Technical description and composition of the LG 42LB631V TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LB631V ZL
Chassis / Version: LD42B
Panel: LC420DUH (FG) (A1)
LED driver (backlight): integrated into PSU
PWM LED driver: BD9486F
MOSFET LED driver: MDD3752, 4NF20
Power Supply (PSU): EAX65423701 P / N: 3PCR00439B LGP3942-14PL1 PLDF-L307R
PWM Power: MAP8800 (PFC), FA6A01N (PWM resonant)
MainBoard: EAX65384003 EBR78515108
IC MainBoard: CPU: LG1311; DRAM: H5TQ4G63AFR-PBC; EEPROM: AT24C256C, EMMC: THGBMAG6A2JBAIR
Tuner: EBL61400501 TDJM-G101D
Specifications 42LB631V
LG 42LB631V
General repair guidelines for TV LCD LED
A malfunction of the power supply is often manifested corny - the TV does not turn on, does not make any sounds, does not light up and does not blink with any indicators. In the absence of swollen filter capacitors of the secondary rectifiers, the diagnostics of the power supply should be started by checking the fuse and, if it is broken, it is first necessary to check all the power semiconductor elements of the primary circuit - diodes and transistors for the possibility of an avalanche or thermal breakdown.
The breakdown of the power switch of the pulse converter is often triggered by other elements, for example, in the stabilization or control circuits of this switch, as well as by the damper elements in its drain and TPI winding.
If the LG 42LB631V TV does not have an image, but there is sound, a malfunction in the backlight circuits of the LED panel LC420DUH (FG) (A1) is likely.
The lack of backlight often occurs due to an open circuit in the LED circuit. There is a need for disassembling the panel and checking the LEDs themselves, as well as the same contact connections in the connectors and rations of the terminals.
To open all transitions, several tens of volts or more are necessary, and it is best to use a current source for such purposes. A break in the line of LEDs connected in series cannot be detected with a multimeter or tester without disassembling the panel. In the open panel, it is necessary to check each LED. If your multimeter cannot open the LED transitions in forward bias, then see the presence of the PN transition of the protective zener diode by connecting the probes in the opposite direction. If the zener diode is broken or broken in short-circuit, then the LED is faulty and needs to be replaced.
Repair or diagnostics of the EAX65384003 EBR78515108 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, you should update the software (software).
In some cases, to repair the MB board (SSB), it may be necessary to replace the chips - CPU: LG1311; DRAM: H5TQ4G63AFR-PBC; EEPROM: AT24C256C, EMMC: THGBMAG6A2JBAIR for new or obviously working. In cases where BGA technologies are used, defects are usually localized by the heating method.
If you suspect a malfunction of the EBL61400501 TDJM-G101D tuner, first of all, you need to verify the correctness of the software, as well as the presence of the necessary voltage levels and pulses of data exchange with the processor via the I2C bus at the corresponding terminals of the tuner.
Remember! Attempts at self-repair by users of the LG 42LB631V TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!
schematic diagram ------------> LG Chassis LD43B/LD44B MODEL 42LB62** 42LB62**-Z*.
The appearance of the MainBoard EAX65384003 is shown in the figure below:EAX65384003
EAX65384003 can be used in TVs:
LG 47LB650V ZE (Panel LC470DUH (FG) (P2)), LG 42LB631V ZL (Panel LC420DUH (FG) (A1)), LG 39LB650V (Panel T390HVJ01.2), LG 55LB673V ZB (Panel LC550DUH (PG)(F1)), LG 47LB677V (Panel LC470DUH (FG)(F1)), LG 42LB673V (Panel LC420DUH (PG)(F1)), LG 47LB673V (Panel LC470DUH (PG)(F1)), LG 32LB652V 32LB652V-ZA.BRUWLDU (Panel LC320DUH (FG)(P2)), LG 50LB653V (Panel LC500DUH (FG)(P1)), LG 42LB652V 42LB652V-ZA.BRUWLJU (Panel LC420DUH (FG)(P2)), LG 55LB720V 55LB720V-ZG.BRUWLJU (Panel LC550DUH (PG)(F1)).
PSU Advanced
The EAX65423701 power supply module is made using a Power Factor Correction (PFC) scheme to eliminate multiple AC harmonics introduced into the power supply by the device. The PFC node is a Step-Up Converter based on the MAP8800 PWM controller, which evenly distributes high-frequency impulses of the charging current of the electrolytic capacitor of the rectifier filter of the mains voltage over a period of 50 Hz. The current of its charge in this case will already be determined not by its reactance (usually 10-30 ohms for the network frequency), but by the elements of the converter. As a result, a change in the amplitude of the pulses (envelope) of the consumed current of the converter will repeat the shape and phase of the input sinusoidal voltage. The availability of an increased voltage (about + 380V) in the operating mode on the capacitor of the line filter indicates the serviceability of the PFC node.
The appearance of the power supply
Main features of the device LG 42LB631V:
Installed matrix (LED-panel) LC420DUH (FG) (A1).
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the BD9486F PWM controller. As power elements of the LED driver, keys of the MDD3752, 4NF20 type are used.
The necessary supply voltages for all nodes of the LG 42LB631V TV are generated by the EAX65423701 power module or its analogs using MAP8800 (PFC), FA6A01N (PWM resonant) microcircuits.
MainBoard - the main board (motherboard) is an EAX65384003 module, using CPU chips: LG1311; DRAM: H5TQ4G63AFR-PBC; EEPROM: AT24C256C, EMMC: THGBMAG6A2JBAIR and others.
The tuner EBL61400501 TDJM-G101D provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUH-FGA1
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: IPS, Normally Black, Transmissive
Active Area: 927.94x521.96 mm
Surface: Antiglare (Haze 1%), Hard coating (3H)
Brightness: 300 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6/8 (Tr / Td)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V