Wednesday, 27 January 2021

REPAIRING / SERVICING TV LG 50UK6300PLB

Technical description and composition of LG 50UK6300PLB TV, type of panel and modules used. Module composition.

LG LED
Model: 50UK6300PLB

Chassis/Version: EAX67872805

Panel: HC500DQN-VCUL9

LED backlight: HC500DQN-VCUR/L S

T-CON: EACDJ6E18

LED driver (backlight): integrated into PSU

PWM LED driver: SO-8

MOSFET LED driver: TO-252

Power Supply (PSU): EAX67844401 (1.6) EAY64948601 LGP50T-18U1

PWM Power: PFC, PWM

MOSFET Power: TO-252

MainBoard: EAX67872805 (1.1)

IC MainBoard: CPU, eMMC, EEPROM: 24C256A, DRAM, AUDIO, DC/DC

TGC: TDJA-G601D

Specifications 50UK6300
LG 50UK6300PLB
General recommendations for LCD LED TV repair
Possible Manifestations of Defects

- LG 50UK6300PLB TV does not turn on at all. No reaction to remote control and front panel controls. Indicator lights do not light or blink.

In such cases, the power supply EAX67844401 is usually the defective one. Then we recommend to measure its output voltages and in case they are missing, check the condition of the power switches (TO-252) and rectifier diodes of inverters for possible short circuits.
If the semiconductors in the secondary circuits breakdown, the inverter can usually be short-circuited, and the mains fuse often blows when the primary circuit power elements are shorted.
Mos-Fet power switches used in switching power supplies sometimes fail due to the failure of some other element that can take it out of key mode, or create the maximum allowable parameters of the switch. These can be the elements that feed the PWM controller, the frequency or damping circuits, or the negative feedback elements in the stabilization circuit. PFC, PWM controllers, if there is no visible damage or outright short circuits between pins, are checked by replacing with new or known good ones.

- No picture, but there is sound and reaction to remote control commands. Or the image appears immediately after switching on and disappears.

Usually in such cases the defect is detected in the nodes of LED panel backlighting. The reason for this may be a breakage in the circuit of the LED HC500DQN-VCUR/L S, or a problem in stabilizing their power.
Without a special current source it is impossible to check the line of LEDs in series, and it is not safe for them to use any voltage sources over 12v for this purpose. The only thing you have to do is to open the panel and check each LED separately. Usually Chinese multimeters with 9V power supply will light up one 3 volt LED a bit if you connect the probes to it in forward direction, red probe to anode, black probe to cathode. For twin 6-volt LEDs the PN junction of its faulty regulator can be a good indicator. If the LED is faulty, its regulator will either be open or shorted.

- LED on the front panel is blinking, the TV set does not turn on in the working mode, the remote control is unresponsive.

Repair or diagnosis of the motherboard EAX67872805 should begin with checking the stabilizers and power converters necessary to power the chips and matrix. If necessary, software (software) should be updated or replaced. In cases of complicated MB (SSB) repairs and with the necessary skills and equipment it may sometimes be necessary to replace its CPU, eMMC, DRAM, AUDIO, DC/DC chips and other possible defective components. BGA soldering problems are usually easy to diagnose with the heating method.

If the LG 50UK6300 has no picture but has sound, often the HC500DQN-VCUL9 display backlight simply isn't working. Moreover, in LED TVs, the LEDs inside the panel usually fail, less often the LED-driver.
In such cases you can see a faintly visible image when external light hits the screen.

To replace the LEDs requires disassembly of the LCD panel HC500DQN-VCUL9 - a process which requires the master of experience and expertise. We do not recommend to perform such works by yourself to owners of TV sets and craftsmen who have no experience in LCD panel repair

If there is no image, but backlighting works - the screen becomes slightly lighter when the TV is turned on, and in the open TV you can see the light through the holes in the body of the panel.
In this case the panel may be defective - damage to the strips, cables, for example, as a consequence of moisture after an unsuccessful washing of the screen, the T-CON board (Timing Controller) may be defective. But quite often the MainBoard EAX67872805 is defective, and software failure is also possible.
Then first it is necessary to check the panel power supply voltage, fuses on the T-CON board, as well as the supply and reference voltages of the column and line drivers - VGH, VGL, Vcom.
If these measurements are within normal limits, it is necessary to trace by oscilloscope the LVDS signals from MainBoard EAX67872805, as well as synchronizing signals to driver stubs.

Filled or unsuccessfully washed LED TV screens can be restored in about half of the cases, usually, if there are no significant damages in the cables and panel strips.


The TDJA-G601D tuner malfunction can be diagnosed after checking the software and all supply voltages on its pins. The data exchange between the tuner and the CPU via the I2C bus can be checked with an oscilloscope.

To the owners of the TV set 50UK6300PLB we recommend to apply only to the qualified specialists with the necessary experience for the repair! The attempts of repair without the appropriate knowledge and skills can lead to irreversible negative consequences!

More on MainBoard Repair

The exterior of the MainBoard EAX67872805 is shown in the figure below:




EAX67872805

MainBoard Appearance

The main features of the LG 50UK6300PLB:

A matrix (LED panel) HC500DQN-VCUL9 is installed.
Timing Controller (T-CON) EACDJ6E18 is used to control the matrix.
A converter combined with a power supply is used to power the backlight LEDs, controlled by a SO-8 PWM controller. The power elements of the LED driver are TO-252-type switches.

The formation of the necessary supply voltages for all LG 50UK6300PLB TV nodes performs power module EAX67844401, or its analogues c using chips PFC, PWM and power switches like TO-252.
MainBoard - the main board (motherboard) is an EAX67872805 module, using CPU, eMMC, EEPROM: 24C256A, DRAM, AUDIO, DC/DC and other chips.
The TDJA-G601D tuner provides TV program reception and channel tuning.



Instructions and updates

There are downloadable files for the 50UK6300PLB model from the manufacturer:

Update and instruction files:
File Description File Name Type Date Size
SW File (Version 05.20.15) . TV_Software_Update_Guide_v3.pdf PDF 11.11.2020 2014K update instructions
SW File (Version 05.20.15) . Firmware (USB) Software_File(Version_05.20.15).zip zip 11.11.2020 884809K
Compatible with 43UK6200PLA, 43UK6300LLB, 43UK6300MLB, 43UK6300PLB, 43UK6390PLG, 43UK6400PLF, 43UK6450PLC, 43UK6470PLC, 43UK6500LLA, 43UK6500MLA, 43UK6500PLA, 43UK6510PLB, 43UK6550PLD, 43UK6710PLB, 43UK6750PLD, 43UK6950PLB, 49UK6200PLA, 49UK6300MLB, 49UK6300PLB, 49UK6390PLG, 49UK6400PLF, 49UK6450PLC, 49UK6470PLC, 49UK7500PLC, 49UK7550LLA, 49UK7550MLA, 49UK7550PLA, 50UK6300LLB, 50UK6300MLB, 50UK6300PLB, 50UK6410PLC, 50UK6470PLC, 50UK6500LLA, 50UK6500MLA, 50UK6500PLA, 50UK6510PLB, 50UK6710PLB, 50UK6750PLD, 50UK6950PLB, 55UK6200PLA, 55UK6300LLB, 55UK6300MLB, 55UK6300PLB, 55UK6400PLF, 55UK6470PLC, 55UK6500LLA, 55UK6500MLA, 55UK6500PLA, 55UK6510PLB, 55UK6550PLD, 55UK6710PLB, 55UK6750PLD, 55UK6950PLB, 55UK7500PLC, 55UK7550LLA, 55UK7550MLA, 55UK7550PLA, 60UK6200PLA, 65UK6300LLB, 65UK6300MLB, 65UK6300PLB, 65UK6400PLF, 65UK6450PLC, 65UK6470PLC, 65UK6500MLA, 65UK6500PLA, 65UK6710PLB, 65UK6750PLD, 65UK6950PLB, 65UK7550LLA, 65UK7550MLA, 65UK7550PLA, 70UK6500PLB, 70UK6710PLA, 70UK6950PLA, 75UK6200PLB, 75UK6500PLA, 75UK6750PLB.

Manuals and User Manuals:
Document Language Date Size
Quick Start Guide English - English,Estonian,Latvian,Lettish,Lithuanian,Russian 07.14.2020 55 963K
Quick start guide English - English 05.31.2018 4067K

You can download the files from the manufacturer's website for the model 50UK6300PLB.



LG 50UK6300 TV with HC500DQN-VCUL9 LCD screen, measuring 49.5" (126 cm) diagonally in 16:9 aspect ratio. The required brightness of 200 cd/m² screen luminescence is provided by LED backlighting. Contrast, as the ratio of maximum brightness to minimum brightness, is 1200:1. The LCD panel implements the principle of direct backlighting of the display with the rear arrangement of the LEDs - Direct LED.
HC500DQN-VCUL9 matrix and MainBoard software EAX67872805 are able to realize the image in the highest quality UHD at 3840x2160 pixels in 4K UHD, HDR standard. Image processing is made by modern technology High Dynamic Range (HDR) with an extended range of brightness gradation.
The model of TV 50UK6300 has built-in software (software) SMART and installed the operating system webOS. Connection to the network can be made via Wi-Fi. Supported media formats: MP3, WMA, MPEG4, HEVC (H.265), DivX, MKV, JPEG.
The sound speaker system has a capacity of 20 W (2x10 W) and is equipped with two loudspeakers. NICAM stereo sound processing system and Sound Surround surround function are used.
Communication with other devices via an external interface is supported by standard inputs and outputs: antenna input (RF), AV, component, HDMI x3, USB x2, Ethernet (RJ-45), Bluetooth, Wi-Fi 802.11ac, Miracast. The digital tuner is capable of receiving DVB-T, DVB-T2, DVB-C, DVB-S, DVB-S2 TV channels.

The power consumption in mains mode is 130 watts. Power supply EAX67844401.

Overall dimensions: with stand 1133x723x231 mm, without stand 1133x663x88 mm.

TV weight: with stand: 10.8 kg, without stand: 10.6 kg.

Warning. HC500DQN-VCUL9 panel of LG 50UK6300 LED TV is an expensive and unreliable element of the TV.
Do not allow any impact on the glass and pressure on the screen surface to avoid damaging the LED panel!
Also it is not safe to get liquid on the screen. Sometimes one drop is enough if it drips down the glass onto the cables and the TV becomes unrepairable.