No emission is the phone bootable network, but can not connect when you call or launch, how to determine whether the phone launch it? Can be judged by phone, pick up the telephone handset , phone dialing 112 , if the phone 's microphone to listen less interference sound, then the phone without emitting or transmitting section is faulty.

No phone launch failure is failure more frequently encountered in the repair process , the following analysis .

1 check transmission circuit

    Phone transmitter circuit , the transmitter frequency modulation, transmit VCO, amplifier, power control , transmit filter and other circuits are likely to cause adverse phones emit no specific repair methods can refer to the previous chapter about content.

2 Charles logic audio circuits

    For logical audio circuit , the focus is to check the output of the TXFQ signal is normal , TXUQ a total of four , which is often when it comes to emission IQ signals. Playing the "112" , this signal can be seen , it indicates that the logic circuit is normal audio , because it is the logical processing of the audio portion of "end products ." Use common simulation can also be seen TXFQ signal oscilloscope will rotate the scope's timebase switch to the longest time / div , dial " 112" , if you can get through , " 112" , this time you can see a spot left move to the right , if you can not get through , " 112" , the waveform is flash not come again. If you do not see TXFQ signal , you should check logic audio circuitry . Since the logic audio circuits have largely integrated, therefore , should focus on strengthening the weld repair and cleaning .

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