LG 42LE5400 Service Manual

The LG 42LE5400 is a 42-inch LED TV with Full HD 1080p resolution, built-in digital tuner, multiple HDMI inputs, USB connectivity, Smart TV features, energy saving technology, and advanced picture processing. This service manual provides technical information for qualified service personnel including disassembly instructions, circuit diagrams, troubleshooting procedures, and replacement parts information.

Product Overview

The LG 42LE5400 features LED edge-lit technology with local dimming, 120Hz refresh rate, and LG's INFINIA design. Key components include main board, power supply board, T-CON board, LED driver board, and LCD panel assembly.

Technical Specifications

• Screen Size: 42 inches LED LCD
• Resolution: 1920 x 1080 Full HD
• Refresh Rate: 120Hz
• Brightness: 400 cd/m²
• Contrast Ratio: 5,000,000:1 (Dynamic)
• Inputs: 4x HDMI, 2x USB, Component, Composite, RF
• Power Consumption: 85W typical, <1W standby
• Power Supply: 100-240V AC, 50/60Hz
• Dimensions: 38.7" x 25.2" x 1.5" (without stand)
• Weight: 28.7 lbs (without stand)

Disassembly Instructions

Follow these steps to safely disassemble the TV 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 cover.
3. Disconnect cables: Note cable positions before disconnecting from boards.
4. Remove shield plates: Unscrew metal shields protecting circuit boards.
5. Access individual boards: Remove screws securing each board for replacement.

WARNING! Discharge capacitors before handling power supply. Use anti-static precautions.

Circuit Diagrams

Complete schematic diagrams for all major circuits:

• Main Board Schematic - Pages 15-22
• Power Supply Schematic - Pages 23-28
• T-CON Board Schematic - Pages 29-31
• LED Driver Schematic - Pages 32-34
• Input/Output Section - Pages 35-38

Note: All voltages measured with respect to chassis ground unless specified.

Main Board Replacement

Procedure for replacing main board EAX61743001:

1. Disconnect power and remove rear cover.
2. Remove screws securing main board shield.
3. Carefully disconnect all cables and connectors.
4. Remove mounting screws and extract old board.
5. Install new board and reconnect all cables.
6. Reassemble and test all functions.

CAUTION! Handle board by edges only. Ensure proper cable orientation.

Power Supply Board

Power supply board EAY62836601 provides these voltages:

Test Points: TP1 (GND), TP2 (+5V), TP3 (+12V), TP4 (+24V)

LCD Panel Service

LC420EUN panel specifications and service notes:

• Panel Type: IPS (In-Plane Switching)
• Response Time: 5ms gray-to-gray
• Viewing Angle: 178°/178°
• Backlight: White LED edge-lit
• Interface: LVDS 8-bit dual port

WARNING! LCD panel is fragile. Handle with extreme care to avoid damage.

Backlight System

LED backlight system consists of 4 LED strips with 18 LEDs each:

1. Top strip: 18 white LEDs
2. Bottom strip: 18 white LEDs
3. Left strip: 18 white LEDs
4. Right strip: 18 white LEDs

LED Driver Board: EAX61743501 controls brightness and provides over-current protection.

Note: Individual LED strips can be replaced if faulty.

Troubleshooting Guide

Parts List

Key replacement parts for LG 42LE5400:

Safety Precautions

Essential safety guidelines for service personnel:

1. Always disconnect AC power before servicing
2. Discharge high-voltage capacitors before handling
3. Use insulated tools when working with live circuits
4. Wear anti-static wrist strap when handling boards
5. Ensure proper reassembly to maintain safety certifications

WARNING! High voltages present even when power is disconnected. Exercise extreme caution.

Service Support: LG Service Center 1-800-243-0000