Technical description and composition of the LG 42LB677V TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LB677V
Chassis / Version: LD42B
Panel: LC420DUH (PG) (F1)
LED backlight: 42 V14 Slim DRT Rev0.6 1 L1-Type / L2-Type / R1-Type / R2-Type
LED driver (backlight): integrated into PSU
PWM LED driver: iW7025-00
Power Supply (PSU): EAX65424001 (2.7) - LGP42-14LPB
PWM Power: MAP8800 (PFC), ICE3BR4765JZ (Standby)
MainBoard: EAX65384005 (1.2) - EBU62521903
IC MainBoard: CPU: LG1311; EEPROM: AT24C256C-SSHL-T; SOUND: NTP7514
Tuner: TDJM-G101D
Control: WiFi: 2703H-LGSBW41, BEJLGSBW41, EAT62093301
Specifications 42LB677V
LG 42LB677V
General repair guidelines for TV LCD LED
If the TV does not turn on, no control lights are on or blinking, there are no sounds when you turn on, and there is not the slightest sign of operability - the most likely malfunction is in the power module. When repairing the power supply, it is advisable to start the diagnostics by checking the mains fuse and the electrolytic capacitors of the filters of the converter secondary rectifiers. In the event of a fuse breaking, the reason should be sought in the power semiconductor elements of the pulse converter of the main power supply. First of all, it is necessary to check the diodes of the rectifier bridge of the mains voltage and the power key (s) of the converter. The complete inoperability of the power supply unit can be caused by a short circuit in the power elements in the primary circuit, followed by an open fuse, or a short circuit in the loads.
Mos-Fet keys used in switching power supplies (SMPS) rarely fail for no reason to look for when checking other circuit elements. Often the breakdown is caused by malfunctions of electrolytic capacitors or semiconductor elements in the primary circuit, or by a break in the resistors in the stabilization circuits. The ICE3BR4765JZ PWM controller chip may also cause a breakdown of the power switch of the converter.
If the LG 42LB677V does not have an image, but there is sound, a malfunction of the backlight LEDs of the LC420DUH (PG) (F1) panel or their power converter, the LED driver, may occur.
Often in the absence of backlighting, disassembling the panel is required. It is necessary to check the serviceability of the transitions of the LEDs, as well as the reliability of the contact connections in the rulers and connectors.
To check the LED lines for breaks 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.
Repair of the motherboard EAX65384005 (1.2) - EBU62521903 must begin with the diagnosis and verification of all linear stabilizers and power converters of its microcircuits. Sometimes it may be necessary to update the software (software) - flashing FLASH or EEPROM.
Board repair and replacement of CPU chips: LG1311; EEPROM: AT24C256C-SSHL-T; SOUND: NTP7514; are made in the presence of the necessary equipment, and the corresponding element base. Faults associated with the application of BGA processor soldering technologies can be localized by the heating method.
If a TDJM-G101D tuner is suspected of malfunction, first of all, it is necessary to verify the correctness of the software, as well as the presence of the necessary supply voltage levels and data exchange pulses with the processor via the I2C bus on the corresponding tuner pins.
It should be remembered! Attempts to repair the LG 42LB677V TV, in the absence of the necessary qualifications and experience, are categorically not recommended and are fraught with negative consequences, up to the complete non-repairability of the device!
schematic diagram ------------> LG CHASSIS: LD42B MODEL : 42LB67**, 42LB67**-Z*.
User Manual WiFi ------------> LG Wi-Fi Module LGSBW41
The appearance of the MainBoard EAX65384005 is shown in the figure below:EAX65384005
EAX65384005 can be used in TVs:
LG 42LB677V (Panel LC420DUH (PG)(F1)), LG 47LB652V ZA.BRUWLDU (Panel LC470DUH (FG)(P2) 6091L-2683D).
PSU Advanced
According to the conditions of compliance with modern world standards for household switching power supplies, the EAX65424001 module provides for the use of a Power Factor Correction unit. The PFC circuit is a flyback converter based on the MAP8800 PWM controller. The reactance of an electrolytic capacitor of a line filter at a frequency of 50-60 Hz is usually not more than 20-30 ohms and its charge directly from the network through open diodes could reach tens of amperes per pulse if no filtering were applied.
As a result of the PFC conversion, an increased voltage on the capacitor (about 380V) cannot directly open the rectifier diodes, on the anode of which the voltage will always be slightly less (about 300V) and then its charging current will always be limited by the elements of the PWM controller. As a result, the envelope of the high-frequency pulses of the consumed current will repeat the shape and phase of the input sinusoidal voltage. The presence of an increased voltage (+ 380V) on the network capacitor indicates the serviceability of the PFC node.
The appearance of the power supply
Main features of the device LG 42LB677V:
Installed matrix (LED-panel) LC420DUH (PG) (F1).
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the iW7025-00 PWM controller.
The necessary supply voltages for all nodes of the LG 42LB677V TV are generated by the EAX65424001 power module or its analogs using MAP8800 (PFC), ICE3BR4765JZ (Standby) microcircuits.
MainBoard - the main board (motherboard) is an EAX65384005 module, using CPU chips: LG1311; EEPROM: AT24C256C-SSHL-T; SOUND: NTP7514 and others.
The TDJM-G101D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUH-PGF1
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: 400 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 1.06B (10-bit), CIE1931 72%
Response Time: 8/10 (Tr / Td)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V