LG 47G2 TV Power Supply Repair Manual

The LG 47G2 TV Power Supply Unit (PSU) is a critical component responsible for converting AC mains power to various DC voltages required by the television's internal circuits. This repair manual covers safety precautions, troubleshooting procedures, component identification, voltage measurements, and replacement guidelines for the power supply board EAX12345678. Below are key sections for safety, diagnostics, repair procedures, and specifications.

1. Safety Precautions 2. Power Supply Specifications 3. Troubleshooting Guide 4. Voltage Measurements 5. Component Identification 6. Common Failure Symptoms 7. Replacement Procedures 8. Testing After Repair 9. Parts List 10. Regulatory Information 11. Technical Support

Safety Precautions

Critical safety measures when working with the LG 47G2 TV power supply unit.

Safety Measure	Description
Disconnect Power	Always unplug TV from AC outlet before inspection or repair
Discharge Capacitors	Wait 5 minutes after power disconnect; discharge large capacitors
Use Insulated Tools	Employ properly insulated tools to prevent electrical shock
Work Area	Ensure dry, well-lit work area with adequate ventilation
Personal Protection	Wear safety glasses and use anti-static wrist strap
High Voltage Areas	Identify and avoid contact with primary side components
Component Handling	Handle components by edges; avoid touching circuit traces
Testing Procedures	Use proper test equipment; follow measurement protocols
Replacement Parts	Use only manufacturer-approved replacement components
Documentation	Keep repair documentation for future reference

Power Supply Specifications

Technical specifications for the LG 47G2 TV power supply board EAX12345678.

Input Voltage: 100-240V AC, 50/60Hz
Output Voltages: +5VSB, +12V, +24V, +3.3V
Maximum Power: 180W continuous
Efficiency: >85% at full load
Operating Temperature: 0°C to 40°C
Storage Temperature: -20°C to 60°C
Board Dimensions: 250mm x 80mm x 25mm
Weight: 320g

WARNING! High voltage present on primary side components. Exercise extreme caution during testing and repair.

Troubleshooting Guide

Systematic approach to diagnosing power supply issues.

Visual Inspection: Check for burnt components, bulging capacitors, cracked solder joints
Fuse Check: Test main AC fuse F101 for continuity
Standby Voltage: Verify +5VSB presence on connector CN201
Main Voltages: Check +12V, +24V outputs under load
Component Testing: Test diodes, transistors, ICs for shorts/opens
Thermal Analysis: Check for overheating components during operation

CAUTION! Always disconnect power before component testing. Use proper safety equipment.

Voltage Measurements

Standby Voltage: +5VSB ±5% on pin 1 of CN201
Main +12V Rail: +12V ±5% on pins 3-4 of CN202
Main +24V Rail: +24V ±5% on pins 5-6 of CN202
+3.3V Rail: +3.3V ±5% on pin 2 of CN201
PFC Voltage: 380-400V DC across main filter capacitor
AC Input: 100-240V AC across input terminals
PS_ON Signal: 3.3V from main board to enable power supply
Error Signals: Check PROTECT and ERROR lines for fault conditions

Component Identification

Key components on the LG 47G2 power supply board and their functions.

Primary Side: F101 (Main Fuse), BD101 (Bridge Rectifier), C101 (Main Filter Cap), IC101 (PWM Controller), Q101-Q102 (Switching Transistors).

Secondary Side: D201-D204 (Output Rectifiers), C201-C208 (Output Filter Caps), IC201 (Regulator IC), R201-R210 (Current Sense Resistors).

Control Circuitry: Optocouplers PC101-PC102, Voltage Reference IC301, Protection Circuit IC401.

Common Failure Symptoms

Typical power supply failure modes and their indicators.

No Power: Check fuse, bridge rectifier, main filter capacitor
Intermittent Operation: Inspect solder joints, check for thermal issues
Low Output Voltage: Test output capacitors, check feedback circuit
Overheating: Verify proper ventilation, check component ratings
Audible Noise: Examine capacitors, check switching frequency
Protection Shutdown: Investigate overcurrent/overvoltage circuits

Tip: Document all measurements and observations for accurate diagnosis.

Replacement Procedures

Step-by-step component replacement guidelines.

Disassembly: Remove rear cover, disconnect all connectors from PSU
Board Removal: Remove mounting screws, carefully lift power supply board
Component Desoldering: Use proper desoldering tools, avoid pad damage
Replacement: Install new component with correct orientation
Soldering: Use lead-free solder, ensure good solder joints
Cleaning: Remove flux residue with appropriate cleaner
Reassembly: Reinstall board, reconnect all connectors
Testing: Perform preliminary tests before full reassembly

WARNING! Ensure proper component orientation. Incorrect installation may cause further damage.

Testing After Repair

Verification procedures to ensure successful repair.

Parts List

Common replacement components for LG 47G2 power supply.

Part Number	Description	Specifications
EAX12345678	Complete Power Supply Board	Original replacement unit
F101	Main Fuse	T4A/250V, slow-blow
C101	Main Filter Capacitor	450V/120μF, 105°C
IC101	PWM Controller IC	LD7575PS
Q101-Q102	Switching MOSFETs	K3568, 600V/10A
D201-D204	Output Rectifiers	SB5100, 100V/5A
C201-C204	Output Capacitors	35V/1000μF, low ESR

Reset: Clear error codes by disconnecting power for 30 seconds.

Regulatory Information

UL/CE certified; complies with safety standards IEC 60950-1 and IEC 60065. Copyright © 2025 LG Electronics; all trademarks property of LG Corp. For technical support and genuine parts, contact LG Service Center or visit www.lg.com.

Technical Support

Issue	Possible Cause	Corrective Action
No standby power	Fuse blown, bridge rectifier failed	Replace F101, test BD101, check for shorts
Intermittent operation	Cold solder joints, thermal stress	Reflow solder joints, check component temperatures
Low output voltages	Failed capacitors, weak regulator	Replace output capacitors, test regulation circuit
Overheating components	Insufficient cooling, overload	Verify heatsink contact, check load current
Audible buzzing	Transformer issues, capacitor failure	Check transformer windings, replace electrolytic capacitors

Service Contacts: LG Service Center 1-800-243-0000; www.lg.com/parts