HUAWEI TECHNOLOGIES CO., LTD.
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4.2.2 Troubleshooting Power-on Faults
Startup faults usually include startup failure, charger startup failure, large current startup failure, automatic startup,
automatic shutdown, down system, and slow response.
Startup failure:
startup failure due to key problems: The current is 0mA. Usually it is caused by startup key failure or power supply.
Startup failure due to software problems: The current is dozens of mA. It is usually caused by the un-matching
software and hardware. Re-download of the software onto the mobile phone can solve the problem.
Startup failure due to power supply problem: The current reaches a certain value and cannot work properly.
Measuring showed a number of LDO voltage outputs are abnormal. Check the ground capacitance or the CPU.
Charger startup failure: When the charger is connected with the mobile phone, the power supply voltage turns to a
smaller value. The measuring of the ground resistance confirms that it is a MOS or CPU problem.
Large current startup failure: Measure the far-end ground resistance of the power supply outputs. Find out the short-
circuit place. Usually it is a CPU or SMT problem.
Automatic startup failure: Confirm that the mobile phone enters the common mode.
Automatic shutdown: Measure the important LDO output voltage. Ensure that each output is not faulty.
Down system: Clear the user data in the flash. Re-download the software. If the problem remains, change the CPU.
Slow response: Usually it is a CPU or flash problem.
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