Friday, 28 February 2020

REPAIR / SERVICING TV LG 42LN540V

Technical description and composition of the LG 42LN540V TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LN540V
Chassis / Version: LD31B / LC36B / LL36B
Panel: LC420DUE (SF) (R1) // LC420DUE (SF) (R3)
LED backlight: Led 42 ROW2.1 Rev 0.6 6916L-1214A, 6916L-1215A, 6916L-1216A, 6916L-1217A
T-CON: LC5000UE-SFR1 6870C-0452A
LED driver (backlight): integrated into PSU; 157V 341mA
PWM LED driver: MAP3202
MOSFET LED driver: FDT86106, STF10NM60N
Power Supply (PSU): EAX64905301 (2.3) REV 3.0
PWM Power: SSC1S311A (PWM flyback), NR891D (PWM Step-down 24/12)
MOSFET Power: MDF11N65B
MainBoard: EAX64891306 (1.1)
IC MainBoard: CPU: LGE-2121-MS, Spi Flash: MX25L8005
Tuner: TDSQ-G601D
Control: AKB73715603
Specifications 42LN540V
LG 42LN540V
General repair guidelines for TV LCD LED
TV LG 42LN540V, like many other electronic devices, it is advisable to start repairing by inspecting all external and internal elements. Many visible changes in the state of the elements make it possible to determine the further direction of troubleshooting and localization of the defect. If charred resistors, swollen electrolytic or cermet capacitors, ring cracks in the soldered terminals of transformers or heating elements are detected, it is advisable to establish the causes and consequences of the malfunction that has arisen, as well as to check the connected elements and assemblies.
If the 42LN540V TV does not turn on, does not make any sounds when it is turned on, and also no indicators on the front panel light or blink - there is a high probability of a malfunction in the power supply module. In some cases, only the stabilizer or power converter of the control processor may be malfunctioning, which is typical for some LG models. In the absence of swollen filter capacitors of the secondary rectifiers, the diagnostics of the power supply should begin by checking the fuse and, if it is broken, it is first necessary to check all the power semiconductor elements of the primary circuit - diodes and transistors for the possibility of an avalanche or thermal breakdown.
The reasons for the breakdown of the power switch in switching power supplies (IIPS) can be different, for example, a malfunction of semiconductor cells or electrolytic capacitors in the stabilization circuits of the primary circuit, as well as a failure in the operation of the PWM controller IC IC011-SSC1S311, IC801-MAP3202, IC802-NR891D or breakage of resistors in its harness.
If the LG 42LN540V has no image, there is sound and the channels are switched, there is a possibility of a malfunction in the backlight LED circuit of the LC420DUE panel, or their power converter - LED driver. Sometimes when you turn on the image appears and disappears immediately. In such cases, it is necessary to check the electrolytic capacitors of the power filter of the LED driver itself, including in the secondary rectifier of the main PSU.
To check the health of the LEDs, as well as contact connections in the ruler circuit, the panel must be disassembled.
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.
Repair of the EAX64891306 motherboard (1.1) should begin with the diagnosis and verification of all linear stabilizers or power converters of its microcircuits. Sometimes it may be necessary to update the software (software) - flashing FLASH or EEPROM.
Sophisticated MB board repair (SSB) is in some cases possible and practiced by repairmen. To do this, check and, if necessary, replace the CPU elements: LGE-2121-MS, Spi Flash: MX25L8005. BGA chip malfunctions are usually easy to detect by warming up.
The malfunction of the TDSQ-G601D tuner is established after checking the software and all the supply voltages at its terminals.
Remember! Attempts at self-repair by users of the LG 42LN540V TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!





  SCHEMATIC DIAGRAM ----------> 
LG 42LN54XX 42LN540S 42LN540V 42LN541V 42LN542V (CHASSIS LD31B LD36B).


 PSU SCHEMATIC DIAGRAM ---------->  LG 37/39/42 Inch LGP3739-13PL1, LGP42-13PL1


 
FIRMWARE SPI FLASH LG 42LN540V, Main: EAX64891306(1.1), Panel: LC420DUE


 The appearance of the MainBoard EAX64891306 is shown in the figure below:
EAX64891306
EAX64891306 can be used in TVs:
LG 32LN540V (Panel LC320DUE (SF)(R1)), LG 42LN542V-ZD (Panel LC420DUE SFR3), LG 32LN541V (Panel LC320DUE (SF)(R1)), LG 42LA615V (Panel LC420DUE (SF)(U2) ), LG 32LA615V (Panel LC320DUE (SF)(U2)), LG 42LN540V (Panel LC420DUE (SF)(R1)), LG 42LN541V (Panel LC420DUE (SF)(R1)), LG 47LN540V (Panel LC470DUE (SF)(R1)), LG 32LB530U ZA (Panel LC320DXE (SG)(R1)), LG 39LN540V (Panel HC390DUN-VCFP1-11XX), LG 32LA643V (Panel LC320EUN (SF)(F1)), LG 32LN542V (Panel LC320DUE SF R1), LG 47LA615V (Panel LC470DUE (SF)(U2)), LG 47LA643V ZB (Panel LC470EUN (SF)(F2)), LG 32LN541U ZB (Panel HC320DXN-VHFP1 - 21XX / HC320DXN-VHFPA - 21XX), LG 32LN536U (Panel NC320DXN (SA)(P1)), LG 37LN541U (Panel LC370DXE (SF)(R1)).
The appearance of the power supply
Main features of the device LG 42LN540V:
Installed matrix (LED-panel) LC420DUE (SF) (R1) or LC420DUE (SF) (R3).
The matrix control uses the Timing Controller (T-CON) LC5000UE-SFR1.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the MAP3202 PWM controller. As the power elements of the LED driver, keys of the type FDT86106, STF10NM60N are used.
The necessary supply voltages for all nodes of the LG 42LN540V TV are generated by the EAX64905301 power module or its analogs using SSC1S311A (PWM flyback), NR891D (PWM Step-down 24/12) microcircuits and MDF11N65B type power switches.
MainBoard - the main board (motherboard) is an EAX64891306 module, using CPU chips: LGE-2121-MS, Spi Flash: MX25L8005 and others.
The TDSQ-G601D tuner provides television reception and channel tuning.
Information from an alternative source:
LG 42LN540V-ZA Chassis LD36B
Panel Type (Matrix): T420HVN05.2,
Motherboard: NC4.0 LD31B / LC36B / LL36B EAX64891306 (1.1),
CPU: LGE2121-MS, NAND Flash: SAA36254754, Tuner: TDSQ-G601D,
T-con: FT-5542 T28C19-3CE-0000NFP-01783-01, AUO-12309,
PSU: EAX64905301 (2.3), MAP3202, PF610BL, IC202 - NR891D, CK353A, SC1S311
Remote control: AKB73715603 part1, part2
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUE-SFR1
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 (3H)
Brightness: 300 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6/9 (Tr / Td)
Frequency: 60Hz
Lamp Type: 2 strings WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V