Technical description and composition of the LG 42LM620T TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LM620T
Chassis / Version: LD22 / LC22
Panel: LC420EUE (SE) (F1)
LED backlight: 6922L-0016A 6916L0936A 42 V12, 6920L-0001C
T-CON: 32/37/42/47/55 FHD TM120 VER0.2
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) P / N: EAY62608901 Model LGP4247L-12LPB
PWM Power: FAN7930BG (PFC), L6599AD (PWM Resonant), STR-A6059
MOSFET Power: STF13NM60N, STF10NM60N, FDT86106LZ
MainBoard: EAX64307906 (1.0)
IC MainBoard: CPU: LGE2112, H5TQ2G63BFR-PBC,
Tuner: TDSN-G351D
Control: IR: EBR74986703, LM35-55
Specifications 42LM620T
LG 42LM620T
General repair guidelines for TV LCD LED
Repair and diagnostics of any electronic device, in particular LG 42LM620T, it is advisable to start with a careful external examination of internal and external elements. 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. 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 42LM620T does not turn on, does not respond to the remote control and buttons on the front panel, does not blink bulbs and does not show any signs of operability, the LGP4247L-12LBP power supply module is probably defective in this case. If it is serviceable in such cases, it is necessary to check the stabilizer (converter) of the processor power supply on the motherboard.When diagnosing and repairing the power supply, first of all, replace the swollen filter capacitors of the secondary rectifiers 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.
It should be borne in mind that in the practice of repair it is extremely rare that key transistors in switching power supplies (SMPS) fail for no reason that should be sought by checking other components, for example, a breakdown of the key can provoke faulty elements of the damper circuits, or dried electrolytic capacitors or dangling primary resistors BP circuits involved in the stabilization process. In this case, all semiconductor elements of the strapping of the PWM controller chip are subject to verification, which it is desirable to verify by replacement.
Sometimes the LG 42LM620T TV does not have an image, but there is sound, or the image appears and immediately disappears. In this case, there is a high probability of a malfunction of the LC42EUE (SE) (F1) panel LED backlight converter, or a break in the LED circuit is possible. In such cases, first of all, it is necessary to verify the serviceability of all the electrolytic capacitors of the filter by supplying the LED driver itself, including in the power supply unit (power supply unit).
To check the health of the LEDs and contact connections in their power circuit, the panel must be disassembled.
When trying to identify a break in the LED lines, it should be borne in mind that it is difficult to do this without disassembling the panel. For example, a current source is needed to open PN junctions connected in series.
When trying to repair the motherboard, you should first check the serviceability of linear stabilizers or power converters of microcircuits and, if necessary, update the software (software).
In cases of complex repairs of MB (SSB) and in the presence of the necessary skills and equipment, sometimes it may be necessary to replace its CPU chips: LGE2112, H5TQ2G63BFR-PBC, and other possible faulty components. Malfunctions associated with the application of BGA soldering technologies are usually easily diagnosed by the heating method.
If there is no reception of television channels, but the TV is working properly from external devices, first of all you need to check the voltage of the TDSN-G351D tuner.
It should be remembered! Attempts to repair the LG 42LM620T 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: LD22E; 42LM620S/620T/625S, 42LM620S/620T-ZE, 42LM625S-ZG SERVICE MANUAL.
PSU SCHEMATIC DIAGRAM ----------> LG EAX64427101 EAY62608901 LGP4247L-12LPB PLDF-L103A.
LG 42LM620S-ZE.BEEWLJG; Panel: LC420EUE (SE)(F1), Main: EAX64307906(1.0) EBT62049202
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 42LM620T model uses the EAX64427101 power supply unit using the PFC (Power Factor Correction) node - an active filter of the highest harmonics of the current consumption. In fact, this is a boost converter based on the FAN7930BG PWM controller, which eliminates the charge current of the rectifier filter's electrolytic capacitor directly from the network through open diodes when its charging current is determined by its reactance.
As a result of the operation of the converter, the envelope of the high-frequency pulses of the input current of the converter will repeat the shape and phase of the input voltage. The health of the PFC node can be indirectly judged by the presence of an increased constant voltage (about + 380V) on the capacitor of the rectifier network in operating mode.
The appearance of the power supply
Main features of the device LG 42LM620T:
Installed matrix (LED-panel) LC420EUE (SE) (F1).
The matrix control uses the Timing Controller (T-CON) 32.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by a PWM controller R5F100BCAFP, AAT2430AISX. As the power elements of the LED driver, keys of the PHT4NQ10LT * 4 type are used.
The necessary supply voltages for all nodes of the LG 42LM620T TV are generated by the EAX64427101 power module or its analogs using FAN7930BG (PFC), L6599AD (PWM Resonant), STR-A6059 chips and power switches of the STF13NM60N, STF10NM60N, FDT86106LZ type.
MainBoard - the main board (motherboard) is an EAX64307906 module, using CPU chips: LGE2112, H5TQ2G63BFR-PBC, and others.
The TDSN-G351D tuner provides television reception and channel tuning.
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