LG G3 D855 Full Service Manual Schematics

The LG G3 D855 is a flagship smartphone featuring a 5.5-inch Quad HD IPS LCD display, Qualcomm Snapdragon 801 processor, 13MP OIS+ camera with laser autofocus, 2GB/3GB RAM variants, 16GB/32GB storage options, removable 3000mAh battery, and Android 4.4.2 KitKat (upgradable). Below are comprehensive sections covering disassembly, repair procedures, schematics, troubleshooting, and technical specifications for service technicians.

1. Device Overview 2. Disassembly Procedure 3. Component Schematics 4. Technical Specifications 5. Board Layout & Connectors 6. Power Management 7. Display Assembly 8. Camera Module 9. Battery Replacement 10. Troubleshooting Guide 11. Safety Precautions

Device Overview

Key components: Main board with Snapdragon 801 MSM8974AC, display assembly, camera module, battery, and various connectors.

Component	Description
Main Board	Qualcomm MSM8974AC, PM8941 power management, WCD9320 audio codec
Display Assembly	5.5-inch IPS LCD, 2560x1440 resolution, Gorilla Glass 3
Camera Module	13MP OIS+ with laser autofocus, 2.1MP front camera
Battery	Removable 3000mAh Li-Polymer (BL-53YH)
Connectors	Display flex, camera flex, power/volume flex, speaker flex
Wireless	Wi-Fi 802.11ac, Bluetooth 4.0, NFC, IR blaster
Sensors	Accelerometer, gyroscope, proximity, ambient light
Ports	Micro USB 2.0, 3.5mm audio jack

Disassembly Procedure

Required tools: Plastic opening tools, T4/T5 Torx screwdrivers, spudger, tweezers.

Power off device and remove back cover
Remove battery from compartment
Remove 12 T5 screws from rear frame
Carefully separate mid-frame from display assembly
Disconnect display flex cable and remove display
Remove motherboard securing screws and lift board
Disconnect all flex cables from main board
Remove camera modules and other components

WARNING! Use proper ESD protection. Handle display assembly carefully to avoid damage.

Component Schematics

Detailed circuit diagrams for main board sections:

Power Management: PM8941 block diagram with voltage rails
Processor Section: MSM8974AC pinout and connections
Memory Interface: LPDDR3 RAM and eMMC flash connections
Audio Circuit: WCD9320 codec with amplifier circuits
RF Section: Cellular, Wi-Fi, and Bluetooth radio circuits
Sensor Hub: Accelerometer, gyroscope, and other sensors
Camera Interface: Main and front camera connections
Display Circuit: MIPI DSI interface and backlight driver

Technical Specifications

Model: LG G3 D855 (International)
Display: 5.5-inch True HD-IPS+ LCD, 2560x1440, 538ppi
Chipset: Qualcomm Snapdragon 801 (MSM8974AC)
CPU: Quad-core 2.5 GHz Krait 400
GPU: Adreno 330
Memory: 2GB/3GB RAM, 16GB/32GB internal storage
Camera: 13MP rear with OIS+, laser AF; 2.1MP front
Battery: Removable 3000mAh Li-Polymer
OS: Android 4.4.2 KitKat (upgradable to 6.0 Marshmallow)
Connectivity: LTE Cat4, Wi-Fi 802.11ac, Bluetooth 4.0, NFC
Dimensions: 146.3 x 74.6 x 8.9 mm
Weight: 149g

Board Layout & Connectors

Main board component locations and connector pinouts:

Connector	Type	Pin Count	Function
J1001	FPC	40-pin	Display Assembly
J2001	FPC	30-pin	Main Camera Module
J3001	FPC	20-pin	Front Camera
J4001	FPC	24-pin	Power/Volume Flex
J5001	FPC	16-pin	Speaker Assembly
J6001	Board-to-Board	50-pin	Sub Board Connection
J7001	Coaxial	-	Main Antenna
J8001	Coaxial	-	Wi-Fi/BT Antenna

Power Management

PM8941 power management IC with multiple voltage regulators:

Main Power Input: Battery voltage regulation and distribution
Core Voltages: VDD_APC, VDD_CX, VDD_MX for processor
Memory Power: LPDDR3 and eMMC voltage rails
Display Power: Backlight driver and panel power
Audio Power: Codec and amplifier power supplies
Camera Power: Dedicated power for camera modules
Charging Circuit: Battery charging management

CAUTION! Verify all voltage rails before powering on repaired device.

Display Assembly

5.5-inch Quad HD IPS LCD display replacement procedure:

Remove damaged display from frame
Clean frame adhesive residue
Apply new adhesive to frame
Align and install new display assembly
Connect display flex cable to main board
Test display before final assembly
Reassemble device and secure all screws

WARNING! Handle display with care - glass is fragile and expensive to replace.

Camera Module

13MP OIS+ camera with laser autofocus system:

Main Camera: 13MP sensor, f/2.4 aperture, OIS+
Laser AF: Infrared laser distance measurement
Front Camera: 2.1MP sensor for video calls
Replacement: Remove rear cover, disconnect flex, install new module
Testing: Verify focus, OIS, and image quality after replacement

Battery Replacement

BL-53YH 3000mAh Li-Polymer battery replacement:

Power off device completely
Remove back cover carefully
Lift battery from compartment using adhesive tab
Disconnect battery connector from main board
Install new battery and connect connector
Replace back cover and power on
Calibrate battery by full charge/discharge cycle

CAUTION! Use only genuine LG batteries. Do not puncture or damage battery.

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No Power	Battery/charging circuit	Check battery voltage; test charging port; verify PMIC
No Display	Display/backlight circuit	Test display connector; check backlight voltage; replace display
Camera Not Working	Camera module/connector	Reseat camera flex; test camera power; replace module
No Network	RF circuit/antenna	Check antenna connections; test RF components; reflow/baseband
Overheating	Processor/power management	Check thermal paste; test voltage regulators; replace PMIC
Audio Issues	Speaker/codec circuit	Test speaker continuity; check audio codec; replace speaker
Touchscreen Issues	Digitizer/connector	Reseat display flex; test touch controller; replace digitizer

Safety Precautions

Essential safety measures for service technicians:

Always use ESD wrist strap when handling components
Disconnect battery before performing any repairs
Use proper tools to avoid damage to components
Work in clean, well-lit environment
Follow proper disposal procedures for damaged batteries
Test all functions thoroughly before returning device
Keep work area free of liquids and contaminants

WARNING! Lithium batteries can be hazardous if damaged - handle with care.