LG U370, Service Manual, Page: 2 / 179

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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.................................14
2.5 RSSI BAR ..................................................14
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 ......25
3.5 Off-chip RF Components ...........................25
3.6 Digital Baseband(DBB/MSM6245) ............34
3.7 Subsystem(MSM6245) ..............................37
3.8 Power Block...............................................45
3.9 External memory interface.........................50
3.10 H/W Sub System .....................................52
3.11 Main Features..........................................66
4. TROUBLE SHOOTING.......................71
4.1 RF Component ..........................................71
4.2 SIGNAL PATH_UMTS RF .........................74
4.3 SIGNAL PATH_GSM RF ...........................75
4.4 Checking VC-TCXO Block.........................76
4.5 Checking Front-End Module Block ............78
4.6 Checking UMTS Block...............................80
4.7 Checking Bluetooth Block..........................85
4.8 Power ON Troubleshooting .......................87
4.9 Charger Troubleshooting ...........................90
4.10 USB Troubleshooting...............................92
4.11 SIM Detect Troubleshooting ....................93
4.12 Camera Troubleshooting .........................96
4.13 LCD module Troubleshooting ..................99
4.14 Receiver Path ........................................101
4.15 Headset path .........................................103
4.16 Speaker phone path ..............................105
4.17 Main microphone ...................................107
4.18 Headset microphone..............................109
5. DOWNLOAD .....................................111
5.1 Introduction ..............................................111
5.2 Downloading Procedure ..........................111
5.3 Troubleshooting Download Errors ..........124
5.4 Caution ....................................................129
6. BLOCK DIAGRAM ...........................130
6.1 GSM & UMTS RF Block ..........................130
6.2 Interface Diagram ....................................132
7. CIRCUIT DIAGRAM..........................139
8. BGA IC PIN MAP..............................145
9. PCB LAYOUT ...................................149
10. Calibration & RF Auto Test Program
(Hot Kimchi) ...................................155
10.1 Configuration of HOT KIMCHI ...............155
10.2 How to use HOT KIMCHI.......................158
11. EXPLODED VIEW & REPLACEMENT
PART LIST ..................................... 161
11.1 EXPLODED VIEW ................................ 161
11.2 Replacement Parts
<Mechanic component> ....................... 163
<Main component> ............................... 165
11.3 Accessory ............................................. 178
Table Of Contents
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