U9500 Maintenance Guide
9 Troubleshooting
Issue 1.2 (2012-6-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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If the vibrator does not vibrate, connect the phone to a USB charger, and if the phone
enters the charging state, the FPC of the Power key or the battery is faulty.
If the phone does not enter charging state, the main board is faulty, or the battery is faulty.
In this case, disassemble the phone to inspect whether the battery and the Power key are
in good condition. If they are, the power-on failure is caused by a faulty PCBA.
To locate the fault on the PCBA, connect the phone to a USB charger, and check the current.
There are three scenarios: large current, low current, and no current. The following sections
provide detailed analysis on the three scenarios.
9.2.2 Excessive Current
Causes
Large current is usually caused by short circuit. The current reaches 500 mA or above (the
over-current protection value of a USB charger) when using DC power supply. For U9500,
large current is usually caused by ground short circuit of VBAT and VPH_PWR.
Figure 9-5 and Figure 9-7 show the components, short-circuit on which can cause the
excessive current power-on failure.
Figure 9-5
Component that might be short-circuited
VPH_PWR test
point
