LG B2050, Service Manual

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Table Of Contents
1. INTRODUCTION ..........................2
1.1 Purpose ...........................................2
1.2 Regulatory Information ....................2
1.3 Abbreviations ..................................4
2. PERFORMANCE ........................ 6
2.1 H/W Feature ...................................6
2.2 Technical Specification ..................8
3. TECHNICAL BRIEF ..................13
3.1 Transceiver ...................................13
3.2 Power Amplifier Module ..................19
3.3 13 MHz Clock ............................... 20
3.4 Power Supplies of RF circuits ........20
Digital Main Processor..................22
3.6 Analog Main & Power
Management Processor ................28
3.7 Display Interface ............................. 38
3.8 Keypad Switches and Scanning .... 41
3.9 Microphone ....................................42
3.10 Main Speaker ............................. 42
3.11 Headset interface ........................43
3.12 Key Back-light Illumination .......... 44
3.13 Vibrator ........................................45
4. TROUBLE SHOOTING ............. 46
4.1 RX Trouble ................................... 46
4.2 TX Trouble ................................... 53
4.3 Power On Trouble .........................61
4.4 Charging Trouble ........................... 63
4.5 Vibrator Trouble..............................65
4.6 LCD Trouble .................................. 67
4.7 Speaker Trouble .............................71
4.8 SIM card interface trouble ............ 74
4.9 Earphone Trouble ...........................76
4.10 Key Backlight Trouble ..................78
4.11 Receiver Trouble...........................80
4.12 Microphone Trouble .................... 82
4.13 RTC Trouble .................................84
4.14 Indication LED Trouble..................86
5. DOWNLOAD AND
CALIBRATION .......................88
5.1 Download .......................................88
5.2 Calibration .......................................93
6. BLOCK DIAGRAM .....................94
7. CIRCUIT DIAGRAM ...................97
8. PCB LAYOUT .........................102
9. ENGINEERING MODE .............105
9.1 BB Test [MENU 1] .........................106
9.2 RF Test [MENU 2] .........................107
9.3 MF mode [MENU 3] ......................108
9.4 Trace option [MENU 4] ..................109
9.5 Call timer [MENU 5] ......................109
9.6 Fact. Reset [MENU 6] ...................109
9.7 S/W version [MENU 7] ..................109
10. STAND ALONE TEST.............110
10.1 Introduction ...............................110
10.2 Setting Method............................110
10.3 Means of Test ............................111
12. AUTO CALIBRATION ...........113
11.1 Overview.....................................113
11.2 Requirements ..............................113
11.3 Menu and Settings ......................113
11.4 AGC............................................115
11.5 APC ............................................115
11.6 ADC ............................................115
11.7 Setting ........................................115
11.8 How to do calibration...................115
12. EXPLODED VIEW &
REPLACEMENT PART LIST ...117
12.1 Exploded View ............................117
12.2 Replacement Parts
<Mechanic component> ...............119
<Main component>......................120
12.3 Accessory ....................................130