维修分析（Maintenance analysis）.docVIP

维修分析（Maintenance analysis） GSM mobile phone maintenance methods and techniques GSM belongs to a class of mobile phone communication appliances, so you can imagine it is the maintenance methods have common characteristics with other household appliances in many aspects, but because of the complexity of mobile phone software and using SMT (surface settlement process) the particularity, and makes the mobile phone repair has its own characteristics. The methods adopted in mobile phone maintenance are: (1) \ voltage method This is one of the most basic methods used in the maintenance of all household electrical appliances. Maintenance personnel should pay attention to the accumulation of some in the condition of different critical voltage data, these conditions are: call state, single receiving state, single transmitting state, standby state. The key points of the voltage data are: power management IC output voltage and control voltage, RFVCO voltage, 13MHzVCO voltage, CPU voltage, voltage control and reset voltage, working voltage of RFIC, BB (BaseBand IC, baseband) voltage LNA working voltage, I / Q DC bias voltage and so on. In most cases, this method eliminates failures such as power on, no firing, protection, shutdown, etc.. (2) current method This method is also a common method used in the maintenance of household appliances. Because the mobile phone almost all of the ultra small SMD, PCB in the component mounting density is quite large, so if you want to disconnect the measuring current somewhere there are certain difficulties, generally uses the voltage to measure the resistance value of the resistor value divided by the indirect measurement of current. Current method can measure the work, waiting and shutdown current of the whole machine. Its very helpful for maintenance. The normal data: work current of about 400mA / 3.6V, 5 power; kept current is about 10mA; the shutdown current of about 10 A. (3) resistance method The method is also one of the most commonly u