LG CU920 User Manual

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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..................................9
2.4 Current Consumption.............................16
2.5 RSSI BAR ..............................................16
2.6 Battery BAR ...........................................17
2.7 Charging ................................................17
2.8 Sound Pressure Level............................18
3. TECHNICAL BRIEF ........................19
3.1 General Description ...............................19
3.2 GSM Mode.............................................21
3.3 UMTS Mode...........................................25
3.4 LO generation and distribution circuits...28
3.5 Off-chip RF Components .......................29
3.6 Digital Baseband (MSM6281)................46
3.7. Subsystem(MSM6281) .........................48
3.8 Power Block...........................................57
3.9 External memory interface.....................62
3.10 H/W Sub System..................................64
3.11 MAIN Features.....................................80
4. TROUBLE SHOOTING ...................85
4.1 RF Component.......................................85
4.2 Component Description .........................88
4.3 WCDMA RF Signal Path........................89
4.4 GSM RF Signal Path..............................90
4.5 Checking VCTCXO Block ......................91
4.6 Checking Front-End Module Block ........94
4.7 Checking WCDMA Block .......................96
4.8 Checking GSM Block...........................101
4.9 Checking Bluetooth Block....................107
4.10 Power ON Troubleshooting................110
4.11 Charger Troubleshooting ...................112
4.12 USB Troubleshooting.........................115
4.13 USIM Detect Troubleshooting............117
4.14 Camera Troubleshooting ...................119
4.15 Keypad Backlight Troubleshooting ....121
4.16 LCD Troubleshooting.........................122
4.17 Receiver Path ....................................123
4.18 Headset path......................................125
4.19 Speaker phone path...........................127
4.20 Main microphone ...............................129
4.21 Headset microphone..........................131
4.22 Vibrator ..............................................133
4.23 Checking Media FLO Block ...............134
5. DOWNLOAD .................................138
5.1 Introduction ..........................................138
5.2 Downloading Procedure.......................138
5.3 Troubleshooting download errors ........152
5.4 Caution.................................................159
6. BLOCK DIAGRAM ........................160
7. Circuit Diagram ............................171
8. BGM Pin Map................................181
9. PCB LAYOUT................................183
10. Calibration & RF Auto Test
Program (Hot Kimchi)................187
10.1 Configuration of HOT KIMCHI ...........187
10.2 How to use HOT KIMCHI...................188
11. EXPLODED VIEW &
REPLACEMENT PART LIST ..... 191
11.1 EXPLODED VIEW ............................ 191
11.2 Replacement Parts
<Mechanic component>.................... 193
<Main component> ........................... 195
11.3 Accessory ......................................... 212
Table Of Contents
LGE Internal Use Only Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes

LG CU920 Specifications

Camera

camera resolution	1600x1200, 1280x960, 640x480, 320x240, 160x120 Pixels
video resolution	320x240, 176x144 Pixels
zoom	Up to 2x

Power

standard battery	1, 000 mAh Li-Ion
talk time	Up to 3 Hours
standby time	Up to 10 Days & 10 Hours

Memory and Storage

internal memory	120MB
microSD memory port	Yes
USB mass storage	Yes

Weight and Dimensions

dimensions	4.25” (H) x 2.16” (W) x 0.51” (D)
weight	3.16 oz.
display size	3.00”

Summary

Device Performance Specifications

Radio Performance: GSM Transmitter

Presents transmitter performance data for GSM modes, including output power.

Radio Performance: WCDMA Transmitter

Details WCDMA transmitter specifications like output power and frequency error.

Radio Performance: GSM Receiver

Specifies GSM receiver performance: sensitivity, rejection, and intermodulation.

Radio Performance: WCDMA Receiver

Details WCDMA receiver specs: sensitivity, blocking, and spurious emissions.

Technical Brief: System Architecture

General System Description and RF Paths

GSM Mode: Receiver and Antenna Switching

UMTS Mode: Receiver and Transmitter Operations

Off-chip RF Components: UMTS Duplexer

Off-chip RF Components: WCDMA Power Amplifier

GSM Power Amplifier Module (SKY77329)

Digital Baseband: MSM6281 Features

Digital Baseband: MSM6281 Subsystems

Power Block Overview

Power Management IC (PM6650) Functions

Battery Charging Control Mechanisms

External Memory Interface Details

Hardware Subsystem: RF Interface Signals

Audio Signal Processing Overview

CU920/CU915 Main Features Summary

Troubleshooting Guide for Phone Functions

RF Component Identification

Identifies RF component locations on the PCB.

Description of Key Phone Components

Lists common, Bluetooth, WCDMA/GSM, WCDMA, GSM, and Bluetooth components.

WCDMA RF Signal Path Analysis

Details the WCDMA RF signal path for Tx and Rx.

GSM RF Signal Path Analysis

Details the GSM RF signal path for Tx and Rx.

VCTCXO Block Troubleshooting Guide

Guides checking the VCTCXO block for reference frequency.

Front-End Module (FEM) Troubleshooting

Guides checking the Front-End Module block.

WCDMA Block Troubleshooting Steps

Guides checking the WCDMA block.

WCDMA PAM Control Block Verification

Guides checking WCDMA PAM control signals.

WCDMA Receiver Level Check

Guides checking WCDMA receiver level.

GSM Block Troubleshooting Steps

Guides checking the GSM block.

GSM PAM Block Verification

Guides checking the GSM PAM block and its control signals.

GSM Receiver Block Troubleshooting

Guides checking the GSM RX block.

Bluetooth Block Troubleshooting Steps

Guides checking the Bluetooth block.

Power ON Sequence Troubleshooting

Guides troubleshooting power-on issues.

Charger Troubleshooting Procedures

Guides troubleshooting charger-related issues.

USB Connection and Functionality Troubleshooting

Guides troubleshooting USB connection and functionality.

USIM Card Detection Troubleshooting

Guides troubleshooting USIM detection issues.

Camera Module Troubleshooting Steps

Guides troubleshooting camera issues.

Keypad Backlight Troubleshooting Guide

Guides troubleshooting keypad backlight issues.

LCD Display Troubleshooting Steps

Guides troubleshooting LCD issues.

Receiver Path Audio Output Troubleshooting

Guides troubleshooting the receiver path.

Headset Path Audio Output Troubleshooting

Guides troubleshooting the headset path.

Speaker Phone Audio Path Troubleshooting

Guides troubleshooting the speaker phone path.

Main Microphone Functionality Check

Guides troubleshooting the main microphone.

Headset Microphone Path Troubleshooting

Guides troubleshooting the headset microphone.

Vibrator Operation and Troubleshooting

Guides troubleshooting the vibrator.

Media FLO Block Troubleshooting Guide

Guides checking the Media FLO block.

Software Download Procedures

Step-by-Step Downloading Process

Guides the procedure for downloading images to the handset.

Connecting the Handset to the PC

Explains how to connect the phone to the PC using LGMDP.

Selecting Image Files for Download

NV Backup and Restore Procedures

Download Process Overview and Steps

Download Error Troubleshooting: NV Restore

Guides troubleshooting NV Restore errors.

Download Process Cautions and Recommendations

System Block Diagrams

Overall Phone Block Diagram

Circuit Diagrams and Schematics

RF Circuit Diagram Overview

Calibration and RF Auto Test Program (Hot Kimchi)

Using the HOT KIMCHI Software

Exploded View and Replacement Parts List