Thursday, 27 February 2020

REPAIR / SERVICING TV LG 42LM580S

Technical description and composition of the LG 42LM580S TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LM580S ZA
Chassis / Version: LD21B
Panel: LC420EUE (SE) (F1)
LED backlight: 6922L-0016A, 6916L0936A 42inch V12 EDGE REV1.1 6920L-0001C
T-CON: 6870C-0401B
LED driver (backlight): integrated into PSU; 67V 0.78A
PWM LED driver: R5F100BCAFP, AAT2430AISX
MOSFET LED driver: PHT4NQ10LT * 4
Power Supply (PSU): EAX64427101 (1.4) - EAY62608901
PWM Power: FAN7930BG (PFC), L6599AD (PWM Resonant), STR-A6059
MOSFET Power: STF13NM60N, STF10NM60N, FDT86106LZ
MainBoard: EAX64317403 (1.0) - EBR75084302
IC MainBoard: CPU: LGE2111A-T8, Nand: NAND01GW3B2CN6E, DDR: H5TQ1G63DFR-H9C, SPI Flash: W25Q80BV
Tuner: TDSQ-G001D - EBL61080101
Control: AKB73615307; IR: LM35-55 Ver.2.2 EBR74561083
Specifications 42LM580S
LG 42LM580S
General repair guidelines for TV LCD LED
Sometimes the LG 42LM580S TV just does not turn on. No control lights on the front panel are lit or blinking, the TV does not respond to the remote control and does not make any sounds or any signs of life when turned on. The most likely cause of the malfunction is the failure of the EAX64427101 (1.4) common power supply module - EAY62608901. If it is working properly, you must check the standby batteries on the Main Board. In the general case, first of all, it is necessary to check the electrolytic capacitors of the secondary rectifier filters and the fuse at the input of the network. If it is cut off, then it is necessary to check the diodes of the rectifier bridge and the key transistor of the converter for a breakdown of the PN junctions, which can either be on a separate radiator or integrated with a PWM controller in a common chip. Possible options.
It should be remembered that in the practice of repair, usually the power switches in switching power supplies (SMPS) do not fail due to their poor quality and, in such cases, it is necessary to look for the cause that led to a malfunction and provoked a breakdown of the key. Most often, the culprits of the accident are dried electrolytic capacitors or dangling resistors in the primary circuit, or the FAN7930BG (PFC) PWM controller chip, L6599AD, STR-A6059, FDT86106LZ, D10100CT may be faulty. It is also necessary to check all the semiconductor elements of the stabilization circuit in the primary and secondary circuit.
If there is no image when you turn on the LG 42LM580S, or it appears and immediately disappears, but there is sound, most likely there is a malfunction in the backlight LED circuit of the LC420EUE (SE) (F1) panel, or in the LED node of the driver-converter of their power supply.
A malfunction in the backlight circuits often occurs due to an open in the power circuit of the LED lines. It is necessary to disassemble the panel and check the LEDs themselves, the soldering of their conclusions, as well as the reliability of the connections in the connectors and the soldering of the conclusions of the connectors.
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 EAX64317403 (1.0) - EBR75084302 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).
If it is not possible to replace the MB (SSB) card, you need to check the health of its elements - CPU: LGE2111A-T8, Nand: NAND01GW3B2CN6E, DDR: H5TQ1G63DFR-H9C, SPI Flash: W25Q80BV. Defective components should be replaced.
Malfunction of the tuner TDSQ-G001D - EBL61080101 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.
Remember! Attempts at self-repair by users of the LG 42LM580S TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!


SCHEMATIC DIAGRAM --------->  LG 42LM580S, 42LM580T, 42LM585S, 42LM580S, 42LM580T-ZA, 42LM585S-ZD Chassis LD21B.

PSU SCHEMATIC DIAGRAM --------->  LG EAY62608901 LGP4247L-12LPB PLDF-L103A


 To reduce the backlight current in LED drivers with the AAT2430AISX controller, increase the resistance of the resistor from terminal 50 (ISET) to the housing, for example, from 3 KOhm to 4.7 KOhm. Currents will proportionally decrease in each of the 16 channels. With a parallel connection of channels, currents are summed.


 The appearance of the MainBoard EAX64317403 is shown in the figure below:
EAX64317403
EAX64317403 can be used in TVs:
LG 32LM580S (Panel LC320EUN (SE)(F2)), LG 32LS5610 (Panel T320HVN01.0), LG 42LM580S ZA (Panel LC420EUE (SE)(F1)), LG 42LS5620 (Panel T420HVN01.1), LG 32LS5600 (Panel T320HVN01.0), LG 42LM585S -ZD (Panel LC420EUE (SE)(F1)).
PSU Advanced
The 42LM580S TV is equipped with an EAX64427101 power module using the PFC (Power Factor Correction) scheme acting as an active filter to eliminate the higher harmonic components of the current consumption. The boost converter based on the FAN7930BG PWM controller does not allow the input rectifier filter's electrolytic capacitor to be connected to the network directly through open diodes when the charge current determines its reactance (about 15-30 ohms at a frequency of 50 Hz). As a result of the conversion, the charging current of the capacitor will be determined in such a way that the envelope of the high-frequency pulses of the input current will repeat the phase and shape of the sine wave of the input voltage. The health check of the PFC unit is carried out by measuring the DC voltage on the capacitor of the rectifier network. In operating mode, it should be around 380V, in standby approximately 300V.
The appearance of the power supply
Main features of the device LG 42LM580S:
Installed matrix (LED-panel) LC420EUE (SE) (F1).
The matrix control uses the Timing Controller (T-CON) 6870C-0401B.
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by a PWM controller R5F100BCAFP, AAT2430AISX. As power elements of the LED driver, keys of the type PHT4NQ10LT * 4 are used.
The necessary supply voltages for all nodes of the LG 42LM580S TV are generated by the EAX64427101 power supply module or its analogs using FAN7930BG (PFC), L6599AD (PWM Resonant), STR-A6059 microchips and power switches of the STF13NM60N, STF10NM60N, FDT86106LZ type.
MainBoard - the main board (motherboard) is an EAX64317403 module using CPU chips: LGE2111A-T8, Nand: NAND01GW3B2CN6E, DDR: H5TQ1G63DFR-H9C, SPI Flash: W25Q80BV and others.
Tuner TDSQ-G001D - EBL61080101 provides the reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUE-SEF1
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 930.24x523.26 mm
Surface: Antiglare (Haze 1%), Hard coating (3H)
Brightness: 360 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6 (G to G)
Frequency: 60Hz
Lamp Type: 6 strings WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V