Technical description and composition of the LG 42LA620V TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LA620V
Chassis / Version: LD33B
Panel: LC420DUE (SF) (U1)
LED backlight: 6916L-1412A, 6916L-1414A, 6916L-1413A, 6916L-1415A
T-CON: LC500DUE-SFR1 6870C-0452A
LED driver (backlight): integrated into PSU; 105V 313mA
PWM LED driver: BD9483F
MOSFET LED driver: KF9N25
Power Supply (PSU): EAX64905401 (1.5)
PWM Power: SSC9527S (PWM Resonant), R2A20133D (PFC), 3BR4765JZ (Standby)
MOSFET Power: TK8P60V, K10A60W (PFC)
MainBoard: EAX64797003 (1.2)
IC MainBoard: CPU: LGE2122, NAND: SAA36403538 VER. 3.20.33 H5TQ4G63AFR x2 H5TQ2G63AFR NTP7513
Tuner: TSQ-G601D (B) EBL61240503
Specifications 42LA620V
LG 42LA620V
General repair guidelines for TV LCD LED
LG 42LA620V, like other televisions, it is advisable to start repairing with a careful examination of the external and internal elements and modules. Many visible changes in the state of the elements make it possible to determine the further direction of troubleshooting and localization of the defect. Carbonized paint on the upper layer of resistors, electrolytic capacitors of rectifier filters swollen after boiling, cracked soldering at the terminals of heating elements or transformers can often suggest the cause of the defect and possible consequences.
If the TV does not turn on, no indicators on its front panel are lit or blinking. Also, if the TV does not respond to the remote control and buttons, does not make any sounds or any signs of operability when turned on, there is a certain chance that the EAX64905401 power supply module (1.5) is faulty and needs repair. Sometimes with similar manifestations a problem can only occur in the absence of processor power, which is typical for certain LG models. Diagnostics and repair of the common power supply should always begin with a check of the mains fuse and the condition of the electrolytic capacitors of the secondary rectifier filters. Defective and swollen capacitors should be replaced with new ones. If the fuse breaks, it is advisable to check for a breakdown, first of all, all the power semiconductor elements of the converter and the diode bridge of the rectifier network, as well as the large electrolytic capacitor of the filter of the rectifier network.
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 PWM controller chip itself may be faulty. It is also necessary to check all the semiconductor elements of the stabilization circuit in the primary and secondary circuits.
If there is no image when you turn on the LG 42LA620V, or it appears for a second and disappears, but there is sound, there is most likely a malfunction in the backlight LED circuit of the LC420DUE (SF) (U1) panel, or in their power converter. It is necessary to check the electrolytic capacitors of the filter of the secondary rectifiers in the general power supply unit.
To check the health of the LEDs, as well as contact connections in the ruler circuit, it is necessary to disassemble the panel.
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.
The motherboard EAX64797003 (1.2) must be checked 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.
Board repair and replacement of CPU chips: LGE2122, NAND: SAA36403538 VER. 3.20.33 H5TQ4G63AFR x2 H5TQ2G63AFR NTP7513 are manufactured with 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 you suspect a malfunction of the TSQ-G601D (B) EBL61240503 tuner, first of all, make sure that there is a supply voltage at the corresponding output of the tuner.
Schematic diagram ------------> LG CHASSIS: LD33B; 42LA62**, 42LA62**-Z* SERVICE MANUAL.
Once again, we remind TV users: you should not make attempts to repair it yourself without the appropriate knowledge, experience and the necessary qualifications! Trust the repair only to professionals with sufficient experience in the field of electronic equipment repair.
Schematic diagram ------------> EAX64905401 LGP42-13R2 Power Supply schematic diagram
You can limit the backlight current in TVs with LGP42-13R2 power supplies (EAX64905401) by increasing the resistance of the current sensors R811-R818 - channel 1 and R829-R836 - channel 2. All resistors are in pairs of 4.3 Ohm. To reduce the backlight current by 25%, one pair of resistors in each channel should be removed.
The appearance of the MainBoard EAX64797003 is shown in the figure below:EAX64797003
EAX64797003 can be used in TVs:
LG 42LA620V (Panel LC420DUE (SF)(U1)), LG 32LN570V (Panel LC320DUE (SF)(R1)), LG 50LA644V (Panel LC500EUN (SF)(F1)), LG 47LA660V (Panel LC470EUG (PF)(F1)), LG 47LA621V (Panel LC470DUE (SF)(U1)), LG 42LA644V (Panel LC420EUN (SF)(F2)), LG 39LA620V ZA (Panel T390HVJ01.0), LG 42LA621V ZD (Panel LC420DUE (SF)(U1)), LG 32LA621V ZD (Panel LC320DUE (SF)(U1)), LG 32LN655V (Panel LC320EUB (PF)(M1)), LG 42LA667V (Panel LC420EUH (PF)(P1) ), LG 47LN613V (Panel LC470DUE (SF)(R4)), LG 32LA667V ZB (Panel LC320EUB (PF)(P1)), LG 55LA660V ZA (Panel LC550EUH (PF)(P1)), LG 47LA620V ZA (Panel LC470DUE (SF)(U1)), LG 32LN613V ZB (Panel LC320DUE (SF)(R4)), LG 42LN655V ZB.BRUZLJU (Panel LC420EUH (PF)(M1)), LG 32LA644V ZA (Panel LC320EUN (SF)(F1)), LG 42LN613V (Panel LC420DUE (SF)(R4)), LG 47LA690V ZB (Panel LC47EUH (PF)(P1)), LG 47LA662V (Panel LC470EUG (PF)(F1)), LG 42LA645V 42LA645V-ZC.BRUYLJU (Panel LC420EUN (SF)(F3)), LG 32LA660V (Panel LC320EUB (PF)(P1)), LG 47LA644V 47LA644V-ZA (Panel LC470EUN (SF)(F2)), LG 50LA667S (Panel T500HVD02.1), LG 47LA691V (Panel LC470EUH (PF)(P1)), LG 32LA662V (Panel LC320EUB (PF)(P1)).
PSU Advanced
The 42LA620V model uses the EAX64905401 power supply unit using the PFC (Power Factor Correction) node - an active filter of the highest harmonics of the current consumption. In fact, it is a boost converter based on the R2A20133 PWM controller, which eliminates the charge current of the electrolytic capacitor of the rectifier filter 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 42LA620V:
Installed matrix (LED-panel) LC420DUE (SF) (U1).
The matrix control uses the Timing Controller (T-CON) LC500DUE-SFR1.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the BD9483F PWM controller. As the power elements of the LED driver, keys of the KF9N25 type are used.
The necessary supply voltages for all nodes of the LG 42LA620V TV are generated by the EAX64905401 power supply module or its analogs using SSC9527S (PWM Resonant), R2A20133D (PFC), 3BR4765JZ (Standby) microcircuits, and TK8P60V, K10A60W (PFC) type power switches.
MainBoard - the main board (motherboard) is an EAX64797003 module using CPU chips: LGE2122, NAND: SAA36403538 VER. 3.20.33 H5TQ4G63AFR x2 H5TQ2G63AFR NTP7513 and others.
The tuner TSQ-G601D (B) EBL61240503 provides the reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUE-SFU1
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 (2H)
Brightness: 300 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6 (G to G)
Frequency: 60Hz
Lamp Type: 2 strings WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V
