LG 42LH30-UA Service Manual

The LG 42LH30-UA is a 42-inch LCD HDTV featuring 1080p Full HD resolution, built-in digital/analog tuner, multiple HDMI inputs, USB connectivity, Intelligent Sensor technology for automatic picture optimization, Clear Voice II for enhanced dialogue clarity, and energy-saving features. This service manual provides comprehensive technical information for service technicians including disassembly procedures, circuit diagrams, troubleshooting guides, and replacement parts information.

1. Product Overview 2. Technical Specifications 3. Disassembly Procedures 4. Circuit Diagrams 5. PCB Layouts 6. Troubleshooting Flowcharts 7. Replacement Parts List 8. Adjustment Procedures 9. Safety Precautions 10. Block Diagrams 11. Service Mode Instructions

Product Overview

The LG 42LH30-UA LCD TV features advanced video processing with 120Hz refresh rate, 3 HDMI inputs, PC input, component video inputs, and USB 2.0 port for multimedia playback.

Component	Description
Main Board	EZP602S01A - Main processing unit with HDMI switching
Power Supply	EAY40559401 - Switching power supply board
T-Con Board	6870C-0511A - Timing controller for LCD panel
LCD Panel	LC420WUE-SFB1 - 42-inch Full HD LCD panel
Inverter Board	EAX41228901 - CCFL backlight inverter
Remote Control	AKB72915207 - Standard infrared remote

Technical Specifications

Display: 42-inch LCD, 1920x1080 resolution
Brightness: 500 cd/m²
Contrast Ratio: 80,000:1 (Dynamic)
Response Time: 5ms
Viewing Angle: 178°/178°
Inputs: 3x HDMI, 2x Component, 1x PC (D-Sub), 2x Composite, 1x USB
Tuner: ATSC/NTSC/QAM
Power Consumption: 150W (typical), <1W (standby)
Power Supply: 100-240V AC, 50/60Hz
Dimensions: 40.2" x 26.5" x 3.5" (with stand)
Weight: 32.4 lbs (with stand)

Disassembly Procedures

Follow these steps carefully to disassemble the unit for service.

Remove Stand: Lay TV face down on soft surface, remove 4 screws securing stand.
Remove Rear Cover: Remove all visible screws from rear cabinet, carefully separate rear cover from front bezel.
Access Main Boards: Remove metal shield covering main boards by removing 6 screws.
LCD Panel Removal: Remove bezel screws, carefully separate LCD panel from chassis.
Backlight Access: Remove diffuser sheets and CCFL lamps following ESD precautions.

WARNING! Always discharge power supply capacitors before working on power board. Handle LCD panel with extreme care to avoid damage.

Circuit Diagrams

Complete schematic diagrams for all major circuits including power supply, main board, and audio sections.

Diagram	Page	Description
Power Supply	5-1 to 5-3	EAY40559401 complete schematic
Main Board	5-4 to 5-8	EZP602S01A processor and memory circuits
Audio Section	5-9 to 5-10	Amplifier and speaker circuits
T-Con Board	5-11 to 5-12	Timing controller and LVDS interface
Inverter Board	5-13 to 5-14	Backlight inverter and protection circuits

PCB Layouts

Component placement and routing diagrams for all printed circuit boards.

Main Board Top: Component side layout with reference designators
Main Board Bottom: Solder side layout and test points
Power Supply Top/Bottom: High voltage section clearly marked
T-Con Board: LVDS connector and timing components
Inverter Board: Transformer locations and high voltage areas

Note: All layouts include component values and test point voltages.

Troubleshooting Flowcharts

Step-by-step diagnostic procedures for common failure modes.

Symptom	Diagnostic Steps	Test Points
No Power	Check AC input, standby voltage, main B+, power-on signal	STBY5V, PWR_ON, B+_MAIN
No Backlight	Verify inverter enable, check lamp voltages, test CCFLs	BL_ON, INV_24V, LAMP_TEST
No Video	Check LVDS signal, T-Con voltages, panel VCOM	LVDS_CLK, VCC_Tcon, VCOM
No Sound	Test audio IC, speakers, input signals	AUDIO_IN, SPK_OUT, MUTE
HDMI Issues	Verify EDID, check HDMI IC, test DDC lines	HDMI_5V, DDC_CLK, DDC_DATA

Replacement Parts List

Complete list of service parts with LG part numbers.

Part Number	Description	Qty
EAY40559401	Power Supply Board Assembly	1
EZP602S01A	Main Board Assembly	1
6870C-0511A	T-Con Board Assembly	1
EAX41228901	Inverter Board Assembly	1
LC420WUE-SFB1	LCD Panel Complete	1
AKB72915207	Remote Control Unit	1
10-3512-01	Main Board IC (Video Processor)	1

Adjustment Procedures

Factory adjustment and calibration procedures using service remote.

White Balance: Enter service mode, adjust R/G/B gains and offsets
Geometry: Adjust horizontal/vertical position and size
Color Temperature: Set to 6500K standard using color analyzer
Backlight Level: Adjust to 200 cd/m² for standard operation
Audio Levels: Calbrate volume curve and balance

CAUTION! Record original values before making adjustments. Use proper test equipment.

Safety Precautions

Critical safety information for service personnel.

Always disconnect AC power before servicing
Discharge high voltage capacitors in power supply
Use isolation transformer when testing live circuits
Handle LCD panel with ESD protection
Replace safety critical components with exact equivalents
Reassemble all covers and shields completely

WARNING! High voltage present in power supply and inverter circuits. Risk of electric shock.

Block Diagrams

System-level block diagrams showing signal flow and power distribution.

Diagram	Description
System Block Diagram	Overall signal processing flow from inputs to display
Power Distribution	Voltage rails and power sequencing
Video Processing	Scaler, deinterlacer, and enhancement circuits
Audio Processing	Audio decoding and amplification path
Control System	Microprocessor and interface circuits

Service Mode Instructions

Accessing and navigating the service menu for diagnostics and adjustments.

Enter Service Mode: Press MENU on TV, then press 1-1-2-5 on remote within 3 seconds
Navigation: Use arrow keys to navigate menu options
Adjustment Menu: White balance, geometry, and option settings
Diagnostic Menu:Error logs and self-test functions

Exit Service Mode: Press EXIT or power off TV