Thursday, 27 February 2020

REPAIR / SERVICING TV LG 42LK451

Technical description and composition of the LG 42LK451 TV, panel type and applicable modules. The composition of the modules.
LG
Model: 42LK451 42LK451-ZG.BRUYLJU
Chassis / Version: LD01U // LD01M
Panel: T420HW09 V0 // V420H2-L05 Rev. C1 // LC420WUE (SC) (A2)
T-CON: T460HW03 VF CTRL BD. (46T03-C0K)
Inverter (backlight): 4H + V2988.141-A V298-C01 // T87I135.00 I420H2-12C-A002B
Power Supply (PSU): EAX63543801 9 - PSLH-L010A, 3PAGC10047A-R, LGP42-11P // EAX64743301 (1.1) LGP42-10LF
PWM Power: HS01G (PFC), ICE3BR4765JZ (Standby DIP-7), L6599AD
MOSFET Power: 10NM60N
MainBoard: EAX64290501 (0) - EBR73156231, SAA35246028, SAA35408714
IC MainBoard: CPU: LGE107DC-RP, DDR: H5TQ1G63DFR-PBC, NAND: 01GW3B2CN6E, SPI FLASH: 25Q80BVSIG
Tuner: TDTJ-S001D EBL60721201
Control: AKB72915244, IR: LW4500, LV2500, LK550_V1.7, (0X5431 VA.5)
Specifications 42LK451
LG 42LK451
General recommendations for repairing TV LCD
Any repair usually begins with an external inspection. In some cases, visible external damage to the elements can suggest the direction of troubleshooting and localization of the defect even before the start of the necessary measurements at the control points of the nodes of electronic circuits. Carbonized paint on the upper layer of resistors, electrolytic capacitors of rectifier filters swollen after boiling, cracked soldering at the terminals of heating elements or transformers can often suggest the cause of the defect and possible consequences.
If the power supply module EAX63543801 9 - PSLH-L010A, 3PAGC10047A-R, LGP42-11P malfunctions, the external manifestations may be different, for example, LG 42LK451 does not turn on at all and there is no indication of indicator lights on the front panel. In the general case, first of all, it is necessary to check the electrolytic capacitors of the secondary rectifier filters and the fuse at the input of the network. If it is cut off, then it is necessary to check the diodes of the rectifier bridge and the key transistor of the converter for a breakdown of the PN junctions, which can either be on a separate radiator or integrated with a PWM controller in a common chip. Possible options.
As a rule, the keys in switching power supplies (SMPS) are reliable enough and rarely fail for no reason to be looked for by checking other components of the circuit - electrolytic capacitors, resistors and semiconductor elements of the primary circuit. The PWM chip is verified by replacing it with a known good one.
If, when you turn on the TV, the image appears and immediately disappears, or is initially absent when turned on, but there are sound and other functions work, there is a high probability of a malfunction of the inverter (power converter for the backlight). In such cases, the lamps, the inverter and the common power module are subject to verification, in which the electrolytic capacitors of the rectifier filter feeding the inverter should be checked. When diagnosing a malfunction of the inverter with the protection off, special precautions must be taken, because there is a risk of failure of the power elements of the inverter. After the diagnosis, it is imperative to restore the protection circuits for the inverter to operate normally.
Repair or diagnostics of the motherboard EAX64290501 (0) - EBR73156231, SAA35246028, SAA35408714 should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, you should update the software (software). Often, the MB (SSB) card needs to be replaced in case of complex faults that are difficult to detect. When trying to repair, you should check its elements - CPU: LGE107DC-RP, DDR: H5TQ1G63DFR-PBC, NAND: 01GW3B2CN6E, SPI FLASH: 25Q80BVSIG and replace failed chips with new ones. Some malfunctions may be due to the use of BGA soldering technologies in modern Main Board technologies. Typically, such defects are detected by local heating of the chip.
If there is no reception of television channels, but the TV is working properly from external devices, first of all you need to check the voltage of the TDTJ-S001D EBL60721201 tuner and update the software. The pulses from the I2C bus must be controlled with an oscilloscope.
Attention to users! Self-repair of the LG 42LK451 TV without the appropriate qualifications and experience can lead to its complete non-repairability!


SCHEMATIC DIAGRAM --------->  LG CHASSIS LD01U; 32LK450, 32LK450A, 32LK450N, 32LK450U, 32LK451, 32LK450-ZB, 32LK450A-ZB, 32LK450N-ZB, 32LK450U-ZB, 32LK451-ZAB

 The appearance of the MainBoard EAX64290501 is shown in the figure below:
EAX64290501
EAX64290501 can be used in TVs:
LG 32LV2500-ZA (Panel T315XW06 V.3), LG 37LV3500-ZA (Panel T370HW05 V.1), LG 42LV3400-ZA (Panel T420HW08 V.1), LG 32LK530 (Panel LC320WUD (SC)(A3)), LG 37LK430 (Panel LC370WUE), LG 32LK451 ZA (Panel T315HW04 V.9), LG 42LV3551 (Panel LC420EUN (SD) (V3)), LG 47LW4500 (Panel LC470EUF (SD)(F2)), LG 32LK551 ZB (Panel LC320WUD (SC)(A2)), LG 42LV3500 (Panel LC420EUN (SD)(V3)), LG 42LK551 ZB (Panel V420H2-LH5), LG 42LK451 42LK451-ZG.BRUYLJU (Panel T420HW09 V0), LG 42LK530 (Panel LC420WUF (SC)(A2)), LG 47LK950 ZA (Panel LC470WUF (SD)(P1)), LG 32LW4500 ZB (Panel LC320EUD (SD)(P1)), LG 42LW4500 ZB (Panel LC420EUF (SD)(PX)), LG 42LV4500 DA (Panel LC420EUF (SD)(A1)), LG 32LV4500 (Panel LC320EUD (SD)(A4)), LG 42LV369C (Panel T420HW08 V.9).
PSU Advanced
The EAX63543801 power supply module is made using the Power Factor Correction (PFC) scheme to eliminate multiple AC harmonics introduced into the power supply by the device. The PFC is a Step-Up Converter based on the HS01G PWM controller, which evenly distributes high-frequency impulses of the charging current of the electrolytic capacitor of the rectifier filter of the mains voltage evenly over a period of 50 Hz. The current of its charge in this case will already be determined not by its reactance (usually 10-30 ohms for the network frequency), but by the elements of the converter. As a result, a change in the amplitude of the pulses (envelope) of the consumed current of the converter will repeat the shape and phase of the input sinusoidal voltage. The availability of an increased voltage (about + 380V) in the operating mode on the capacitor of the line filter indicates the serviceability of the PFC node.
The appearance of the power supply
Main features of the device LG 42LK451:
Installed matrix (LCD panel) T420HW09 V0 or V420H2-L05 Rev. C1 or LC420WUE (SC) (A2).
The matrix control uses the Timing Controller (T-CON) T460HW03.
To power the backlight, an inverter 4H + V2988.141-A is used.
The necessary supply voltages for all nodes of the LG 42LK451 TV are generated by the EAX63543801 power supply module or its analogs using HS01G (PFC), ICE3BR4765JZ (Standby DIP-7), L6599AD microcircuits and 10NM60N power switches.
MainBoard - the main board (motherboard) is an EAX64290501 module, using CPU chips: LGE107DC-RP, DDR: H5TQ1G63DFR-PBC, NAND: 01GW3B2CN6E, SPI FLASH: 25Q80BVSIG and others.
The TDTJ-S001D EBL60721201 tuner provides TV reception and channel tuning.