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This document serves as a service manual for an LG LED TV, specifically models 55LH575A, 55LH5750, 55LH575A-UE, and 55LH5750-UB, built on the LA66L chassis. It provides comprehensive information for technicians on troubleshooting, repair, and maintenance of these television sets.
The LG LED TV is designed to provide high-quality visual and audio entertainment. It supports various input sources, including digital and analog TV signals, AV inputs, component video, and HDMI, allowing users to connect a wide range of external devices such as set-top boxes, DVD/Blu-ray players, gaming consoles, and computers. The TV incorporates an M2 (NON MCP) main processor, which manages signal demodulation, video processing, and audio output. It features DDR3 memory for efficient operation and eMMC storage for system files and user data. The television is equipped with a tuner for receiving broadcast signals (ATSC/NTSC-M / 64 & 256 QAM) across VHF, UHF, and CATV channels. Audio is handled by an integrated audio amplifier, delivering sound through internal speakers. Connectivity options include USB for media playback and software updates, Wi-Fi for network access, and an IR/KEY interface for remote control and on-device navigation. The TV also includes SPDIF OUT for digital audio output and an Ethernet port for wired network connections. For certain models, an RS-232 port is available for control and service purposes. The display panel is an LED type, supporting various resolutions up to 1920x1080 (Full HD), ensuring a clear and vibrant picture.
The TV offers a user-friendly interface for navigating channels, adjusting settings, and accessing connected devices. Users can select different input sources (TV, AV, Component, HDMI) to switch between various content providers. The audio settings allow for adjustments to sound output, including selecting "TV Speaker" mode. For software maintenance and updates, the TV supports USB download functionality. This feature allows technicians or users to update the TV's firmware by inserting a USB stick containing the update file into the USB socket. The TV automatically detects the update file and initiates the upgrade process, displaying progress messages such as "Copying files from memory" and "Upgrading...". Upon completion, the TV restarts, and the updated version can be verified. In cases where a software update might clear channel data, the TV provides a mechanism for channel recovery. Additionally, after a download, specific "TOOL OPTION" settings may need to be reconfigured using a service remote controller, allowing for model-specific adjustments. The TV's design includes an exposed metallic parts system that requires safety checks to ensure safe operation and prevent electrical shock hazards.
This service manual emphasizes critical safety precautions for technicians. It highlights that many electrical and mechanical parts have special safety-related characteristics, identified by a specific symbol in the Exploded View, and must be replaced with recommended components to prevent hazards. General servicing guidelines include always unplugging the AC power cord before working on components, using an isolation transformer for non-isolated chassis, and replacing blown fuses with specified types. When replacing high-wattage resistors, a minimum 10mm clearance from the PCB is advised.
For component-level repairs, the manual provides detailed instructions for removing and replacing various parts:
The manual also addresses Circuit Board Foil Repair, providing techniques for repairing damaged copper patterns at IC connections and other areas. This involves carefully removing damaged foil, scratching away solder resist, forming jumper wires, and soldering them in place, with warnings to avoid overheating the PCB foil and ensure insulated jumper wires do not touch other components or sharp edges.
Troubleshooting guides are provided for common issues:
The manual also includes an "Exploded View" diagram to visually identify components and their locations within the chassis, aiding in the repair process. This comprehensive approach ensures that technicians have the necessary information to safely and effectively service the LG LED TV models covered.
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