LG 55LM7600 Service Manual

The LG 55LM7600 is a 55-inch LED TV featuring webOS smart platform, Cinema 3D technology, Magic Remote compatibility, built-in Wi-Fi, multiple HDMI inputs, USB connectivity, and advanced picture processing with LED Plus technology. This service manual covers technical specifications, disassembly procedures, troubleshooting, parts replacement, and maintenance guidelines for qualified service technicians.

1. Product Overview 2. Technical Specifications 3. Disassembly Procedures 4. Main Board Replacement 5. Power Supply Board 6. LED Backlight System 7. Panel Replacement 8. Troubleshooting Flowcharts 9. Error Codes 10. Firmware Update 11. Safety Precautions

Product Overview

Key components: LED panel with webOS smart platform, main board, power supply board, T-CON board, LED backlight assembly, and various input/output interfaces.

ComponentDescription
Main BoardEAX64105004 - Main processing unit with webOS
Power SupplyEAY62837401 - 120V AC input, multiple DC outputs
T-CON BoardEAX64105005 - Timing controller for panel interface
LED DriverEAX64105006 - Controls LED backlight array
Wi-Fi ModuleIntegrated 802.11ac wireless connectivity
Input PanelHDMI x4, USB x3, Component, Composite, Ethernet
Speakers10W x 2 with Clear Voice II technology
Magic RemoteAKB72915207 - Motion-controlled remote
Stand AssemblyAKB72915208 - Swivel stand mechanism
Back CoverPlastic enclosure with ventilation

Technical Specifications

Disassembly Procedures

Required tools: Phillips screwdriver, plastic opening tools, anti-static wrist strap.

  1. Remove Stand: Lay TV face down on soft surface, remove 4 screws securing stand.
  2. Remove Back Cover: Remove all visible screws from back cover, use plastic tools to release clips around perimeter.
  3. Disconnect Cables: Carefully disconnect all ribbon cables and wire harnesses from main board.
  4. Remove Main Board: Remove mounting screws and carefully lift main board from chassis.
  5. Access Power Supply: Remove screws securing power supply board and disconnect all connectors.
  6. Panel Access: Remove bezel screws and carefully separate front bezel from panel assembly.

WARNING! Always disconnect power before disassembly. Handle LCD panel with extreme care to avoid damage.

Main Board Replacement

Part Number: EAX64105004

  1. Disconnect all cables and remove back cover as described in disassembly procedures.
  2. Remove 6 mounting screws securing main board to chassis.
  3. Carefully disconnect all ribbon cables, noting their positions for reassembly.
  4. Remove main board and replace with new unit.
  5. Reconnect all cables, ensuring proper orientation of ribbon connectors.
  6. Reinstall mounting screws and test before reassembling back cover.

Note: After main board replacement, perform firmware update and factory reset.

Power Supply Board

Part Number: EAY62837401

Voltage Outputs:

OutputVoltageCurrentPurpose
PS_ON3.3V500mAStandby power
12V12V4AAudio circuits
24V24V2.5ALED backlight driver
5V5V3AMain board logic
18V18V1AT-CON board

Troubleshooting: Check fuse F101 (4A), main capacitor C101 (450V/120μF), and output voltages under load.

LED Backlight System

The 55LM7600 uses direct LED backlighting with 4 strings of 12 LEDs each.

  1. LED Specifications: 3V per LED, 36V per string, 120mA current
  2. Driver Board: EAX64105006 - Controls current and dimming
  3. Testing Procedure: Use LED tester or external power supply to test each string individually
  4. Replacement: Requires complete panel disassembly - recommended for experienced technicians only

WARNING! LED backlight voltage can be hazardous. Always discharge capacitors before testing.

Panel Replacement

Panel Part Number: LC550EUN

Replacement Procedure:

  1. Remove back cover, main board, and power supply as described.
  2. Remove all screws securing panel to chassis.
  3. Carefully separate panel from chassis, supporting the glass at all times.
  4. Disconnect LVDS cable from T-CON board.
  5. Install new panel and reassemble in reverse order.

CAUTION! LCD panels are extremely fragile. Use proper handling equipment and work on clean, padded surface.

Troubleshooting Flowcharts

SymptomFirst CheckSecondary Check
No PowerCheck AC input, fuse F101Measure standby voltage (3.3V)
No BacklightCheck 24V output, LED driverTest LED strings individually
No PictureCheck T-CON voltages (18V, 12V, 3.3V)Test LVDS signal, replace T-CON
No SoundCheck speaker connectionsTest audio IC, main board audio section
Wi-Fi Not WorkingCheck Wi-Fi module connectionUpdate firmware, replace Wi-Fi module
3D Not WorkingCheck 3D emitter connectionReplace 3D emitter, update firmware

Error Codes

Error CodeDescriptionSolution
E1Main board communication errorCheck main board connections, replace main board
E2T-CON board errorCheck LVDS cable, replace T-CON board
E3LED backlight errorCheck LED strings, replace LED driver
E4Power supply errorCheck power supply voltages, replace power board
E5Temperature sensor errorCheck thermal sensors, replace main board
E6Panel communication errorCheck panel connections, replace panel

Firmware Update

Update Methods:

  1. USB Update: Download firmware from LG service site, extract to USB drive, insert in TV USB port, follow on-screen instructions
  2. Online Update: Through TV menu: Settings > General > About This TV > Check for Updates
  3. Service Tool: Using LG Service Checker for forced updates

Current Firmware Version: 05.00.10

WARNING! Do not interrupt power during firmware update. This may permanently damage the TV.

Safety Precautions

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

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