3, the power supply is damaged , there is no normal power output trigger signal ;

    4 , there is no B + power supply IC , there is positive to the battery disconnected .

 

    Comparatively speaking , this is easier to deal with failure , and power line problem is relatively common, generally fly line can be solved ; plate in some key models, key board and motherboard connector socket Weld also easy to cause this phenomenon , such as the V998, Capitel 6088 , Star King S2000 and other models , plus welding solve the problem ;

    Also have more exceptions , such as the T191, T190 mobile phone, press the power button no current response is a headache to many novice when repair this phone , pay special attention to the positive battery contacts to the right of the big six-foot pipe , if it is above the voltage outputs are normal, can initially confirm the CPU and power is good , there is the upper left corner of the CPU diode is switched one line, which pass into the CPU-A2 side , and easy to break ;

 

    Maintenance Example :

    (1) T191 into the water does not boot : into the water does not boot , disassemble , after careful cleaning and power on the machine , press the power button without any current response , the measured power button no normal around 3V voltage on the power supply IC to the right of the capacitor C314 also undetectable voltage , ground resistance measurements C314 is normal, there is no B + power measured on C315, universal measurement of earth resistance meter infinity, directly connected to the fly line U83 2 feet , power , phone is switched on ;

 

    (2) V998 into the water does not boot : power- test machine , press the power button , no current response, disassemble , No 3 6V voltage measured on the right side of the power IC power resistors R804, suspect a problem with the power supply IC , air gun to remove the power supply. , for a new power IC, the fault persists, had removed again , the amount of R804 to the power of C8 foot barrier, reinstall the power supply IC, the wiring test machine , boot normally.

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