Technical description and composition of the LG 50UM7300 TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 50UM7300
Chassis / Version: EAX68253604
Panel: NC500DQG-VXHX3
LED backlight: Direct LED
LED driver (backlight): integrated into PSU
MOSFET LED driver: TO-252
Power Supply (PSU): EAX68249201 (1.8) LGP50T-19U1 EAY65228801
PWM Power: PFC, PWM
MOSFET Power: N-FET TO-252
MainBoard: EAX68253604 (1.0)
IC MainBoard: CPU, DC / DC, eMMC, DRAM, AUDIO
Tuner: EBL61920303 TDJA-Q701D
Specifications 50UM7300
LG 50UM7300
General repair guidelines for TV LCD LED
Possible malfunctions
- LG 50UM7300 does not turn on and does not show any signs of performance at all. Does not blink indicators and does not respond to control buttons.
With such manifestations, a malfunction is most likely to be detected in the EAX68249201 power supply module. It is necessary to measure its secondary output voltages, and if they are absent, check the power switches and rectifier diodes in the converters for a short circuit.
In case of diode breakdowns in the secondary circuits, the converter can operate in emergency short-circuit mode without output voltages, and during short circuit in the power elements of the primary circuit, the mains fuse and / or current sensor at the source of the key usually breaks.
Breakdown of power switches (MosFet) in pulsed sources is sometimes caused by malfunctions of other circuit elements, for example, in circuits supplying a PWM controller, frequency-setting or damper ones, as well as in negative feedback (OOS) stabilization circuits. PWM controllers (PWM), if they do not have visible damage to the chassis and open short circuit between the terminals, are usually checked by replacement.
- There is no image, but there is sound and reaction to commands from the remote control. Or the image appears immediately after turning on and disappears.
Often in such cases, there is no LED backlight. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
It is impossible to check the line of series-connected LEDs without a special current source, and for this purpose it is not safe to use any voltage sources above 12V for them. Then it remains only to open the panel and check each LED separately. Usually, Chinese 9V-powered multimeters light up a single 3-volt LED, if you connect the probes in the forward direction, the red probe to the anode, and the black to the cathode. In dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of health. In the event of a LED malfunction, its zener diode will either be cut off or broken into short-circuit.
- The indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the EAX68253604 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU, DC / DC, eMMC, DRAM, AUDIO and failed chips replace with new ones. Some malfunctions can be associated with the use of BGA soldering technologies in modern Main Board. Typically, such defects are detected by local heating of the chip.
The malfunction of the EBL61920303 TDJA-Q701D tuner is established after checking the software and all the supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
Owners and users of the LG 50UM7300 TV should remember that self-repair without special knowledge, skills and qualifications can be fraught with negative consequences that can lead to complete non-repairability of the device!
The appearance of the MainBoard EAX68253604 is shown in the figure below:EAX68253604
Main features of the device LG 50UM7300:
Installed matrix (LED-panel) NC500DQG-VXHX3.
To power the backlight LEDs, a converter is used, combined with a power supply. As power elements of the LED driver, keys of the TO-252 type are used.
The necessary supply voltages for all nodes of the LG 50UM7300 TV are generated by the EAX68249201 power supply module or its analogs using PFC, PWM microcircuits and power switches of the N-FET TO-252 type.
MainBoard - the main board (motherboard) is an EAX68253604 module, using CPU, DC / DC, eMMC, DRAM, AUDIO, and others.
The tuner EBL61920303 TDJA-Q701D provides reception of television programs and tuning to channels.
