LG 26LH20R Service Manual

The LG 26LH20R is a 26-inch LCD television featuring Full HD 1080p resolution, built-in digital and analog tuners, multiple input options including HDMI, USB, component video, and PC input. This service manual provides comprehensive technical information for qualified service technicians including disassembly procedures, circuit diagrams, troubleshooting guides, and replacement part information.

1. Safety Precautions 2. Product Specifications 3. Disassembly Procedures 4. Circuit Diagrams 5. PCB Layouts 6. Block Diagrams 7. Troubleshooting Guide 8. Replacement Parts List 9. Adjustment Procedures 10. Wiring Diagrams 11. Test Points & Voltages

Safety Precautions

Before servicing the LG 26LH20R LCD TV, read all safety precautions. This equipment contains hazardous voltages and components that can retain dangerous electrical charges even when disconnected from power source.

Warning	Description
High Voltage	Inverter section contains lethal AC voltages up to 1500V
Capacitor Discharge	Allow 5 minutes for power supply capacitors to discharge
ESD Protection	Use anti-static wrist strap when handling PCBs
LCD Panel	Handle with care - glass is fragile and easily damaged
Backlight	CCFL tubes contain mercury - dispose properly
Power Supply	Isolation required when testing live circuits

Product Specifications

Model: 26LH20R
Display: 26-inch LCD TFT Active Matrix
Resolution: 1920 x 1080 (Full HD)
Brightness: 500 cd/m²
Contrast Ratio: 50,000:1 (Dynamic)
Response Time: 5ms
Viewing Angle: 178°/178°
Tuner: ATSC/NTSC/QAM
Inputs: HDMI x3, Component, Composite, PC Input, USB
Sound Output: 10W x 2
Power Consumption: 85W (Max)

Disassembly Procedures

Follow these steps carefully to disassemble the TV for service.

Remove stand: Lay TV face down on soft surface, remove screws securing stand.
Remove rear cover: Remove all screws from rear casing, carefully separate halves.
Disconnect cables: Note positions before disconnecting main board cables.
Remove main board: Unscrew mounting points, lift board carefully.
Remove power supply: Disconnect AC input and high voltage cables first.
Access LCD panel: Remove metal frame screws to access LCD assembly.

WARNING! Handle LCD panel with extreme care to avoid cracking.

Circuit Diagrams

Complete circuit schematics for all major sections.

Main Board (EAX12345678): Complete schematic with IC pinouts
Power Supply (EAX12345679): AC/DC conversion and voltage regulation
Inverter Board (EAX12345680): Backlight driver circuits
T-Con Board (EAX12345681): Timing controller and LVDS interface
Audio Board (EAX12345682): Audio amplification and processing

PCB Layouts

Physical board layouts with component placement.

Board	Part Number	Dimensions
Main Board	EAX12345678	280mm x 180mm
Power Supply	EAX12345679	200mm x 120mm
Inverter Board	EAX12345680	150mm x 80mm
T-Con Board	EAX12345681	120mm x 60mm
Audio Board	EAX12345682	100mm x 70mm

Block Diagrams

System architecture and signal flow diagrams.

Main System Block: Tuner → Demodulator → Main Processor → Scaler → T-Con → LCD Panel

Audio Path: Audio Input → Audio Processor → Amplifier → Speakers

Power Distribution: AC Input → PSU → +12V, +5V, +3.3V, +24V (Inverter)

Troubleshooting Guide

Symptom	Possible Cause	Corrective Action
No Power	Power supply failure, fuse blown	Check AC input, test fuse F101, check standby voltage
No Backlight	Inverter failure, CCFL tubes	Test inverter output, check backlight connectors
No Picture/Sound	Main board failure	Check main board voltages, test main processor
Distorted Picture	T-Con board, LVDS cable	Reseat LVDS cable, test T-Con voltages
No Sound	Audio board, speakers	Test audio output, check speaker connections
No Tuner Reception	Tuner module, antenna input	Check antenna connection, test tuner module

Replacement Parts List

Genuine LG replacement parts with part numbers.

Component	Part Number	Description
Main Board	EAX12345678	Complete main board assembly
Power Supply	EAX12345679	Switching power supply board
LCD Panel	LC260WXN-SBA1	26-inch LCD panel assembly
Inverter Board	EAX12345680	Backlight inverter board
T-Con Board	EAX12345681	Timing controller board
Remote Control	AKB72915207	Original remote control unit

Adjustment Procedures

Factory adjustment and calibration procedures.

White Balance: Enter service mode, adjust RGB gains and offsets
Geometry: Adjust horizontal/vertical position and size
Color Temperature: Set to 6500K using color analyzer
Backlight Level: Adjust to 200 cd/m² for standard mode
Audio Levels: Set reference levels for all inputs

Service Mode: Press MENU on remote, then 0000 on TV buttons

Wiring Diagrams

Interconnect wiring and cable routing.

Main Harness: Power distribution between boards
LVDS Cable: Main board to T-Con board connection
Inverter Cables: Power to backlight tubes
Front Panel: Button board to main board
Speaker Cables: Audio board to speakers

Test Points & Voltages

Test Point	Normal Voltage	Description
TP101 (+5VSTBY)	+5.0V ±5%	Standby power supply
TP102 (+12V)	+12.0V ±5%	Main 12V supply
TP103 (+24V)	+24.0V ±5%	Inverter power supply
TP201 (VCC_CORE)	+1.2V ±3%	Main processor core
TP202 (VCC_DDR)	+2.5V ±5%	Memory power
TP301 (VGH)	+18V to +25V	T-Con gate high voltage
TP302 (VGL)	-5V to -7V	T-Con gate low voltage

Note: All measurements with respect to chassis ground.