Technical description and composition of the LG 42LA621V TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LA621V ZD
Chassis / Version: LB33E / LE33E / LC33E
Panel: LC420DUE (SF) (U1)
LED backlight: 6916L-1412A, 6916L-1413A, 6916L-1414A
T-CON: LC500DUE-SFR1 6870C-0452A
LED driver (backlight): integrated into PSU; 70-135V 313mA
PWM LED driver: BD9483F
MOSFET LED driver: KF9N25
Power Supply (PSU): EAX64905401 (1.5) LGP42-13R2
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, H5TQ2G63AFR, NTP7513
Tuner: TSQ-G601D (B) EBL61240503
Control: Wi-Fi: EAT61813901 (TWFM-B006D)
Specifications 42LA621V
LG 42LA621V
General repair guidelines for TV LCD LED
In the case when the 42LA621V does not turn on, does not respond to the remote control and the front panel buttons, does not blink bulbs and does not show any signs of operability, the EAX64905401 (1.5) LGP42-13R2 power supply module is probably defective in this case. 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.
Power switches in pulsed power supplies (SMPS) fail extremely rarely for no reason and, if they are broken, it is necessary to look for a malfunction in the stabilization circuits by checking electrolytic capacitors, semiconductor devices, and resistors in the primary circuit. The reason may be a malfunction of the PWM controller chip SSC9527S, R2A20133 (PFC), 3BR4765JZ (Standby), which can only be checked by replacing it with a new or obviously working one.
Sometimes the LG 42LA621V TV does not have an image, but there is sound, or the image appears and immediately disappears. In this case, there is a possibility of a malfunction of the LED driver - power converter for the backlight LEDs of the LC420DUE (SF) panel (U1), or a break in the LED circuit is possible. In such cases, first of all, it is necessary to verify the operability of the electrolytic capacitors of the filter by supplying the backlight unit.
In case of breaks in the LED circuit, a complete disassembly of the panel is required, the LEDs are checked for an open circuit, as well as the reliability of the connections in the connectors and rations of the terminals.
To check the LED lines for breaks without disassembling the panel, for example, a current source will help. It is impossible to open series-connected PN junctions with a simple multimeter, a voltage of the order of several tens of volts is required.
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.
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: LGE2122, NAND: SAA36403538 VER. 3.20.33, H5TQ4G63AFR, H5TQ2G63AFR, NTP7513 and other possible defective components. Malfunctions associated with the application of BGA soldering technologies are usually easily diagnosed by the heating method.
In the absence of tuning to the channels of on-air or cable television, you should make sure that the software is correct, as well as in accordance with the ratings of the supply voltage at the terminals of the TSQ-G601D (B) EBL61240503 tuner. It is also necessary to check the presence of pulses of data exchange between the tuner and the processor via the I2C bus using an oscilloscope.
Attention to the owners! Attempts to repair the LG 42LA621V TV independently are not recommended by the manufacturer and can lead to serious negative consequences.......
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 42LA621V 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 42LA621V:
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 42LA621V TV are generated by the EAX64905401 power supply module or its analogs using SSC9527S (PWM Resonant), R2A20133D (PFC), 3BR4765JZ (Standby) microcircuits and power switches of the TK8P60V, K10A60W (PFC) type.
MainBoard - the main board (motherboard) is an EAX64797003 module using CPU chips: LGE2122, NAND: SAA36403538 VER. 3.20.33, H5TQ4G63AFR, 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