Huawei U8655N User manual

U8655N
Maintenance Manual
Issue
1.0
Date
2012-09-27
HUAWEI TECHNOLOGIES CO., LTD.

Issue 1.0 (2012-02-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
i
Copyright © Huawei Technologies Co., Ltd. 2012. All rights reserved.
No part of this document may be reproduced or transmitted in any form or by any means without prior
written consent of Huawei Technologies Co., Ltd.
Trademarks and Permissions
and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.
All other trademarks and trade names mentioned in this document are the property of their respective
holders.
Notice
The purchased products, services and features are stipulated by the contract made between Huawei and
the customer. All or part of the products, services and features described in this document may not be
within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements,
information, and recommendations in this document are provided "AS IS" without warranties, guarantees or
representations of any kind, either express or implied.
The information in this document is subject to change without notice. Every effort has been made in the
preparation of this document to ensure accuracy of the contents, but all statements, information, and
recommendations in this document do not constitute a warranty of any kind, express or implied.
Huawei Technologies Co., Ltd.
Address:
Huawei Industrial Base
Bantian, Longgang
Shenzhen 518129
People's Republic of China
Website:
http://www.huawei.com
Email:
[email protected]

U8655
Maintenance Manual
About This Document
Issue 1.0 (2012-02-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
ii
About This Document
Purpose
Prepared by
R&D
Date
Reviewed by
Maintenance support team
Date
Approved by
Service representative
Date
Change History
Date
Version
Change Reason
Revised Section
Description
Author
2012-02-20
V1.0
Released the first issue.
R&D

U8655
Maintenance Manual
Contents
Issue 1.0 (2012-02-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
iii
Contents
About This Document.................................................................................................................... ii
1 Product Introduction ....................................................................................................................1
1.1 Appearance.......................................................................................................................................................1
1.2 Specifications...................................................................................................................................................1
2 Applicable Scope and Precautions ............................................................................................3
2.1 Applicable Scope..............................................................................................................................................3
2.2 Precautions.......................................................................................................................................................3
2.3 How to Obtain Product and Repair Information ..............................................................................................3
3 Exploded View...............................................................................................................................4
4 Components on the PCBA...........................................................................................................6
5 Software Upgrade .........................................................................................................................8
5.1 Upgrade Preparation.........................................................................................................................................8
5.2 Upgrade Procedure...........................................................................................................................................8
6 Maintenance Tools......................................................................................................................10
7 Disassembly Procedure..............................................................................................................12
8 Assembly Procedure...................................................................................................................17
9 Principles and Failure Analysis ...............................................................................................21
9.1 Block Diagram ...............................................................................................................................................21
9.1.1 Function Description of the PCBA .......................................................................................................22
9.2 Baseband Unit................................................................................................................................................25
9.2.1 Power-on Management Circuits............................................................................................................25
9.2.2 Charging Management Circuits ............................................................................................................29
9.3 RF Unit...........................................................................................................................................................30
9.3.1 RF Failure .............................................................................................................................................30
9.3.2 GPS.......................................................................................................................................................33
9.3.3 Wi-Fi/Bluetooth/FM Module ................................................................................................................33
9.4 Peripheral Circuits..........................................................................................................................................34
9.4.1 Display..................................................................................................................................................34
9.4.2 Camera..................................................................................................................................................37

U8655
Maintenance Manual
Contents
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9.4.3 USB.......................................................................................................................................................39
9.4.4 Headset Jack..........................................................................................................................................40
9.4.5 Keys......................................................................................................................................................42
9.4.6 Status Indicator and Touch Key Backlight Circuits ..............................................................................43
9.4.7 Battery Connector .................................................................................................................................44
9.4.8 Accelerometer .......................................................................................................................................45
9.4.9 Proximity and Illuminance Sensor........................................................................................................45
9.4.10 Vibration Motor...................................................................................................................................47
9.4.11 Receiver ..............................................................................................................................................48
9.4.12 Microphone.........................................................................................................................................50
9.4.13 Touchscreen Panel...............................................................................................................................51
9.4.14 SIM Card.............................................................................................................................................52
9.4.15 microSD Card .....................................................................................................................................53
9.4.16 NFC.....................................................................................................................................................54
10 Solder Points on the PCB and BGA Chip.............................................................................59
11 Functional Tests.........................................................................................................................64
11.1 MMI Test......................................................................................................................................................64
11.2 Voice Call Test..............................................................................................................................................67

U8655
Maintenance Manual
1 Product Introduction
Issue 1.0 (2012-02-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
1
1 Product Introduction
1.1 Appearance
1.2 Specifications
Category
Description
Dimensions (H x W x D)
116.9 mm x 61.4 mm x 12.2 mm
Technical standard
U8655N: W2100/W900, GSM850/900/1800/1900

U8655
Maintenance Manual
1 Product Introduction
Issue 1.0 (2012-02-23)
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2
Category
Description
Frequency bands
U8655N:
WCDMA 900MHz: 880–915 MHz (UL), 925–960 MHz (DL))
WCDMA 2100 MHz: 1920–1980 MHz (UL), 2110–2170 MHz (DL)
GSM 850 MHz: 824–849 MHz (UL), 869–894 MHz (DL)
GSM 900 MHz: 880–915 MHz (UL), 925–960 MHz (DL)
GSM 1800 MHz: 1710–1785 MHz (UL), 1805–1880 MHz (DL)
GSM 1900 MHz: 1850–1910 MHz (UL), 1930–1990 MHz (DL)
Weight
< 125 g with battery
Form factor
Bar
Antenna
Built-in
UIM
SIM, USIM
Charger
5 V, 1000 mA
Battery
Type: Li-ion
Capacity: 1250 mAh
Standby time: 220–250 hours (network dependent)
Talk time: 210 minutes (network dependent)
Display
Resolution
320 x 480 pixels
Type
TFT LCD
Color
262K
Size
3.5 inches
Connectors
Charging port
micro-USB connector
USB port
micro-USB connector
microSD card
interface
microSD card interface
Headset jack
3.5 mm (LRGM)
Maximum
transmission
power
23–33 dBm
Static
sensitivity
≤ 104 dBm
Temperature
Operating temperature: 0°C to +40°C
Storage temperature: –20°C to +50°C
Humidity
Operating humidity: 5% to 95% RH

U8655
Maintenance Manual
2 Applicable Scope and Precautions
Issue 1.0 (2012-02-23)
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2 Applicable Scope and Precautions
2.1 Applicable Scope
This document provides repair instructions for technicians at service centers authorized by
Huawei. This maintenance manual is confidential and accessible to authorized service centers
(ASCs) and authorized service providers (ASPs) only. While every effort has been made to
ensure the accuracy of this document, errors may still exist. If you find any errors or have any
suggestions, please contact Huawei’s customer service.
2.2 Precautions
Only qualified technicians are allowed to perform repair and calibration.
Perform all operations in electrostatic discharge (ESD) rooms and wear ESD wrist straps
throughout the operations.
Ensure that all components, screws and insulators are properly installed after repair and
calibration, and that all cables and wires are installed and connected correctly.
Ensure that the soldering is lead-free and compliant with eco-friendly requirements.
2.3 How to Obtain Product and Repair Information
To obtain description and repair information about Huawei's products, please visit
http://www.huaweidevice.com/worldwide/technicaIndex.do.
ESD is the main cause of damage to electrostatic-sensitive components. Each
ASC must exercise caution to avoid ESD damage and comply with the ESD
protection requirements in this manual.

U8655
Maintenance Manual
3 Exploded View
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3 Exploded View
The components listed in the following table are structural parts of the phone, and cannot be
used as reference when requesting spare parts.
Table 3-1 List of components in the exploded view drawing
No.
Item
Quantity
1
U8655N_Cover A assembly
1
2
Touchscreen panel
1
3
U8655N_Cover B assembly
1
4
U8655N_Battery cover assembly
1
5
U8655N_Volume key
1
1
5

U8655
Maintenance Manual
3 Exploded View
Issue 1.0 (2012-02-23)
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Copyright © Huawei Technologies Co., Ltd.
5
No.
Item
Quantity
6
U8655N_Speaker shielding cover
1
7
U8655N_CPU shielding cover
1
8
U8655N_RTR shielding cover
1
9
U8655N_PA shielding cover
1
10
U8655N_Proximity and illuminance sensor sealing sheath
1
11
U8655N_MIC_sheath
1
12
U8655N_LCD_conductive fabric
2
13
U8655N_Headset insulation film
1
14
U8655N_USB_adhesive film
1
15
Screw M1.4*3.5
1
16
Diversity antenna and Wi-Fi antenna
1
17
Bluetooth antenna
1
18
Main antenna
1
19
LCD
1
20
Power key flexible flat cable (FFC)
1
21
Receiver
1
22
PCBA
1
23
Volume key FFC
1
24
Camera
1
25
Speaker
1
26
Battery
1
27
NFC antenna
1

U8655
Maintenance Manual
4 Components on the PCBA
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4 Components on the PCBA
J1001camera connector
Failure of this component
can cause:
Camera shooting failure.
J1401 SIM card holder
Failure of this component
can cause:
SIM card failure.
J1402 SD card holder
Failure of this component
can cause:
SD card failure.
U601 Flash memory chip
Failure of this component
can cause:
Power-on failure, software
are malfunction.
U401 CPU, MSM7225A
Failure of this component
can cause:
Power-on failure, phone
system crash, RF failure.
U4401 NFC module
Failure of this component
can cause:
NFC function failure.
U3302 power module, PA
Failure of this component
can cause:
W2100MHz transmission
failure.
U902 motor
Failure of this component
can cause:
Vibration failure.
U3304 duplexer
Failure of this component
can cause:
W2100MHz transmission
and reception failure.
U1402 SD card filter
Failure of this component
can cause:
SD card failure.
U1303 voltage regulator
Failure of this component
can cause:
LCD backlight failure.
U6000 Wi-Fi/Bluetooth/FM
3-in-1 chip
Failure of this component
can cause:
WiFi, Bluetooth and FM
failure.
U201 power management
chip, PM8029
Failure of this component
can cause:
Power-on failure.
X301 crystal oscillator
32.768KHz
Failure of this component
can cause:
Power-on failure.
J1605 ZIF connector
Failure of this component
can cause:
Volume key failure.
U1204 accelerator
Failure of this component
can cause:
Accelerator failure.
U3202 RF switch
Failure of this component
can cause:
RF failure.
U3201 RF connector
Failure of this component
can cause:
RF failure.
J1101 headset jack
Failure of this component
can cause:
Headset failure.
J1601 BTB connector
Failure of this component
can cause:
Touchscreen panel failure.
J902 battery connector
Failure of this component
can cause:
Power-on failure.
U4101 GPS LNA
Failure of this component
can cause:
GPS failure.
J11302 BTB connector
Failure of this component
can cause:
Display failure.

U8655
Maintenance Manual
4 Components on the PCBA
Issue 1.0 (2012-02-23)
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U1207 proximity and
illuminance sensor
Failure of this component
can cause:
Proximity and illuminance
detection failure.
U3404 duplexer
Failure of this component
can cause:
W900MHz transmission
and reception failure.
U3501 power module, PA
Failure of this component
can cause:
GSM transmission failure.
J901 IO connector
Failure of this component
can cause:
Charging failure.
data communication failure.
D1200 tricolor indicator
Failure of this component
can cause:
Tricolor indicator failure.
F901 fuse
Failure of this component
can cause:
Charging failure.
U3401 power module, PA
Failure of this component
can cause:
W900MHz transmission
failure.
U901 DCDC control chip
Failure of this component
can cause:
Charging failure.
U3801 WCDMA/GSM
transmission and
reception chip
Failure of this component
can cause:
RF failure.

U8655
Maintenance Manual
5 Software Upgrade
Issue 1.0 (2012-02-23)
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5 Software Upgrade
5.1 Upgrade Preparation
Category
Item
Description
Upgrade
environment
Computer
To copy upgrade software
microSD card
With more than 512 MB free space
Battery
With at least 30% power remaining
Upgrade file
Main upgrade pack
dload/UPDATE.APP
Vendor upgrade pack
vendor_XXX_XXX/UPDATE.APP
Upgrade
method
Using the microSD card
Normal upgrade
Forcible upgrade
5.2 Upgrade Procedure
1. Format the microSD card.
2. Create a folder named dload in the root directory of the microSD card.
3. Copy the upgrade file to the dload folder.
4. Install the microSD card on the phone. Power the phone on, and enter *#*#2846579#*#*
on the idle screen.
5. Select SD Upgrade then Yes to start the upgrade.
6. Before the upgrade, NV items backup is performed (if the phone's NV items has not
been backed up before). Then the phone restarts and the upgrade starts.
7. The upgrade progress is displayed on the LCD.

U8655
Maintenance Manual
5 Software Upgrade
Issue 1.0 (2012-02-23)
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8. After the upgrade is completed, the phone restarts and the NV items are restored.
9. After the main upgrade pack is upgraded, upgrade the vendor upgrade pack using the
same upgrade method.
If the phone cannot be properly powered on, use one of the following two methods to forcibly
upgrade the phone:
Install the battery on the phone (if the screen is jittering, remove the battery and wait for
five seconds before installing the battery again). Press and hold the Volume+ and
Volume–keys, and press the Power key. The phone enters the SD forcible upgrade mode
in which the upgrade process is similar to the normal upgrade.
While the phone has no battery installed, press and hold the Volume+ and Volume–keys,
and connect the charger to the phone.
The phone enters the SD forcible upgrade. This method is recommended. If the forcible
upgrade still fails, use another microSD card and try forcible upgrade again.

U8655
Maintenance Manual
6 Maintenance Tools
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6 Maintenance Tools
Name: constant-temperature hot air blower gun
Usage: to heat components
Name: constant-temperature heat gun
Usage: to heat components
Name: soldering iron
Usage: to solder components
Name: DC regulated power supply
Usage: to supply DC power
Name: soldering table
Usage: to secure the main PCBA

U8655
Maintenance Manual
6 Maintenance Tools
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11
Name: lead-free solder wire
Usage: soldering
Name: digital multimeter
Usage: to measure during repair
Name: toolkit
Usage: to assemble and disassemble components
Name: electric screwdriver
Usage: to fasten and remove screws

U8655
Maintenance Manual
7 Disassembly Procedure
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7 Disassembly Procedure
1. Wear an ESD wrist strap, and ensure that the strap is
grounded properly.
2. Remove the battery cover: Press the upper part of
the battery cover and push it towards the bottom.
3. Remove the battery.
U8655N before disassembly

U8655
Maintenance Manual
7 Disassembly Procedure
Issue 1.0 (2012-02-23)
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4. Remove the six screws from cover B.
5. Use the disassembly tab to release the latch in the
upper right corner.
6. Use the disassembly tab to release the latch in the
upper left corner.
7. Use a cover opener to release the latches between
cover A and cover B.

U8655
Maintenance Manual
7 Disassembly Procedure
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13. Remove the proximity and illuminance sensor
sheath and the microphone sheath.
11. Release the two latches in the PCBA.
10. Disconnect the BTB connector cable between the
touchscreen panel and the LCD.
8. Remove the volume key.
9. Release the volume key FPC.
12. Remove the PCBA.

U8655
Maintenance Manual
7 Disassembly Procedure
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16. Apply a protective film on the LCD.
14. Release the BTB connector, and remove the
camera. Release the ZIF connector, and remove the
volume key FPC.
15. Release the LCD latches, and remove the LCD.
17. Apply a protective film on the inner side of the
touchscreen panel.