U8815
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-02-13)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
61
Figure 9-48
I/O connector circuit diagram
Analysis
When the charger is connected to the I/O connector (USB connector), it provides the VCHG
charging voltage to charge the battery.
When the phone is connected to a computer using a USB cable, USB_HS_DN and
USB_HS_DP are used for communication (for upgrading the phone's firmware, reading
information from the phone…) between the phone and the computer.
Troubleshooting Process
Failure: The handset cannot be charged or detected by a computer.
Solution: Clean, re-solder or replace the USB connector.
Table 9-14 describes the signals in the circuit diagram in this section.
Table 9-14
Description of the signals in the circuit diagram in this section
Signal
Description
Reference Measurement or Wave Form
VCHG
Charging current input
High level, 5 V
USB_DM
Digital signal
None
USB_DP
Digital signal
None
9.4.8 microSD Card Connector
Figure 9-49 shows the microSD card connector circuit diagram.