lg 50pg20-ua service manual

The LG 50PG20-UA is a 50-inch plasma television featuring HD resolution, built-in ATSC/NTSC tuner, multiple input options including HDMI, component, composite, and PC inputs. This service manual provides detailed technical information for qualified service technicians including safety precautions, disassembly procedures, troubleshooting guides, circuit diagrams, and replacement part information.

1. Safety Precautions 2. Product Specifications 3. Disassembly Procedures 4. Circuit Diagrams 5. Troubleshooting Guide 6. Replacement Parts List 7. Test Points & Measurements 8. Firmware Update Procedures 9. Service Mode Access 10. Warranty Information

Safety Precautions

Important safety information for service technicians working on the LG 50PG20-UA plasma television.

WarningDescription
High VoltagePlasma panel operates at high voltages up to 400V DC
Capacitor DischargeAllow 5 minutes for power supply capacitors to discharge
ESD ProtectionUse anti-static wrist strap when handling circuit boards
Panel HandlingPlasma panel is fragile; handle with care to avoid breakage
Power SupplyDisconnect AC power before servicing
Heat SinksSome components may be hot during operation
X-Ray RadiationNo X-ray radiation emitted during normal operation
Replacement PartsUse only LG-approved replacement parts

Product Specifications

Disassembly Procedures

Step-by-step instructions for disassembling the LG 50PG20-UA plasma television.

  1. Remove stand: Lay TV face down on soft surface, remove screws securing stand.
  2. Remove rear cover: Remove all screws from rear cover, carefully lift off cover.
  3. Disconnect cables: Note cable positions before disconnecting from main board.
  4. Remove main board: Remove screws securing main board, lift board out carefully.
  5. Remove power supply: Disconnect all cables, remove screws, lift power supply board.
  6. Access plasma panel: Remove metal shielding to access panel connections.

WARNING! Always discharge capacitors before handling power supply components.

Circuit Diagrams

Detailed circuit diagrams for main board, power supply, and control circuits.

Circuit BoardDiagram ReferencePage
Main BoardEAX1234567812-15
Power SupplyEAX1234567916-18
Y-SustainEAX1234568019-21
X-SustainEAX1234568122-24
Control BoardEAX1234568225-27
Logic BoardEAX1234568328-30

Troubleshooting Guide

Common symptoms and solutions for the LG 50PG20-UA plasma television.

SymptomPossible CauseCorrective Action
No powerPower supply failureCheck fuse F101, replace power supply board
No picture/soundMain board failureCheck voltages on main board, replace if necessary
Sound but no pictureY-sustain board failureTest Y-sustain voltages, replace board
Half screen darkX-sustain board failureTest X-sustain board, replace if needed
Color problemsLogic board issueCheck LVDS cable, replace logic board
Image retentionPanel agingRun pixel refresher in service menu
Buzzing soundPower supply componentsCheck capacitors C205, C206

Replacement Parts List

Authorized replacement parts for the LG 50PG20-UA plasma television.

Part NumberDescriptionNotes
EBR45678901ABMain Board AssemblyIncludes tuner and input circuits
EBR45678902ACPower Supply Board120V AC input
EBR45678903ADY-Sustain BoardHigh voltage circuit
EBR45678904AEX-Sustain BoardHigh voltage circuit
EBR45678905AFLogic BoardImage processing
EBR45678906AGControl BoardButton and IR sensor
EBR45678907AHPlasma Panel50-inch HD panel
EBR45678908AIFront BezelBlack finish
EBR45678909AJStand AssemblySwivel base

Test Points & Measurements

Key test points and voltage measurements for troubleshooting.

Test PointNormal VoltageLocation
VS195V DCPower Supply
VA55V DCPower Supply
VSC-190V DCY-Sustain
VE95V DCY-Sustain
VSB5V DCPower Supply
STBY5V5V DCMain Board
A12V12V DCMain Board
D5V5V DCMain Board
D3.3V3.3V DCMain Board

Firmware Update Procedures

Instructions for updating firmware on the LG 50PG20-UA.

  1. Download latest firmware from LG service website.
  2. Extract files to USB drive (FAT32 format).
  3. Turn off TV and insert USB drive in service port.
  4. Enter service mode: Press MENU on TV and remote simultaneously.
  5. Select "Software Update" from service menu.
  6. Follow on-screen instructions to complete update.
  7. Do not power off during update process.

CAUTION! Incorrect firmware can damage the television.

Service Mode Access

How to access and navigate the service menu.

  1. Turn on television.
  2. Press MENU button on both TV and remote simultaneously.
  3. Service menu will appear with following options:
  4. Use arrow keys to navigate, ENTER to select.
  5. Exit service menu by turning off TV.

WARNING! Incorrect service menu settings can cause permanent damage.

Warranty Information

Warranty terms and service center information.

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