来电显示电话机逐渐走进城乡家庭,很受广大用户的欢迎。而各类来电显示电话机也陆续进入维修期,本文介绍TCL HCD868(5)TDL来电显示电话机常见故障检修实例。例1 故障现象:外线呼入无铃声。分析与检修:检查外线无故障时,引起该故障的原因是振铃相关电路有故障。参见图1,由集成电路IC301(KA2418)及其外围元件组成振铃电路。首先检查压电扬声器BUZ301完好,说明故障在振铃电路 Caller ID telephone gradually into the urban and rural families, very popular with the majority of users. And all kinds of caller ID telephone have gradually entered the maintenance period, this article describes the TCL HCD868 (5) TDL caller ID telephone troubleshooting examples. Example 1 Symptom: No external ring incoming call. Analysis and Overhaul: When there is no external fault, the cause of the fault is that the ring-related circuit is faulty. Referring to FIG. 1, a ring circuit is formed by an integrated circuit IC 301 (KA2418) and its peripheral components. First check the piezoelectric speaker BUZ301 intact, indicating the fault in the ringing circuit