LG 42LD520 Service Manual

The LG 42LD520 is a 42-inch LCD television featuring Full HD 1080p resolution, built-in digital and analog tuners, multiple HDMI inputs, USB connectivity, energy saving technology, and advanced picture processing. This service manual provides comprehensive technical information for service technicians including disassembly procedures, circuit diagrams, troubleshooting guides, and replacement parts information.

Product Specifications

Technical specifications and performance characteristics of the LG 42LD520 LCD television.

Safety Precautions

Important safety information for service technicians working on the LG 42LD520 television.

1. Always disconnect AC power before servicing.
2. Use proper ESD protection when handling circuit boards.
3. High voltage components require special handling procedures.
4. Ensure proper reassembly to maintain electrical safety.

WARNING! High voltage present in power supply and inverter circuits. Discharge capacitors before servicing.

Disassembly Instructions

Step-by-step procedures for disassembling the LG 42LD520 television.

1. Remove stand: Lay TV face down on soft surface, remove screws securing stand.
2. Remove rear cover: Remove all screws from rear cabinet, carefully separate rear cover.
3. Access main boards: Disconnect all cables from power supply, main board, and T-con board.
4. Remove LCD panel: Follow special procedures for handling LCD panel to prevent damage.

CAUTION! Handle LCD panel with care to avoid cracking or damaging the glass substrate.

Circuit Diagrams

• Power Supply Circuit: Complete schematic of EAY40429901 power supply board.
• Main Board: Detailed circuit diagram of EAX61722601 main board.
• Inverter Board: Schematic for backlight inverter circuit EAY40431201.
• T-Con Board: Timing controller circuit diagram.
• Audio Circuit: Amplifier and audio processing circuits.
• Input/Output: HDMI, component, and other input circuits.

PCB Layouts

Physical layout diagrams for all printed circuit boards in the LG 42LD520.

Main Board: Component placement and routing for EAX61722601 main board.

Power Supply: Component layout for EAY40429901 power supply board. Inverter Board: Layout for EAY40431201 inverter board. T-Con Board: Component placement for timing controller board.

Troubleshooting Flowcharts

Systematic troubleshooting procedures for common LG 42LD520 problems.

1. No Power: Check AC input, fuse, standby voltage, main power supply.
2. No Picture/Sound: Verify main board operation, check video processing IC.
3. Backlight Issues: Test inverter output, check CCFL/LED connections.
4. Input Problems: Verify signal sources, check input selection circuits.

Tip: Use factory service mode for detailed error code reading and system diagnostics.

Replacement Parts List

Complete list of replaceable components and part numbers for the LG 42LD520.

1. Main Board: EAX61722601 (replacement part number)
2. Power Supply: EAY40429901
3. Inverter Board: EAY40431201
4. T-Con Board: EBT61255401
5. LCD Panel: LC420EUN (SF) (A1)
6. Remote Control: AKB72915207
7. Speakers: AAY41737001 (x2)
8. Buttons: Various part numbers for front panel controls

WARNING! Use only LG authorized replacement parts to ensure safety and performance.

Adjustment Procedures

Factory adjustment and calibration procedures for the LG 42LD520.

Software Update Guide

Procedures for updating firmware and software on the LG 42LD520 television.

CAUTION! Follow update procedures exactly to avoid bricking the television.

Wiring Connections

Detailed wiring diagrams and connection information for all internal cables and connectors.

Test Points & Measurements

Reset: Enter service menu for factory reset options.

Service Support: LG Service Center 1-800-243-0000; www.lg.com