Technical description and composition of the LG 42LM640T TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LM640T 42LM640S
Chassis / Version: LD22E
Panel: LC420EUG (PE) (F1) // LC420EUG (PE) (F2)
LED backlight: 6922L-0023A 401 (Cool); 42 ART TV REV 0.4 1 L-Type 6920L-0001C 6916L0948B; 42 ART TV REV 0.4 1 R-Type 6920L-0001C 6916L0947B
LED driver (backlight): integrated into PSU; 67.2V, 0.78A
PWM LED driver: UC2843BD1 (Step-Up LED), AAT2430AISX, R5F100BCAFP
MOSFET LED driver: STF19NF20, PHT4NQ10LT
Power Supply (PSU): EAX64744204 (1.3) (EAY62608903) LGP4247L-12LPB-3PM
PWM Power: L6599AD (PWM Resonant), FAN7930BG (PFC), STR-A6059H (Standby)
MOSFET Power: STF13NM60N (PFC), STF10NM60N
MainBoard: EAX64307906 (1.0)
IC MainBoard: CPU: LGE2112 1215-BTAH, NAND: KLM2G1HE3F-B001, Sound: STA380BWE
Tuner: TDSN-G351D
Control: Wi-Fi: TWFM-B003D EAT61613401; IR: LM66_76_96 Ver1.6
Specifications 42LM640T
LG 42LM640T
General repair guidelines for TV LCD LED
Diagnostics of malfunctions and repairs LG 42LM640T, as well as other electronic devices, it is recommended to start with an external examination of the external and internal elements. Often, based on certain external signs, it may be possible to draw certain conclusions about the reasons for the failure of certain elements of the circuit even before the necessary measurements are made, which will determine the further algorithm for troubleshooting and localizing the defect. Ring cracks in the soldering of the leads of the heating elements, swollen electrolytic capacitors, a charred paint layer on the resistors - all this for the repairman can be a significant clue in the assumptions about the causes and consequences of the malfunction.
In the case when the 42LM640T does not turn on, does not respond to the remote control and buttons on the front panel, does not blink light bulbs and does not show any signs of operability, the LGP4247L-12LPB-3PM, EAX64744204 (1.3) power supply module is faulty in this case (EAY62608903). If it is serviceable for such manifestations, it is necessary to check the stabilizer (converter) of the processor power supply on the motherboard.In diagnosing and repairing the power supply, first of all, replace the swollen capacitors of the secondary rectifier filter and check the fuse and, if it is broken, it is necessary to identify the cause. Often in such cases, an avalanche (thermal) breakdown is detected in the power semiconductor elements of the module — rectifier diodes and transistors in the primary circuit.
In most cases, key breakdowns in switching power supplies (SMPS) do not occur for no reason and you should look for other faulty circuit elements that could provoke a defect. This can be dried electrolytic capacitors in the primary circuit, and faulty damper elements, as well as dangling resistors or punched semiconductor elements in the stabilization circuits. Possible defective PWM chip from the manufacturer.
If the LG 42LM640T does not have an image, but there is sound, the backlight LEDs of the LC420EUG (PE) (F1) panel or their power converter may be malfunctioning. You should also make sure that the electrolytic capacitors of the secondary rectifiers of the common power supply are working.
A malfunction in the backlight circuits often occurs due to an open in the power circuit of the LED lines. It requires disassembling the panel and checking the LEDs themselves, the rations of their terminals, as well as the reliability of the connections in the connectors and rations of the terminals.
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.
Repair of the motherboard EAX64307906 (1.0) must begin with the diagnosis and verification of all linear stabilizers or power converters of its microcircuits. Sometimes it may be necessary to update the software (software) - flashing FLASH or EEPROM.
When repairing an MB board, you need to check its CPU components: LGE2112 1215-BTAH, NAND: KLM2G1HE3F-B001, Sound: STA380BWE. Defective items should be replaced. If BGA chips are installed, their malfunction is usually localized by heating.
The malfunction of the TDSN-G351D tuner is established after checking the software and all the supply voltages at its terminals.
Once again, remind users! Attempts to self-repair the LG 42LM640T TV without the appropriate qualifications and experience can lead to its complete non-repairability!
SCHEMATIC DIAGRAM ----------> LG Chassis LD22E 42LM640S/640T/649S/649T, 42LM640S/640T-ZA 42LM649S/649T-ZB SERVICE MANUAL.
PSU SCHEMATIC DIAGRAM ----------> EAX64744204 (EAY62608903) LGP4247L-12LPB-3PM
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 EAX64307906 is shown in the figure below:EAX64307906
EAX64307906 can be used in TVs:
LG 32LM640T ZA (Panel LC320EUA PE F2), LG 32LS570T (Panel LC320EUN (SE)(M2)), LG 47LM620S (Panel LC470EUE (SE)(F4)), LG 42LM670T (Panel LC420EUG(PE)(F2)), LG 42LM640T 42LM640S (Panel LC420EUG (PE)(F1)), LG 42LM620T (Panel LC420EUE (SE)(F1)), LG 47LM660T (Panel LC470EUG (PE)(F1)), LG 42LS570T (Panel T420HVN01.0), LG 42LS570S ZB (Panel LC420EUE (SE)(M1)), LG 42LM669T (Panel LC420EUG (PE)(F2)), LG 42LM669S (Panel LC420EUG (PE)(F1)), LG 37LM620T (Panel LC370EUN (SE)(F2)), LG 47LM669 (Panel LC470EUG (PE)(F2)), LG 32LS570S ZB (Panel LC320EUN (SE)(M2)), LG 47LM620T (Panel LC470EUE (SE)(F3)), LG 47LM761T ZA (Panel LC470EUH (PE)(F1), LG 32LM620S (Panel LC320EUN (SE)(F2) ), LG 47LM670T 47LM670T-ZA.BRUWLJU (Panel LC470EUG (PE)(F1)), LG 42LM660S 42LM660S-ZA.BRUWLJU (Panel LC420EUG (PE)(F1)), LG 42LM660T 42LM660T-ZA.BRUWLJU (Panel LC420EUG (PE)(F1) ), LG 32LM620T (Panel LC320EUN (SE)(F3)), LG 55LM620T 55LM620T-ZE (Panel LC550EUE (SE)(F1)).
PSU Advanced
According to the conditions of compliance with modern world standards for household switching power supplies, the EAX64744204 module provides for the use of a Power Factor Correction unit. The PFC circuit is a flyback converter based on the FAN7930BG 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 42LM640T:
Installed matrix (LED-panel) LC420EUG (PE) (F1) or LC420EUG (PE) (F2).
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by a PWM controller UC2843BD1 (Step-Up LED), AAT2430AISX, R5F100BCAFP. As the power elements of the LED driver, keys of the STF19NF20, PHT4NQ10LT type are used.
The necessary supply voltages for all nodes of the LG 42LM640T TV are generated by the EAX64744204 power supply module or its analogs using L6599AD (PWM Resonant), FAN7930BG (PFC), STR-A6059H (Standby) microcircuits and power switches of the STF13NM60N (PFC), STF10NM60N type.
MainBoard - the main board (motherboard) is an EAX64307906 module, using CPU chips: LGE2112 1215-BTAH, NAND: KLM2G1HE3F-B001, Sound: STA380BWE and others.
The TDSN-G351D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUG-PEF1
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 (2H)
Brightness: 360 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 8/10 (Tr / Td)
Frequency: 60Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V
