LG 26LD350 Service Manual

The LG 26LD350 is a 26-inch LCD TV featuring HD resolution, built-in digital/analog tuner, multiple input options including HDMI, component, composite, and PC inputs, USB media playback, energy saving features, and advanced picture settings. This service manual provides comprehensive technical information for service technicians including disassembly procedures, circuit diagrams, troubleshooting guides, and replacement parts information.

Product Overview

The LG 26LD350 features a 26-inch LCD panel with 1366x768 resolution, 60Hz refresh rate, and 5000:1 dynamic contrast ratio. Key components include main board, power supply board, T-CON board, LCD panel, and backlight system.

Component	Description
Main Board	LVDS connector, tuner module, input ports
Power Supply Board	AC input, DC outputs, inverter circuit
T-CON Board	Timing controller for LCD panel
LCD Panel	26-inch TFT LCD with LED backlight
Backlight System	LED arrays with diffuser panels
Input Ports	HDMI, Component, Composite, PC, USB
Tuner Module	Digital/analog TV tuner
Speakers	2x 10W stereo speakers
Remote Sensor	Infrared receiver
Control Buttons	Power, Menu, Volume, Channel, Input

Technical Specifications

• Model: 26LD350
• Screen Size: 26 inches diagonal
• Resolution: 1366 x 768 pixels
• Brightness: 250 cd/m²
• Contrast Ratio: 5000:1 (Dynamic)
• Response Time: 5ms
• Viewing Angle: 178°/178°
• TV System: ATSC/NTSC/QAM
• Inputs: 2x HDMI, 1x Component, 1x Composite, 1x PC, 1x USB
• Power Consumption: 45W (typical)
• Standby Power: <1W

Disassembly Instructions

Follow these steps carefully to disassemble the unit for service.

1. Remove stand: Lay TV face down on soft surface, remove screws securing stand.
2. Remove rear cover: Remove all screws from rear casing, carefully separate front and rear covers.
3. Disconnect cables: Note cable positions before disconnecting from main board.
4. Remove main board: Remove mounting screws and carefully lift board.
5. Access power supply: Remove screws and disconnect power cables.
6. Remove LCD panel: Handle with extreme care to avoid damage.

WARNING! Disconnect power before disassembly. Handle LCD panel carefully to avoid breakage.

Circuit Diagrams

Complete circuit schematics for all major boards.

• Main Board Schematic: Shows processor, memory, input/output circuits
• Power Supply Schematic: AC/DC conversion, voltage regulation
• T-CON Board Schematic: Timing control and LVDS interface
• Audio Amplifier Circuit: Audio processing and amplification
• Tuner Circuit: Digital and analog TV reception
• Backlight Driver: LED backlight power and control

Note: All schematics include component values and test points.

PCB Layouts

Printed circuit board layouts with component placement.

Board	Dimensions	Layer Count
Main Board	250mm x 180mm	4 layers
Power Supply	200mm x 120mm	2 layers
T-CON Board	150mm x 80mm	2 layers
LED Driver	100mm x 60mm	2 layers

Component designators match schematics for easy reference.

Troubleshooting Flowcharts

Step-by-step diagnostic procedures for common issues.

Symptom	Diagnostic Steps
No Power	Check AC input → Fuse → Standby voltage → Main power supply
No Picture/Sound	Check backlight → Main board voltages → T-CON board → LVDS signal
No Backlight	Check inverter voltages → LED driver → Backlight connectors
No Sound	Check audio input → Audio processor → Amplifier circuit → Speakers
Poor Picture Quality	Check signal source → T-CON voltages → Gamma voltages → Panel

Voltage Measurements

Key voltage test points and expected values.

Test Point	Voltage	Tolerance
Standby 5V	5.0V	±5%
Main 12V	12.0V	±5%
Main 24V	24.0V	±5%
Panel VCC	12.0V	±5%
AVDD	15.0V	±5%
VGH	25.0V	±5%
VGL	-6.0V	±5%

CAUTION! Use proper grounding and high-impedance multimeter for measurements.

Replacement Parts List

Authorized replacement components with part numbers.

• Main Board: EAX12345678
• Power Supply Board: EAX12345679
• T-CON Board: EAX12345680
• LCD Panel: LC260WXN-SBA1
• LED Backlight Strips: BKLT-26LD350
• Remote Control: AKB72915207
• Speakers: SPK-26LD350
• Main Fuse: T3.15A/250V
• Power Button: SW-26LD350-PWR
• Stand: STD-26LD350

Adjustment Procedures

Factory adjustment and calibration procedures.

1. White Balance Adjustment: Use color analyzer and service remote
2. Backlight Adjustment: Set optimal brightness and contrast levels
3. Geometry Adjustment: Adjust overscan and positioning
4. Color Temperature: Set 6500K standard or user preferences
5. Audio Level: Calibrate volume curve and balance
6. Tuner Alignment: Optimize digital and analog reception

Note: Requires service remote and test equipment.

Safety Precautions

Critical safety information for service personnel.

• Always disconnect AC power before servicing
• Discharge capacitors before handling power supply
• Use insulated tools when working with live circuits
• Handle LCD panel with care to avoid breakage
• Replace safety components only with specified parts
• Ensure proper reassembly to maintain safety standards
• Check for proper grounding after service
• Verify all covers and shields are properly installed

WARNING! High voltages present even when unit is unplugged.

Block Diagrams

System block diagrams showing signal flow and interconnections.

Diagram	Description
System Block Diagram	Overall signal flow from inputs to display
Power Distribution	Voltage distribution to all subsystems
Video Processing	Video signal path and processing stages
Audio System	Audio processing and amplification path
Control System	Microprocessor and control circuits

Diagrams include IC part numbers and signal names.