Excessive Current - Huawei U9500 Maintenance Manual

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U9500 Maintenance Guide

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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

Issue 1.2 (2012-6-30)

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.

Huawei Proprietary and Confidential

9 Troubleshooting

VPH_PWR test

point

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