LG LED
Model: 49UM7090PLA
Chassis / Version: EAX68253605
Panel: AC490DGG-SLEM1
LED backlight: HC490DGG-SLTLB LC49490134B LC49490135B
LED driver (backlight): integrated into PSU
PWM LED driver: SO-8
MOSFET LED driver: TO-252
Power Supply (PSU): LGP49DJ-17U1 EAX67189201 (1.6)
PWM Power: PFC, PWM
MOSFET Power: TO-252
MainBoard: EAX68253605 (1.1)
IC MainBoard: CPU, DC / DC, eMMC, DRAM, AUDIO
Tuner: TDJA-Q701D
Specifications 49UM7090
LG 49UM7090PLA
General recommendations for TV LCD LED repair
Possible manifestations of defects
- LG 49UM7090PLA does not turn on, does not respond to buttons and the remote control, indicators on the front panel do not light or flash.
In some of these cases, a malfunction is detected in the LGP49DJ-17U1 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 of semiconductors in the secondary circuits, the converter can usually operate in an emergency in the short-circuit mode, and in the event of a short circuit in the power elements of the primary circuit, the mains fuse often breaks.
Breakdown of Mos-Fet switches used in switching power supplies is often caused by malfunctions of other elements, for example, in the power supply circuit of a PWM regulator, in frequency-setting or damper circuits, as well as in negative feedback stabilization. PWM microcircuits (PWM) PFC, PWM are usually checked by replacing them with new ones, or knowingly working.
- There is no image, there is sound, it reacts to the remote control, the channels are switched. In some cases, the image appears when turned on and disappears immediately.
Often, in such cases, there is no backlighting of the LED panel. The reason may be in the breakage of the backlight LEDs, in the stabilization of their power supply, or in the violation of the contact connections of the HC490DGG-SLTLB LC49490134B LC49490135B strings connectors.
To check the LED strips for breakage without disassembling the panel, for example, a current source will help. It is impossible to open series-connected PN junctions with a simple multimeter; a voltage of the order of several tens of volts is required.
- 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.
Before changing the TDJA-Q701D tuner, if it is not possible to tune to TV channels, you should make sure that there are supply voltages, which must be measured at the corresponding tuner terminals and check the software for correctness. The pulses of data exchange between the tuner and the processor can be monitored with an oscilloscope
Owners of the 49UM7090PLA TV are recommended to contact only qualified specialists with the necessary work experience for repair! Attempts to repair yourself without the appropriate knowledge and skills can lead to irreversible negative consequences!
Additional MainBoard Repair
MainBoard EAX68253605 appearance is shown in the figure below:
EAX68253605
External view of the power supply
Main features of the LG 49UM7090PLA device:
Installed matrix (LED-panel) AC490DGG-SLEM1.
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 49UM7090PLA TV is carried out by the LGP49DJ-17U1 power supply 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 TV programs and tuning to channels.
There are files to download for the model 49UM7090PLA from the manufacturer:
User Manuals and Instructions:
Document Language Date Size
Quick Start Guide English - English, Estonian, Latvian, Lettish, Lithuanian, Russian 11.25.2020 106 879K
Quick Start Guide English - English, Estonian, Latvian, Lettish, Lithuanian, Russian 11.25.2020 No data
Files can be downloaded from the manufacturer's website for model 49UM7090PLA.
LG 49UM7090 TV with LCD AC490DGG-SLEM1, diagonal size 49 "(124 cm) 16: 9 format. The LCD panel implements the principle of direct display backlighting with rear-mounted LEDs - Direct LED.
AC490DGG-SLEM1 sensor and MainBoard EAX68253605 software are capable of realizing images in the highest UHD quality at a resolution of 3840x2160 pixels in 4K UHD, HDR. Image processing is performed using modern High Dynamic Range (HDR) technology with an extended range of brightness gradations.
TV model 49UM7090 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, HEVC (H.265), 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 is capable of receiving television channels in the DVB-T, DVB-T2, DVB-C, DVB-S, DVB-S2 standards.
The TV uses the LGP49DJ-17U1 power supply.
Dimensions: with stand 1110x705x225 mm, without stand 1110x650x81 mm.
Attention! Panel AC490DGG-SLEM1 LED TV LG 49UM7090 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.