Technical description and composition of the LG 49LB870V TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 49LB870V
Chassis / Version: LD42A
Panel: LC490EUH (LG) (F1)
LED driver (backlight): integrated into PSU
PWM LED driver: MC93F5516SB, W7011-CU
Power Supply (PSU): EAX65393901 EAY63072501 LGP49-14PL6
PWM Power: EP592BG (PFC) 3BR4765J (Stb), SSC9527C
MainBoard: EAX65609406 (1.1)
IC MainBoard: CPU: LG1311, EEPROM: AT24C256C, DDR: H5TQ4G63AFR, AUDIO: NTP7514
Tuner: TDJM-G251D
Specifications 49LB870V
LG 49LB870V
General repair guidelines for TV LCD LED
Possible malfunctions
- LG 49LB870V 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 EAX65393901 power module. It is necessary to measure its output voltages and, in case of their absence, check the serviceability of power switches and rectifier diodes in the converters for possible breakdown.
In case of breakdowns of semiconductors in the secondary circuits of any converter, as a rule, it can operate in emergency short-circuit mode without output voltages, and during short circuit in the elements of the primary circuit, the main fuse and, less often, the current sensor at the source of the key are most often cut off.
Mos-Fet power switches, used in switching power supplies, sometimes fail due to a malfunction of any other elements that can put it out of operation in key mode or create an excess of the maximum permissible parameters of the switch. These can be elements supplying the PWM controller, frequency-setting or damping circuits, or negative feedback elements in the stabilization circuit. PWM controllers EP592BG (PFC) 3BR4765J (Stb), SSC9527C, in the absence of visible damage or frank short-circuit between the terminals, are checked by replacing with new, or obviously working.
- There is no image, there is sound, it responds to the remote control. Or the image may appear for a second when turned on and immediately disappears.
In most of these cases, a malfunction is detected in the nodes and backlight elements of the LED panel. 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 LED line for breaks without disassembling the panel with a multimeter or tester. For these purposes, it is necessary to open all series-connected PN junctions and a voltage of the order of tens of volts will be required, and ideally, a current source. Having disassembled the panel, it is necessary to check each LED separately. Chinese multimeters, as a rule, light up a single 3-volt LED in the forward direction. In the case of using dual 6-volt LEDs, the PN junction of its protective zener diode can serve as a health indicator. In faulty LEDs, the zener diode will either be cut off or broken into short-circuit.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the EAX65609406 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). Sometimes it is necessary to check or replace (if necessary) the elements of the MainBoard board - CPU: LG1311, EEPROM: AT24C256C, DDR: H5TQ4G63AFR, AUDIO: NTP7514. In cases where the BGA processor is used, its malfunction is usually detected by the local heating method.
The TDJM-G251D tuner malfunction is established after checking the software and all supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
We recommend owners of the 49LB870V TV for repair only to qualified specialists with the necessary work experience! Self-repair attempts without the appropriate knowledge and skills can lead to irreversible negative consequences!
Service manual / schematic diagram ----------------> LG 49LB870V Chassis LD42A
The appearance of the MainBoard EAX65609406 is shown in the figure below:EAX65609406
Main features of the device LG 49LB870V:
Installed matrix (LED-panel) LC490EUH (LG) (F1).
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by the PWM controller MC93F5516SB, W7011-CU.
The necessary supply voltages for all nodes of the LG 49LB870V TV are generated by the EAX65393901 power module or its analogs using EP592BG (PFC) 3BR4765J (Stb), SSC9527C microcircuits.
MainBoard - the main board (motherboard) is an EAX65609406 module, using CPU chips: LG1311, EEPROM: AT24C256C, DDR: H5TQ4G63AFR, AUDIO: NTP7514 and others.
The TDJM-G251D tuner provides TV reception and channel tuning.
