Technical description and composition of the LG 42LM3400 TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LM3400
Chassis / Version: LD21B / LC21B
Panel: LC420DUN (SE) (U2)
LED backlight: 42 ROW Rev0.8 2 R-TYPE 6916L-0913A; 42 ROW Rev0.8 2 L-TYPE 6916L-0882A, 6637L-0013A
T-CON: 6870C-0401C
LED driver (backlight): KLS-E420DRPHF02C, 6917L-0095C
PWM LED driver: BD9285F
MOSFET LED driver: AOD482, STC2073
Power Supply (PSU): EAX64604501 (1.5) - LGP32-12P
PWM Power: L6599AD (PWM Resonant), HS01G (PFC), FSL106HR (Standby DIP-8)
MOSFET Power: K10A60D, TK7P60V
MainBoard: EAX64317404 (1.0) G4_L_TU123
IC MainBoard: CPU: LGE2111A-T8, Nand: H27U1G8F2BTR, DDR: K4B1G1646G-BCK0, Spi: MX25L8006E
Tuner: TDSN-G301D
Control: IR EBR74561001, LM35-55
Specifications 42LM3400
LG 42LM3400
General repair guidelines for TV LCD LED
If the TV does not turn on, no control lights are on or blinking, there are no sounds when you turn on, and there is not the slightest sign of operability - the most likely malfunction is in the power module. 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 power semiconductor elements of the converter and the diode bridge of the rectifier network, as well as a large electrolytic capacitor of the filter of the rectifier network.
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 chip PWM L6599AD, HS01G, FCL106HR from the manufacturer.
If the LG 42LM3400 does not have an image, but there is sound, there may be a malfunction of the backlight LEDs of the LC420DUN (SE) (U2) panel or their power converter - LED driver.
To check the health of the LEDs and contact connections in their power circuit, the panel must be disassembled.
To check the health in the LED circuit, it is better to use a current source with a maximum voltage of 200V. We do not recommend using any voltage sources for this purpose. You can check each LED individually with a simple Chinese multimeter (powered by 9 volts) in the P-N-junction test mode. If you connect the red probe of the multimeter to the anode of the LED, and the black to its cathode, then the 3-volt LED will light up slightly, and in the opposite direction you can detect the transition of the emergency zener diode. A zener diode PN junction indirectly indicates a LED-a
Diagnosis and repair of the EAX64317404 (1.0) G4_L_TU123 motherboard usually begins with a test of the performance of the stabilizers and power converters of the module chips. In some cases, a software update is required.
In some cases, it is necessary to check or replace (if necessary) the elements of the MB board (SSB) - CPU: LGE2111A-T8, Nand: H27U1G8F2BTR, DDR: K4B1G1646G-BCK0, Spi: MX25L8006E. In cases where the BGA processor is used, its malfunction is usually detected by the local 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 TDSN-G301D 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.
Remember! Attempts to self-repair by users of the LG 42LM3400 TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!
SCHEMATIC DIAGRAM ---------> LG_CHASSIS : LD21C, MODEL : 42LM3400/340S/340T, 42LM3400/340S/340T-ZA SERVICE MANUAL.
PSU SCHEMATIC DIAGRAM ---------> LGP32-12P EAY62769501 EAX64604501 Power supply
The appearance of the MainBoard EAX64317404 is shown in the figure below:EAX64317404
EAX64317404 can be used in TVs:
LG 32LS560T (Panel LC320EUN (SE)(M2)), LG 42LS5600 (Panel T420HVN01.1), LG 47LM580T (Panel LC470EUE (SE)(U1)), LG 42LM3400 (Panel LC420DUN (SE)(U2)), LG 37LS560T (Panel LC370EUN (SE)(M2)), LG 32LM340T (Panel LC320DXN (SE)(U3)), LG 47LM615S (Panel LC470EUE (SE)(U1)), LG 32LM3400 32LM3400-ZA (Panel LC320DXN (SE)(U2)).
PSU Advanced
The 42LM3400 model uses the EAX64604501 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 step-up converter based on the HS01G 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 42LM3400:
Installed matrix (LED-panel) LC420DUN (SE) (U2).
The matrix control uses the Timing Controller (T-CON) 6870C-0401C.
To power the backlight LEDs, the KLS-E420DRPHF02C LED driver is used, controlled by the BD9285F PWM controller. As power elements of the LED driver, keys of the type AOD482, STC2073 are used.
The necessary supply voltages for all nodes of the LG 42LM3400 TV are generated by the EAX64604501 power supply module or its analogs using L6599AD (PWM Resonant), HS01G (PFC), FSL106HR (Standby DIP-8) microcircuits and power switches of the K10A60D, TK7P60V type.
MainBoard - the main board (motherboard) is an EAX64317404 module using CPU chips: LGE2111A-T8, Nand: H27U1G8F2BTR, DDR: K4B1G1646G-BCK0, Spi: MX25L8006E and others.
The TDSN-G301D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUN-SEU2
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: 300 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6 (G to G)
Frequency: 60Hz
Lamp Type: WLED Embedded (LED Driver)
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V