Technical description and composition of the LG 42LV370S TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LV370S
Chassis / Version: LD12B
Panel: LC420EUN (SD) (V5)
Power Supply (PSU): EAX63729001 / 7
PWM Power: FAN7930B (PFC), 3BR4765JZ (Standby DIP-7), L6599AD (PWM Resonant)
MOSFET Power: K10A60D
MainBoard: EAX63557704 (0)
IC MainBoard: CPU: LGE35230, Nand: TC58DVG3S0ETA, DDR: K4B2G1646C
Tuner: TDFQ-G001D
Specifications 42LV370S
LG 42LV370S
General repair guidelines for TV LCD LED
Repair of the LG 42LV370S TV is advisable to start with a careful external examination of both internal and external elements. Visible damage to elements can sometimes indicate the direction of the search for a defect even before the necessary measurements are taken. Electrolytic capacitors of filters with a swollen casing, as well as ring cracks formed in the soldered leads of heating elements, or a layer of coal on burnt resistors sometimes tell the repairman the causes of the malfunction 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 EAX63729001 / 7 power supply module is defective 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. First of all, it is necessary to replace the swollen capacitors of the rectifier filters, if any. If the mains fuse is broken in the power supply, in most cases a breakdown of the power key (s) is detected, which can be integrated with the PWM controller, or a separate field-effect transistor can be used. The rectifier bridge diodes and the electrolytic capacitor of the mains rectifier filter should also be checked.
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 circuit.
If the LG 42LV370S does not have an image, but there is sound and the TV is controlled by the remote control, a malfunction in the backlight circuits of the LC420EUN (SD) panel (V5) is likely. The LEDs or the power converter - LED driver may be faulty. Often in such cases, when you turn on the TV, an image appears and immediately disappears. First of all, it is necessary to verify the operability of the electrolytic capacitors of the rectifier filter supplying the LED driver, and check the LEDs, connecting obviously known good diagnostics.
To check the health of the LEDs, as well as contact connections in the ruler circuit, it is necessary to disassemble the panel.
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.
On the EAX63557704 (0) motherboard, in case of a malfunction, you should first check the performance of all stabilizers or power converters of the microcircuits and, if necessary, update the software (software).
If it is not possible to replace the MB (SSB) card, you need to check the health of its elements - CPU: LGE35230, Nand: TC58DVG3S0ETA, DDR: K4B2G1646C. Defective components should be replaced.
If a TDFQ-G001D tuner is suspected to be malfunctioning, first of all, it is necessary to verify that there is a supply voltage at the corresponding output of the tuner.
For owners of the 42LV370S 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 ----------> LG Chassis LD12B 42LV3700/370S, 42LV3700/370S-ZC, 42LV375G/S/W, 42LV375G/S/W-ZC SERVICE MANUAL
The appearance of the MainBoard EAX63557704 is shown in the figure below:EAX63557704
EAX63557704 can be used in TVs:
LG 37LV370S (Panel T370HW05 V.1), LG 42LV370S (Panel LC420EUN (SD) (V5)), LG 32LV3700 (Panel T315HW07 V.8), LG 42LV3700 (Panel LC420EUN (SD)(V3)), LG 47LV370S ZB (Panel LC470EUE (SD)(V1)), LG 32LV370S (Panel T315HW07 V.8).
PSU Advanced
On the 42LV370S TV, the EAX63729001 / 7 power module is installed using the PFC (Power Factor Correction) scheme acting as an active filter to eliminate the higher harmonic components of the current consumption. The boost converter based on the FAN7930B PWM controller does not allow the input rectifier filter's electrolytic capacitor to be connected directly to the network directly through open diodes, when the value of the charge current determines its reactance (about 15-30 ohms at a frequency of 50 Hz). As a result of the conversion, the charging current of the capacitor will be determined in such a way that the envelope of the high-frequency pulses of the input current will repeat the phase and shape of the sine wave of the input voltage. The health check of the PFC unit is carried out by measuring the DC voltage on the capacitor of the rectifier network. In operating mode, it should be around 380V, in standby approximately 300V.
The appearance of the power supply
Main features of the device LG 42LV370S:
Installed matrix (LED-panel) LC420EUN (SD) (V5).
The necessary supply voltages for all nodes of the LG 42LV370S TV are generated by the EAX63729001 power module or its analogs using FAN7930B (PFC), 3BR4765JZ (Standby DIP-7), L6599AD (PWM Resonant) microcircuits, and K10A60D type power switches.
MainBoard - the main board (motherboard) is an EAX63557704 module using CPU chips: LGE35230, Nand: TC58DVG3S0ETA, DDR: K4B2G1646C and others.
The TDFQ-G001D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUN-SDV5
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 10%), Hard coating (3H)
Brightness: 360 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M (8-bit)
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