Technical description and composition of the LG 42LM670T TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LM670T
Chassis / Version: LD22E
Panel: LC420EUG (PE) (F2)
T-CON: TPS65178, TPS65198
LED driver (backlight): integrated into PSU; 67.2V, 0.78A
PWM LED driver: UC2843BD1 (Step-Up LED), AAT2430AISX, R5F100BCAFP
MOSFET LED driver: STF19NF20, PHT4NQ10LT * 6
Power Supply (PSU): EAX64744201 LGP4247L-12LPB-3P, (EAY62608902)
PWM Power: L6599AD (PWM Resonant), FAN7930BG (PFC), STR-A6059H (Standby)
MOSFET Power: STF13NM60N * 2, STF10NM60N * 2
MainBoard: EAX64307906 (1.0)
IC MainBoard: CPU: LGE2112 1215-BTAH, NAND: KLM2G1HE3F-B001, Sound: STA380BWE
Tuner: TDSN-G351D EBL61080002
Specifications 42LM670T
LG 42LM670T
General repair guidelines for TV LCD LED
Repair of the LG 42LM670T TV should begin with a fault diagnosis, which involves a careful examination of the external and internal elements of the device. Sometimes, based on visible changes in the components of the device, it is possible to draw some conclusions and determine the direction of further troubleshooting, even before the necessary measurements are taken. In some cases, faulty elements can be seen with the naked eye, for example, charred resistors or swollen metal-ceramic capacitors, or electrolytic in rectifier filters. Ring cracks formed in the soldered terminals of transformers or heating elements of the circuit are also frequent sources of many malfunctions with a variety of external manifestations.
In the absence of any signs of operability, when the LG 42LM670T does not turn on and does not signal anything with the control lights on the panel, there is a possibility of a malfunction of the power supply module LGP4247L-12LPB-3P, EAX64744201 (EAY62608902) of the TV. With the same manifestations, the power regulator of the control processor on the motherboard may be faulty. In the absence of swollen filter capacitors of the secondary rectifiers, the diagnostics of the power supply should begin 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.
As a rule, the keys in switching power supplies (SMPS) are reliable enough and rarely fail for no reason to be looked for by checking other components of the circuit - electrolytic capacitors, resistors and semiconductor elements of the primary circuit. The PWM chip is verified by replacing it with a known good one.
If the LG 42LM670T has no image, there is sound and the channels are switched, there is a possibility of a malfunction in the backlight LED circuit of the LC420EUG (PE) (F2) panel, or their power converter - LED driver. Sometimes when you turn on the image appears and disappears immediately. In such cases, it is necessary to check the electrolytic capacitors of the power filter of the LED driver itself, including in the secondary rectifier of the main PSU.
Often there is a need for disassembling the panel to check the health of the LEDs, as well as contact connections in the connectors and soldering.
It is impossible to detect a break in the LED line without disassembling the panel with a simple multimeter. The LEDs are connected in series and to open their transitions, a voltage of several tens of volts is required. Ideally, a current source is suitable for such purposes.
The EAX64307906 (1.0) motherboard is subject to verification if there is no reaction to the remote control and function buttons, the standby indicator blinks or lights up continuously. In such cases, if the converters or power regulators of the microcircuit are working, a software update may be necessary.
Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU: LGE2112 1215-BTAH, NAND: KLM2G1HE3F-B001, Sound: STA380BWE and replace failed chips with new ones. Some malfunctions can be associated with the use of BGA soldering technologies in modern Main Board. Typically, such defects are detected by local heating of the chip.
Before changing the TDSN-G351D EBL61080002 tuner, if it is not possible to tune to television channels, make sure that there are supply voltages, including varicap power (30-33V), which must be measured on the corresponding tuner pins.
For owners of the 42LM670T TV, we recommend that you contact qualified personnel with experience to repair! Self-repair attempts without the appropriate knowledge and skills can lead to serious negative consequences!
SCHEMATIC DIAGRAM ----------> LGP4247L-12LPB-3P - EAY62608902 - PLDF-L103B - EAX64744201 (1.3 - 1.5).
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
The EAX64744201 power supply module is made using the Power Factor Correction (PFC) scheme to eliminate multiple AC harmonics introduced into the power supply by the device. The PFC is a Step-Up Converter based on the FAN7930BG PWM controller, which evenly distributes high-frequency pulses of the charging current of the electrolytic capacitor of the mains rectifier filter across a 50 Hz period. 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 42LM670T:
Installed matrix (LED-panel) LC420EUG (PE) (F2).
The matrix control uses the Timing Controller (T-CON) TPS65178.
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 power elements of the LED driver, keys of the type STF19NF20, PHT4NQ10LT * 6 are used.
The necessary supply voltages for all nodes of the LG 42LM670T TV are generated by the EAX64744201 power supply module or its analogs using L6599AD (PWM Resonant), FAN7930BG (PFC), STR-A6059H (Standby) microchips and power switches of the STF13NM60N * 2, STF10NM60N * 2 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 EBL61080002 tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUG-PEF2
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: 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: 1.06B (8-bit + FRC), CIE1931 68%
Response Time: 6/8 (Tr / Td)
Frequency: 60Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V