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故障现象:一台康美思 HMCD2899型无绳电话机,使用手柄、免提或子机时,用户听到的声音都特别小:子机与主机对讲时,子机听到的主机讲话声也特别小。分析检修:拿起该无绳电话机的手柄,对着送话器吹气,听筒内几乎听不到侧音,据此判断故障出在主机的话音发送公共通路。打开机壳,直观检查未发现异常元件。该电话机话音发送公共通路的电路原理如附图所示。该机通话集成块 U9采用的是 VG1062,
Symptom: A Kangmeisi HMCD2899-type cordless phone, the use of the handle, hands-free or sub-machine, the user heard the sound is particularly small: the sub-machine and the host intercom, the sub-machine to hear the host special voice small. Analysis and Maintenance: Pick up the handle of the cordless phone, blowing toward the microphone, the earpiece almost can not hear the side tone, thus determine the fault out of the host’s voice to send the public access. Open the case, visual inspection found no abnormal components. The circuit diagram of the telephone voice transmission public path as shown in the figure. The machine call integration block U9 is used VG1062,