Technical description and composition of the LG 42LV770S TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LV770S 42LV770
Chassis / Version: LD12D / E
Panel: LC420DUC (SD) (S1)
LED driver (backlight): 6917L-0057A PPW-LE42AF-M
Power Supply (PSU): EAX62876101 LGP4247-11SPH EAY62169601
PWM Power: 3BR4765J (Standby)
MainBoard: EAX64405401 (0) EBT61757305 (EBT61757304)
IC MainBoard: LGE35230, M24C16, K4B2G1646C-HCKO, TH58DVG4S0ETA20, NTP7400L, F0514A
Tuner: TDFR-G256D
Specifications 42LV770S
LG 42LV770S
General repair guidelines for TV LCD LED
Possible malfunctions
- LG 42LV770S does not turn on, the indicators on the front panel do not light or flash. The TV does not respond to the control buttons and the remote control.
Most often, with such manifestations, the main power supply module EAX62876101 is found to be faulty. It is then necessary to measure its output voltages and, if they are absent, it is necessary to check the power switches and rectifier diodes of the converters for a short-circuit probability.
In case of breakdowns of semiconductors in secondary circuits, the converter can usually operate abnormally in short circuit mode, and during short circuit in the power elements of the primary circuit, the main fuse often breaks.
Breakdown of power switches (MosFet) in pulsed sources is sometimes caused by malfunctions of other circuit elements, for example, in circuits supplying a PWM controller, frequency-setting or damper ones, as well as in negative feedback (OOS) stabilization circuits. PWM controllers (PWM) 3BR4765J (Standby), if they do not have visible damage to the case and open fault between the terminals, are usually checked by replacement.
- There is no image, there is sound, it responds to the remote control, the channels are switched. In some cases, the image appears when you turn on and immediately disappears.
A malfunction is usually most likely in these cases at the backlight nodes of the display matrix. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To check the LED strips, to open all the transitions of the LEDs, several tens of volts or more are needed, it is best to use a current source for such purposes. The breakage of several PN junctions connected in series cannot be detected with a multimeter or tester. In such cases, it is necessary to open the panel and check each LED. If your multimeter cannot open the LED transitions in forward bias, you can sometimes detect the presence of a PN junction of the protective zener diode by connecting the probes in the opposite direction. If the zener diode is broken or broken in short-circuit, then the LED is faulty and needs to be replaced.
- The TV does not turn on, the indicator indicates standby or operating mode, or blinks.
Repair or diagnostics of the EAX64405401 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). When repairing an MB board, you need to check its components LGE35230, M24C16, K4B2G1646C-HCKO, TH58DVG4S0ETA20, NTP7400L, F0514A. Defective items should be replaced. If chips with BGA soldering technology are used, a problem in its implementation is detected by the local heating of the chip.
If the TV works normally from external devices, but does not tune into television channels, the TDFR-G256D tuner may be malfunctioning. In such cases, first of all, you should make sure that there are supply voltages at its corresponding conclusions. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus. Sometimes the cause of the inoperability of the tuner may be a software failure.
Attention! Users and owners of 42LV770S TVs who do not have the appropriate qualifications, knowledge and experience are strongly advised against self-repair attempts in order to avoid negative consequences that could lead to complete non-repairability of the device.
The appearance of the MainBoard EAX64405401 is shown in the figure below:EAX64405401
EAX64405401 can be used in TVs:
LG 32LV571S (Panel LC320EUD (SD) (F3)), LG 42LV571S ZA (Panel LC420EUF (SD) (A1)).
Main features of the device LG 42LV770S:
Installed matrix (LED-panel) LC420DUC (SD) (S1).
To power the backlight LEDs, the 6917L-0057A LED driver is used.
The necessary supply voltages for all nodes of the LG 42LV770S TV are generated by the EAX62876101 power module, or its analogs using 3BR4765J (Standby) microcircuits.
MainBoard - the main board (motherboard) is an EAX64405401 module using LGE35230, M24C16, K4B2G1646C-HCKO, TH58DVG4S0ETA20, NTP7400L, F0514A, and others microcircuits.
The TDFR-G256D tuner provides television reception and channel tuning.