REPAIRING / SERVICING TV LG 65UJ634V

Technical description and composition of the LG 65UJ634V TV, panel type and modules used. The composition of the modules.
LG LED
Model: 65UJ634V
Panel: NC650DGE AAFX7
LED driver (backlight): integrated into PSU
PWM LED driver: 18 pin
MOSFET LED driver: TO-252
Power Supply (PSU): EAX67189001 (1.4) LGP6560DJ-17U1
PWM Power: PFC (SO-8) & PWM (18 pin)
MOSFET Power: TO-220F (PFC), TO-252
MainBoard: EAX67166104 (1.0)
IC MainBoard: CPU, NAND, DRAM, AUDIO, DC / DC
Tuner: TDJN-G501D
Specifications 65UJ634V
LG 65UJ634V
General recommendations for TV LCD LED repair
Possible manifestations of defects
- LG 65UJ634V 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.
Usually with similar manifestations, the defect is caused by faulty elements in the main power supply module EAX67189001. Then we recommend measuring its output voltages and, if they are absent, you should check the serviceability of the power switches (TO-220F (PFC), TO-252) and the rectifier diodes of the converters for a possible short circuit.
In the event of diode breakdowns in the secondary circuits, the converter can operate in an emergency mode of short circuit without output voltages, and in the event of a short circuit in the power elements of the primary circuit, the mains fuse and / or the current sensor in the source of the key usually breaks off.
Mos-Fet power switches used in switching power supplies sometimes fail due to a malfunction of any other elements that can disable it in the key mode, or create an excess of the maximum permissible key parameters. These can be elements supplying a PWM regulator, frequency setting or damper circuits, or elements of negative feedback in the stabilization circuit. PWM controllers PFC (SO-8) & PWM (18 pin), in the absence of visible damage or outright short circuits between the terminals, are checked by replacing them with new ones, or known to be working properly.
- There is no picture, but there is sound and reaction to the remote control. Or, for a second, the image may appear immediately after switching on.
The backlight of the matrix (LED panel) is usually faulty in these cases. 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.
When diagnosing, it must be borne in mind that it is impossible to check for an open in the circuit of the LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally a current source. By opening the panel, you can check each LED separately. Typically, Chinese multimeters will lightly light one 3-volt LED if you connect the probes to it in the forward direction. 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 blinks or is on constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the EAX67166104 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). Sometimes it is necessary to check or replace (if necessary) the elements of the MainBoard - CPU, NAND, DRAM, AUDIO, DC / DC. In cases where a BGA processor is used, its malfunction is usually detected by the local warm-up method.


If the LG 65UJ634V has no picture, but there is sound, often the NC650DGE AAFX7 display backlight simply does not work. Moreover, in LED TVs, the LEDs inside the panel usually fail, less often the LED driver.
In such cases, you can see a barely noticeable image with a successful hit of external light on the screen.

Replacing the LEDs requires disassembling the NC650DGE LCD panel, a process that requires experience and qualifications from the technician. We do not recommend doing such work on your own to the owners of TVs and craftsmen who do not have experience in repairing LCD panels

If there is no image, and the backlight is on, the screen becomes slightly lighter when turned on, and in an open TV you can see the light through the holes in the panel case.
In this case, the panel may also be faulty - damage to the strips, loops, for example, as a result of moisture ingress after unsuccessful washing of the screen, the T-CON (Timing Controller) board may be faulty. But the main board MainBoard EAX67166104 often turns out to be faulty, a software failure is also possible.
Then, first of all, it is necessary to check the panel supply voltage, the 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 the passage of LVDS signals from the MainBoard EAX67166104 with an oscilloscope, as well as synchronization signals to the loops with drivers.
Flooded or unsuccessfully washed screens of LED TVs can be restored, in about half of the cases, usually if significant damage has not formed in the loops and panel strips.

If the TV operates normally from external devices but does not tune to TV channels, the TDJN-G501D tuner may be faulty. 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.

Users and owners of TVs should remember that attempts to self-repair the LG 65UJ634V TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!

DOWNLOAD SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    CHASSIS : UD74Q  for models  60UJ634V, 60UJ634V-ZD, 65UJ634V, 65UJ634V-ZD

Additional MainBoard Repair
The appearance of the MainBoard EAX67166104 is shown in the figure below:
EAX67166104
External view of the power supply
Main features of the LG 65UJ634V device:
Installed matrix (LED-panel) NC650DGE AAFX7.
A converter combined with a power supply is used to power the backlight LEDs and is controlled by an 18 pin 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 65UJ634V TV is carried out by the EAX67189001 power module, or its analogs using PFC (SO-8) & PWM (18 pin) microcircuits and TO-220F (PFC), TO-252 power switches.
MainBoard - the main board (motherboard) is an EAX67166104 module using CPU, NAND, DRAM, AUDIO, DC / DC chips and others.
The TDJN-G501D EP provides TV reception and channel tuning.



 TV LG 65UJ634V with LCD NC650DGE-AAFX7, diagonal size 64.5 "(164 cm) 16: 9 format. The LCD-panel implements the principle of direct backlight display with rear LEDs - Direct LED.
The NC650DGE-AAFX7 sensor and MainBoard EAX67166104 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 65UJ634V 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), DivX, 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.
The TV uses an EAX67189001 power supply.
Dimensions: with stand 1471x910x336 mm, without stand 1471x855x84 mm.
TV weight: with stand: 23.9 kg, without stand: 22.3 kg.
Attention! The NC650DGE-AAFX7 panel of the LG 65UJ634V 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.