LG LED, OLED, LCD TV Circuit Diagram, Service Manual

In order to download repair instructions for LG TVs, select the model that matches your device.

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Standard Repair Process, schematic circuit diagram, block diagram, 

• LG Color TV, Plasma TV, TVCR Service Manual>>

LG OLED TV, LED TV, LED LCD TV. Full HD 1080P, 2K, 4K,

A broken backlight may appear on the TV screen as follows:

• no picture but sound
• screen flickering at certain intervals
• after a short time the image disappears, after a certain time the picture appears
• the top or bottom, and sometimes the middle part of the screen is darkened, which causes severe discomfort and strain on vision when viewing
• bright light spots on the screen that interfere with viewing
• distortion of colors into the blue spectrum

Comprehensive information about a non-working unit can only be obtained through a complete diagnosis of any LG television device. Correct diagnosis is 85% of repair success.

Troubleshooting is performed in the following sequence:

• Visual inspection of the power supply board
• Checking the power supply and corresponding output voltages
• Measuring the voltage supplied to the driver backlight

Making sure that the voltage increased at the moment of switching on to 150 Volts, and then decreased after 3 - 5 seconds to 100 Volts (depending on the TV model); We realized that the power supply and the driver are working properly. This means that the SMD LEDs installed on the strips are faulty, it’s time to start repairing the LG.

Using a Quick 857DW+ hot-air soldering station, we solder the LED at a temperature of 280 degrees and an air flow of 5. Then we solder a new LED 35*35, 6.8V at 350 milliamps. We repeat the procedure 31 more times. To prevent damage to LEDs from thermal overheating, special equipment and consumables are used. For example, German Martin flux is used for soldering LEDs. You can acquire the skill of installing SMD components in a course on repairing modern TVs.

Backlight circuit

The main elements of the TV backlight unit are:

• LEDs
• transistor
• resistor
• connection connector

To generate the supply voltage for LEDs, the following is used:

• driver
• inductor
• Schottky diode
• smoothing capacitor

TV assembly

We glue the strips to the TV body. We connect the strips through a connector to each other. We check the glow of all LEDs and the accuracy of installation of LED lenses using a mounting reflector.

We install a white reflective screen on the TV body. The purpose of the screen is to improve reflective properties. The reflector is attached to the LG case using 2-sided 3M tape.

We install scattering filters. We make sure that the resulting white field glows uniformly. If there are no highlights, install the matrix in place in the reverse order. We connect to the matrix all the cables necessary for its operation.

We completely assemble the TV, installing the front frame and sound speakers. We connect the TV control system to work with the remote control.