Technical description and composition of the LG 55UM7300 TV, panel type and modules used. The composition of the modules.LG LED
Model: 55UM7300 55UM7300PLB
Chassis / Version: LJ9 CHASSIS
Panel: AC550DQG-SLKM3_RA / LC550DQJ (SM) (A1)
LED backlight: SSC_Y19_Trident_55UM73
LED driver (backlight): integrated into PSU
PWM LED driver: SO-8
MOSFET LED driver: TO-252
Power Supply (PSU): EAX68284301 (1.6) LGP55T-19U1
PWM Power: PFC, PWM
MOSFET Power: TO-252
MainBoard: EAX68253605 (1.1) EBT66066234
IC MainBoard: CPU, DC / DC, eMMC, DRAM, AUDIO
Tuner: TDJA-Q701D
Control: Wi-Fi: TWCM-K505D EAT64454802
Specifications 55UM7300
LG 55UM7300
General recommendations for TV LCD LED repair
Possible malfunctions
- LG 55UM7300 TV does not turn on. There are no signs of operability. The indicators on the front panel do not light or blink, the TV does not respond to the control buttons.
In some of these cases, a malfunction is detected in the EAX68284301 power supply module. In the absence of the necessary supply voltages in the secondary circuits of the converters, it is necessary to check the power switches (TO-252) and rectifier diodes for possible partial or complete breakdown.
In case of breakdowns in the secondary circuits, the converter, as a rule, can operate in an emergency in the short-circuit mode, and in case of a short circuit in the power elements of the primary circuit, the mains fuse is usually cut off.
Breakdown of power switches (MosFet) in switching sources is sometimes caused by malfunctions of other circuit elements, for example, in the circuits supplying the PWM controller, frequency setting or damper, as well as in the circuits of Negative Feedback (OOS) stabilization. PWM controllers (PWM) PFC, PWM, if they do not have visible damage to the case and an outright short circuit between the pins, are usually checked by replacement.
- No picture, sound, all other TV functions are working. When turned on, the image may sometimes appear for a second.
A malfunction is usually in these cases most likely in the backlight units of the display matrix. Usually the cause of the malfunction is in the breakage of the LEDs, or in the connectors of the LED strips, but sometimes the LED driver is also faulty.
Without a special current source, it is impossible to check the line of series-connected LEDs, and it is unsafe for them to use any voltage sources over 12V for this purpose. Then all that remains is to open the panel and check each LED separately. Typically, Chinese multimeters with a 9V power supply lightly light up one 3-volt LED if you connect the probes to it in the forward direction, the red probe to the anode, and the black one to the cathode. For dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of LED health. In the event of a malfunction of the LED, its zener diode will either be cut off, or broken through in the K / Z.
- The indicator on the front panel blinks, the TV does not turn on in operating mode, does not respond to the remote control.
Repair or diagnostics of the EAX68253605 motherboard should begin with checking the stabilizers and power converters required to power the microcircuits and matrix. If necessary, you should update or replace the software (software). When repairing an MB board, it is necessary to check its components CPU, DC / DC, eMMC, DRAM, AUDIO. Defective elements must be replaced. If chips with BGA soldering technology are used, the problem in its implementation is detected by local heating of the chip.
If the TV operates normally from external devices, but does not tune to TV channels, the TDJA-Q701D tuner may malfunction. In such cases, first of all, you should make sure that there are supply voltages at its corresponding terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus. Sometimes the reason for the inoperability of the tuner may be a software failure.
Attention! Users and owners of 55UM7300 TVs who do not have the appropriate qualifications, knowledge and experience are strongly discouraged from trying to repair themselves in order to avoid negative consequences that can lead to the complete non-repairability of the device.
Additional MainBoard RepairThe appearance of the MainBoard EAX68253604 is shown in the figure below:
EAX68253604
External view of the power supply
Main features of the LG 55UM7300 device:
Installed matrix (LED panel) AC550DQG-SLKM3_RA / LC550DQJ (SM) (A1).
To power the backlight LEDs, a converter combined with a power supply is used, controlled by an SO-8 PWM controller. TO-252 switches are used as power elements of the LED driver.
The formation of the necessary supply voltages for all nodes of the LG 55UM7300 TV is carried out by the EAX68284301 power module, or its analogs using PFC, PWM microcircuits and power switches of the TO-252 type.
MainBoard - the main board (motherboard) is an EAX68253605 module, using CPU, DC / DC, eMMC, DRAM, AUDIO and others.
Tuner TDJA-Q701D provides reception of television programs and tuning to channels.
There are files to download for 55UM7300PLB from the manufacturer site: < HERE >
Files with updates and instructions:
File Description File Name Type Date Size
SW File (Version 04.80.15). Firmware (USB) Software_File (Version_04.80.15) .zip ZIP 08.07.2020 912984K
Compatible with 43UM71007LB, 43UM7100PLB, 43UM7300PLB, 43UM7390PLC, 43UM7400PLB, 43UM74507LA, 43UM7450PLA, 43UM7490PLC, 43UM7500PLA, 43UM76007LB, 43UM7600PLB, 43UM7650PLA, 49SM8000PLA, 49SM82007LA, 49SM8200PLA, 49UM71007LB, 49UM7100PLB, 49UM7300PLB, 49UM7390PLC, 49UM7400PLB, 49UM7450PLA, 49UM7490PLC, 50UM7300PLB, 50UM74507LA, 50UM7450PLA, 50UM7500PLA, 50UM76007LB, 50UM7600PLB, 50UM7650PLA, 55SM8000PLA, 55SM82007LA, 55SM8200PLA, 55UM71007LB, 55UM7100PLB, 55UM7300PLB, 55UM7400PLB, 55UM74507LA, 55UM7450PLA, 55UM7510PLA, 55UM76107LB, 55UM7610PLB, 55UM7660PLA, 60UM71007LB, 60UM7100PLB, 65SM8000PLA, 65SM82007LA, 65SM8200PLA, 65UM7100PLA, 65UM7300PLB, 65UM7400PLB, 65UM74507LA, 65UM7450PLA, 65UM7510PLA, 65UM76107LB, 65UM7610PLB, 65UM7660PLA, 70UM7100PLA, 70UM7450PLA, 75UM7110PLB, 75UM7600PLB.
SW File (Version 04.80.15). Update instructions TV_Software_Update_Guide_v3.pdf PDF 07/08/2020 2014K
User Manuals and Instructions:
Document Language Date Size
Quick Start Guide English - English, Estonian, Latvian, Lettish, Lithuanian, Russian 10/07/2020 No data
Quick Start Guide English - English, Estonian, Latvian, Lettish, Lithuanian, Russian 10/07/2020 57 244K
User manuals English - English 06.19.2020 13920K
The files can be downloaded on the manufacturer's website for the 55UM7300PLB model.
LG 55UM7300 TV with LCD AC550DQG-SLKM3_RA, 55 "(140 cm) diagonal, 16: 9 format. The LCD panel implements the principle of direct display backlighting with rear-mounted LEDs - Direct LED.
The AC550DQG-SLKM3_RA sensor and MainBoard software are capable of realizing the highest UHD image quality at 3840x2160 resolution in 4K UHD, HDR. Image processing is performed using modern High Dynamic Range (HDR) technology with an extended range of brightness gradations.
TV model 55UM7300 has built-in SMART software and webOS operating system installed. The connection to the network can be carried out via Wi-Fi wireless connection. Supported media file formats: MP3, WMA, MPEG4, HEVC (H.265), MKV, JPEG.
Speaker sound system power 20 W (2x10 W) is provided by two speakers. The NICAM stereo audio processing system and the Sound Surround function are used.
Communication with other devices via an external interface is supported by standard input and output connectors: antenna input (RF), AV, component, HDMI x3, USB x2, Ethernet (RJ-45), Bluetooth, Wi-Fi 802.11ac, WiDi, Miracast.
The digital tuner can receive TV channels in the DVB-T MPEG4, DVB-C, DVB-T2, DVB-S2 standards.
Dimensions: with stand 1245x785x231 mm, without stand 1245x736x86 mm.
TV weight: with stand: 14.2 kg, without stand: 14 kg.
Attention! The AC550DQG-SLKM3_RA panel of the LG 55UM7300 LED TV is an expensive and unreliable element.
Do not allow any impact on the glass and pressure on the screen surface to avoid damage to the LED panel!
It is also unsafe for liquid to spill onto the screen. Sometimes one drop is enough if it drips down the glass onto the cables to make the TV unrepairable.