论文部分内容阅读
故障现象 呼入时,手机和主机均不振铃。手机开关打到“SB”位置时,有较强的白噪声。 分析与检修 首先检修不振铃故障、呼入时虽然手机、主机均不振铃,但此时只要摘机,即可与主叫用户通话,且手机、主机均可单独对外正常通话,手、主机亦能互相呼叫。由此可初步判断故障可能出在主机的振铃单元电路上。有关振铃单元及外线输入极性电路如图1所示。振铃单元是否损坏可用一种简单方法来判定。即将电容C97按图1中C点的那一脚焊下悬空,再将电话B线从C点(电路板)上焊下直接焊到C97的悬空脚上,用电话测试
Symptom Incoming call, the phone and the host are not ringing. Phone switch hit the “SB” position, there is a strong white noise. Analysis and Overhaul First, repair does not ring the fault, although the phone call, the host does not ring, but this time as long as off-hook, you can talk to the calling user, and the phone, the host can be a separate external normal call, The host can call each other. This can be a preliminary assessment of the fault may be out of the host ring unit circuit. The ring unit and external input polarity circuit shown in Figure 1. Whether the ringing unit is damaged can be judged by a simple method. Capacitor C97 is about to press the foot of C point in Figure 1 under the dangle, and then the phone line B from the C point (circuit board) welded directly soldered to the C97 dangling feet, the phone test