手机没信号顾问检修方法

手机没信号顾问检修 无信号的检修方法 接收通道信号图 射频功率放大器 天线 频率虑波器 中频IC 备注:黄线表示接收信号走向图 从天线接收到的射频信号流入射频功率放大器，经分频后输出四路射频信号(分别是:850MHZ、 900MHZ、1800MHZ、1900MHZ)流入频率虑波器。虑波后的射频信号进入中频IC进行混频、中放 输出I/Q信号流入CPU。 接收通道检修图 Tai Nan Street-little-salt city at North Street, North Street, road-minjiang River Bridge-Zhongshan, Renmin road, Wu Road, street, Street East-West the saturation of more than 1, old town road network saturation has reached an average of 0.89. South Bank the 3 ?射频功率放大器 天线 1 ?2 ? 备注:在维修无信号故障，我们经常用到的是假天线检测法。 实列:故障现象:无信号 检修流程:1. 在900MHZ虑波器(实际跟据当地的网络决定)与中频间连上一条细线作为假天线 (如1)。开机，如果还没有信号，即问题出在中频、26MHZ晶体、CPU，需要更换中频、 ? 26MHZ晶体、CPU等。如果有信号了，即问题出在虑波器、射频功率放大器、天线间， 用假天法一步一步往下推(如:2、3)直到找到问题点。 ?? 发射通道的检修流程 West the saturation of more than 1, old town road network saturation has reached an average of 0.89. South Bank the-Zhongshan, Renmin road, Wu Road, street, Street East-minjiang River Bridge-orth Street, roadsalt city at North Street, N-little-Tai Nan Street2 专业的客户服务 LT E521维修手册 频段选择 3 ? 2 ?天线 1 ? 射频功率放大器 中频 3West the saturation of more than 1, old town road network saturation has reached an average of 0.89. South Bank the-Zhongshan, Renmin road, Wu Road, street, Street East-minjiang River Bridge-orth Street, North Street, roadsalt city at N-little-Tai Nan Street