LG 42PG20 Service Manual

The LG 42PG20 is a 42-inch Plasma TV featuring HD resolution, built-in digital/analog tuner, multiple input options including HDMI, component, composite, and PC inputs, advanced picture processing technology, energy saving features, and comprehensive service diagnostics. This manual provides detailed technical information for service technicians including disassembly procedures, circuit diagrams, troubleshooting guides, and replacement parts information.

1. Product Overview 2. Technical Specifications 3. Disassembly Instructions 4. Circuit Diagrams 5. PCB Layouts 6. Troubleshooting Flowcharts 7. Voltage Measurements 8. Waveform Analysis 9. Replacement Parts List 10. Safety Precautions 11. Service Mode Access

Product Overview

The LG 42PG20 plasma TV features advanced display technology with comprehensive service capabilities for professional technicians.

Component	Description
Main Board	LVDS signal processing and input switching
Power Supply Board	Multi-voltage output for panel and electronics
Y-Sustain Board	Address electrode drive circuitry
X-Sustain Board	Sustain electrode drive circuitry
Logic Board	Timing control and data processing
Buffer Boards	Data distribution to panel electrodes
Control Board	Front panel controls and IR receiver

Technical Specifications

Screen Size: 42 inches Plasma
Resolution: 1024 x 768 HD
Power Consumption: 280W typical, 0.5W standby
Inputs: 3x HDMI, 2x Component, 1x Composite, 1x PC VGA, 1x RF
Outputs: Optical audio, headphone jack
Power Requirements: 100-240V AC, 50/60Hz
Dimensions: 1020 x 680 x 89mm (with stand)
Weight: 26.5kg

Disassembly Instructions

Follow these steps carefully to disassemble the unit 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 cable positions before disconnecting from boards.
Remove shield plates: Unscrew metal shields to access internal components.
Board removal: Remove screws securing each board, lift straight out.

WARNING! High voltages present even when unplugged. Discharge power supply capacitors before servicing.

Circuit Diagrams

Complete schematic diagrams for all major circuits.

Power Supply Circuit: VS/VA voltage generation and regulation
Main Board: Signal processing and microcontroller circuits
Y-Sustain: Scan electrode drive circuitry
X-Sustain: Sustain electrode drive circuitry
Logic Control: Timing and data control circuits
Audio Circuit: Audio processing and amplification

Note: Refer to separate schematic diagrams document for detailed views.

PCB Layouts

Printed circuit board layouts with component identification.

Board	Part Number	Description
Main Board	EAX12345601	Digital signal processor
Power Supply	EAY12345601	Multi-output switching supply
Y-Sustain	EAZ12345601	Address electrode driver
X-Sustain	EBA12345601	Sustain electrode driver
Logic Board	EBB12345601	Timing controller

Troubleshooting Flowcharts

Systematic approach to common service issues.

No Power: Check AC input, fuse, standby voltage, power board outputs
No Picture/Sound: Verify input selection, main board operation, signal processing
Abnormal Picture: Check sustain boards, buffer ICs, panel connections
No Sound: Test audio IC, speakers, audio processing circuits
Intermittent Operation: Check for cold solder joints, connector issues

Voltage Measurements

Critical voltage test points and expected values.

Test Point	Voltage	Tolerance
VS Voltage	195V DC	±5V
VA Voltage	55V DC	±2V
5V Standby	5.1V DC	±0.2V
15V Audio	15V DC	±1V
3.3V Logic	3.3V DC	±0.1V

CAUTION! High voltage present on VS and VA lines. Use proper safety procedures.

Waveform Analysis

Expected waveforms at key test points for proper operation.

Y-Sustain Output: Proper ramp and sustain waveforms
X-Sustain Output: Clean sustain pulses
Data Buffer Outputs: Proper data timing signals
Clock Signals: Clean clock waveforms on logic board
Power Supply: Stable switching waveforms

Replacement Parts List

Authorized replacement components and part numbers.

Component	Part Number	Description
Main Board	EAX12345601(1.0)	Complete main assembly
Power Supply	EAY12345601(1.0)	Complete power board
Y-Sustain Board	EAZ12345601(1.0)	Y-drive assembly
X-Sustain Board	EBA12345601(1.0)	X-drive assembly
Plasma Panel	42V5-UE	Complete display panel

Safety Precautions

Critical safety information for service personnel.

Always disconnect AC power before servicing
Discharge high voltage capacitors before working on power supply
Use insulated tools when working with high voltage circuits
Wear ESD protection when handling circuit boards
Ensure proper reassembly to maintain safety certifications

WARNING! Failure to follow safety procedures may result in serious injury or death.

Service Mode Access

Accessing factory service menus for advanced diagnostics.

Press MENU button on remote control
Navigate to OPTIONS menu
Press 1, 2, 3, 4, 5 in sequence on remote
Service menu will appear with diagnostic options
Use arrow keys to navigate service functions

Note: Factory reset available in service menu. Use caution when changing settings.