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手机不入网分为有信号不入网和无信号不入网两种情况。根据手机入网的原理,由于接收比发射超前,因此,手机是先接收后发射。但各种品牌机进入网络和信号显示不完全相同。如爱立信、三星手机,只要接收通道无故障,就会显示信号强度值,与有无发射信号无关。摩托罗拉、诺基亚手机,虽然也是先接收后发射,但发射要影响接收,必须等进入网络后才能显示信号强度值。在检修这类不入网故障时,应首先插上SIM卡,用手动搜索寻找网络,若能找到网络,说明接收通道正常,故障在发射通道;如果用手动方法找不到网络,说明接收通道存在故障,应先对接收通道进行检查。 1.射频供电电路
Mobile network is divided into no access to the signal and network access without signal two cases. According to the principle of cell phone network, due to receive ahead of the launch, therefore, the phone is first received after the launch. However, a variety of brand-name machines into the network and the signal is not exactly the same. Such as Ericsson, Samsung mobile phone, as long as the receiving channel is faultless, it will show the signal strength value, with or without launch signal. Motorola, Nokia phones, although it is also received after the launch, but the launch to affect the reception, must wait until after entering the network to display the signal strength value. In the maintenance of such non-network failure, you should first plug in the SIM card, using manual search to find the network, if you can find the network, indicating that the receiving channel is normal, the fault in the transmitting channel; if manually find the network, indicating that the receiving channel exists Fault, the receiving channel should be checked first. RF power supply circuit