从接线盒中拆开,把两根线对调后再安装好,若能挂机,则故障为极性保护电路中的二极管击穿,分别检查四只二极管,更换损坏的管子,故障即可排除。2.将电话线插头从话机内拔出(或从接线盒内拆开)几秒钟后,再将电话线按原状恢复,这样可使电话线路挂断,然后将 P/T 开关置于 P 位,摘机拨号,若拨 1. The first phone line from the junction box opened, the two lines after the transfer and then installed, if you can hang up, the fault is the polarity of the protection circuit diode breakdown, respectively, check the four diodes, replace the damaged tube , Fault can be ruled out. 2. After removing (or disconnecting from) the telephone line plug from the phone for a few seconds and then restoring the phone line as it is, this will hang up the telephone line and then place the P / T switch at P Bit, pick up dialing, if dialing