Wednesday, 26 February 2020

REPAIR / SERVICING TV LG 42LB652V

Technical description and composition of the LG 42LB652V TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LB652V 42LB652V-ZA.BRUWLJU
Chassis / Version: LC / LD / LE42B
Panel: LC420DUH (FG) (P2)
LED backlight: 3.0_42inch_Rev7_A-TYPE_131202, 3.0_42inch_Rev7_B-TYPE_131202
LED driver (backlight): integrated into PSU
PWM LED driver: BD9486F
Power Supply (PSU): EAX65423701 LGP3942-14PL1 3PCR00439B
PWM Power: MAP8800 (PFC), FA6A01N, NR134S
MainBoard: EAX65384003 (1.2) LC / LD / LE42B EBU62521902
IC MainBoard: CPU: LG1311, DRAM: H5TQ4G63AFR-PBC, EEPROM: AT24C256C, EMMC: THGBMAG6A2JBAIR
Tuner: TDJM-G101D EBL1400501
Control: Remote: AKB73756565, WIFI: LGSW41 EAT62093301 141852220029J
Specifications 42LB652V
LG 42LB652V
General repair guidelines for TV LCD LED
Possible malfunctions
- LG 42LB652V TV does not turn on. There are no signs of operability. The indicators on the front panel do not light or flash, the TV does not respond to the remote control and control buttons.
Often in such cases, the EAX65423701 power module is faulty. It is necessary to measure its output supply voltages, and in case of their absence, check the serviceability of the power switches of the converters and rectifier diodes for the probability of breakdown in PN semiconductor junctions.
In case of any breakdown of semiconductors in the secondary circuits, the converter can usually work normally in emergency short circuit mode. There are no output voltages. And with a short circuit in the power elements of the primary circuit, as a rule, the mains fuse breaks and less often the current sensor at the source of the key.
Mos-Fet power switches, used in switching power supplies, sometimes fail due to a malfunction of any other elements that can put it out of operation in key mode, or create an excess of the maximum permissible parameters of the switch. These can be elements supplying the PWM controller, frequency-setting or damping circuits, or negative feedback elements in the stabilization circuit. PWM controllers MAP8800 (PFC), FA6A01N, NR134S, in the absence of visible damage or explicit short-circuit between the terminals, are checked by replacing with new, or obviously working.
- 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.
In some of these cases, the malfunction is caused by a lack of backlighting on the display. The reason can be both in the power supply of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
When diagnosing, it is necessary to take into account that it is impossible to check the open in the chain of LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally, a current source. By opening the panel, each LED can be checked separately. Typically, Chinese multimeters light up a single 3-volt LED, if you connect probes in the forward direction to it. In dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of health. In the event of a LED malfunction, its zener diode will either be cut off or broken into short-circuit.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the EAX65384003 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). Board repair and replacement of CPU chips: LG1311, DRAM: H5TQ4G63AFR-PBC, EEPROM: AT24C256C, EMMC: THGBMAG6A2JBAIR are carried out 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 the TV works normally from external devices, but does not tune into television channels, the TDJM-G101D EBL1400501 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! For users and owners of 42LB652V TVs who do not have the appropriate qualifications, knowledge and experience, we categorically do not recommend attempting self-repair in order to avoid negative consequences that could lead to complete non-serviceability of the device.


schematic diagram ------------>  LG CHASSIS LD42B MODEL: 42LB65** 42LB65**-Z*.

 Backlight Current Limit:
In televisions with power supplies LGP3942-14PL1 (EAX65423701), the backlight current sensor - the resistor block R811-R818 consists of four pairs of 4.3 Ohm each. You can reduce the backlight current by 25% by removing one pair of resistors.


More details on this page


 The appearance of the MainBoard EAX65384003 is shown in the figure below:
EAX65384003
EAX65384003 can be used in TVs:
LG 47LB650V ZE (Panel LC470DUH (FG) (P2)), LG 42LB631V ZL (Panel LC420DUH (FG) (A1)), LG 39LB650V (Panel T390HVJ01.2), LG 55LB673V ZB (Panel LC550DUH (PG)(F1)), LG 47LB677V (Panel LC470DUH (FG)(F1)), LG 42LB673V (Panel LC420DUH (PG)(F1)), LG 47LB673V (Panel LC470DUH (PG)(F1)), LG 32LB652V 32LB652V-ZA.BRUWLDU (Panel LC320DUH (FG)(P2)), LG 50LB653V (Panel LC500DUH (FG)(P1)), LG 42LB652V 42LB652V-ZA.BRUWLJU (Panel LC420DUH (FG)(P2)), LG 55LB720V 55LB720V-ZG.BRUWLJU (Panel LC550DUH (PG)(F1)).
The appearance of the power supply
Main features of the device LG 42LB652V:
Installed matrix (LED-panel) LC420DUH (FG) (P2).
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the BD9486F PWM controller.
The necessary supply voltages for all nodes of the LG 42LB652V TV are generated by the EAX65423701 power module or its analogs using MAP8800 (PFC), FA6A01N, NR134S microcircuits.
MainBoard - the main board (motherboard) is an EAX65384003 module using CPU chips: LG1311, DRAM: H5TQ4G63AFR-PBC, EEPROM: AT24C256C, EMMC: THGBMAG6A2JBAIR and others.
Tuner TDJM-G101D EBL1400501 provides the reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUH-FGP2
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: 6/8 (Tr / Td)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V