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U8185
Maintenance Manual
Figure 9-15 Home key
Figure 9-16 V olume key
Analysis
The U8185 has a Power key, V olume key, and Home key.
When the phone is powered off, press the Power key (PWR_ON). The KPD_PWR_ON signal
is then pulled down. This signal is connected to the control switch of the power management
module and triggers the power management module to power on. Then the entire system is
powered on. When the phone is working properly, press the Power key, the KPD_PWR_ON
receives the triggering signal and transmits the signal to the CPU for processing. The working
principle of the Home key is the same as that of the Power key. When being pressed, the key
generates a low level signal and triggers the CPU to process the signal.
Troubleshooting Process
Issue 1.0 (2012-03-23)
Power key failure
Home key failure
V olume key failure
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
9 Principles and Failure Analysis
51
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