LG CU720 Black User manual

Date: November, 2007 / Issue 1.0
Service Manual Model : CU720
Service Manual
CU720
Internal Use Only
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1. INTRODUCTION.................................. 5
1.1 Purpose ...................................................... 5
1.2 Regulatory Information ............................... 5
2. PERFORMANCE ..................................7
2.1 System Overview.........................................7
2.2 Usable environment.....................................8
2.3 Radio Performance......................................8
2.4 Current Consumption.................................15
2.5 RSSI BAR ..................................................15
2.6 Battery BAR ...............................................15
2.7 Sound Pressure Level ...............................16
2.8 Charging ....................................................16
3. TECHNICAL BRIEF............................17
3.1 General Description ...................................17
3.2 GSM Mode.................................................19
3.3 UMTS Mode...............................................23
3.4 LO generation and distribution circuits ......26
3.5 Off-chip RF Components ...........................26
3.6 Digital Baseband (MSM6280)....................38
3.7 Subsystem(MSM6280) ..............................40
3.8 Power Block...............................................48
3.9. External memory interface........................53
3.10 H/W Sub System .....................................55
3.11. MAIN Features........................................74
4. TROUBLE SHOOTING.......................79
4.1 RF Component ..........................................79
4.2 Component Description .............................80
4.3 WCDMA RF Signal Path............................81
4.4 GSM RF Signal Path .................................82
4.5 Checking VCTCXO Block ..........................83
4.6 Checking Front-End Module Block ............85
4.7 Checking WCDMA Block ...........................87
4.8 Checking GSM Block.................................92
4.9 Checking Bluetooth Block..........................98
4.10 Power ON Troubleshooting ...................101
4.11 Charger Troubleshooting .......................103
4.12 USB Troubleshooting.............................106
4.13 USIM Detect Troubleshooting................108
4.14 Camera Troubleshooting .......................110
4.15 Keypad Backlight Troubleshooting ........113
4.16 Folder ON/OFF Troubleshooting ...........115
4.17 Main LCD Troubleshooting ....................116
4.18 Receiver Path ........................................117
4.19 Headset path .........................................119
4.20 Speaker phone path ..............................121
4.21 Main microphone ...................................123
4.22 Headset microphone..............................125
4.23 Vibrator ..................................................127
5. DOWNLOAD.....................................128
5.1 Introduction ..............................................128
5.2 Downloading Procedure ..........................128
5.3 Troubleshooting download errors ............141
5.4 Caution ....................................................149
6. BLOCK DIAGRAM ...........................150
6.1 GSM & UMTS RF Block ..........................150
6.2 Interface Diagram ....................................152
7. CIRCUIT DIAGRAM..........................159
8. BGA IC PIN MAP..............................169
9. PCB LAYOUT ...................................171
10. Calibration & RF Auto
Test Program (Hot Kimchi) ...........177
10.1 Configuration of HOT KIMCHI ...............177
10.2 How to use HOT KIMCHI.......................179
11. EXPLODED VIEW & REPLACEMENT
PART LIST ..................................... 181
11.1 EXPLODED VIEW ................................ 181
11.2 Replacement Parts
<Mechanic component> ....................... 183
<Main component> ............................... 186
11.3 Accessory ............................................. 203
Table Of Contents
LGE Internal Use Only Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Z3X-BOX.COM

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LGE Internal Use Only Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Z3X-BOX.COM

LGE Internal Use Only Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
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1.1 Purpose
This manual provides the information necessary to repair, calibration, description and download the
features of this model.
1.2 Regulatory Information
A. Security
Toll fraud, the unauthorized use of telecommunications system by an unauthorized part (for example,
persons other than your company’s employees, agents, subcontractors, or person working on your
company’s behalf) can result in substantial additional charges for your telecommunications services.
System users are responsible for the security of own system.
There are may be risks of toll fraud associated with your telecommunications system. System users
are responsible for programming and configuring the equipment to prevent unauthorized use. The
manufacturer does not warrant that this product is immune from the above case but will prevent
unauthorized use of commoncarrier telecommunication service of facilities accessed through or
connected to it. The manufacturer will not be responsible for any charges that result from such
unauthorized use.
B. Incidence of Harm
If a telephone company determines that the equipment provided to customer is faulty and possibly
causing harm or interruption in service to the telephone network, it should disconnect telephone
service until repair can be done. A telephone company may temporarily disconnect service as long as
repair is not done.
C. Changes in Service
A local telephone company may make changes in its communications facilities or procedure. If these
changes could reasonably be expected to affect the use of the phones or compatibility with the net
work, the telephone company is required to give advanced written notice to the user, allowing the user
to take appropriate steps to maintain telephone service.
D. Maintenance Limitations
Maintenance limitations on the phones must be performed only by the manufacturer or its authorized
agent. The user may not make any changes and/or repairs expect as specifically noted in this manual.
Therefore, note that unauthorized alternations or repair may affect the regulatory status of the system
and may void any remaining warranty.
1. INTRODUCTION
1. INTRODUCTION
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LGE Internal Use Only Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
E. Notice of Radiated Emissions
This model complies with rules regarding radiation and radio frequency emission as defined by local
regulatory agencies. In accordance with these agencies, you may be required to provide information
such as the following to the end user.
F. Pictures
The pictures in this manual are for illustrative purposes only; your actual hardware may look slightly
different.
G. Interference and Attenuation
A phone may interfere with sensitive laboratory equipment, medical equipment, etc. Interference from
unsuppressed engines or electric motors may cause problems.
H. Electrostatic Sensitive Devices
ATTENTION
Boards, which contain Electrostatic Sensitive Device (ESD), are indicated by the sign.
Following information is ESD handling:
• Service personnel should ground themselves by using a wrist strap when exchange system boards.
• When repairs are made to a system board, they should spread the floor with anti-static mat which is
also grounded.
• Use a suitable, grounded soldering iron.
• Keep sensitive parts in these protective packages until these are used.
• When returning system boards or parts like EEPROM to the factory, use the protective package as
described.
1. INTRODUCTION
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