Friday 28 February 2020

REPAIR / SERVICING TV LG 42LM660T

Technical description and composition of the LG 42LM660T TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LM660T 42LM660T-ZA.BRUWLJU
Chassis / Version: LD22E
Panel: LC420EUG (PE) (F1)
LED backlight: 6922L-0023A, 6920L-0001C (6916L0948A, 6916L0947A)
LED driver (backlight): integrated into PSU
PWM LED driver: AAT2430AISX, R5F100BCAFP, UC2843BD1
MOSFET LED driver: PHT4NQ10LT, STF19NF20
Power Supply (PSU): EAX64744201 (1.3)
PWM Power: STR-A6059H (Stby), L6599AD, FAN7930BG (PFC)
MOSFET Power: STF10NM60N, STF13NM60N
MainBoard: EAX64307906 (1.0) EBR75226848
IC MainBoard: LCE2112, 24C16, H5TQ2G63DFR, KLM2G1HE3F, R5F100GEA, TPS65178, STA3808WE
Tuner: EBL61080002 TDSN-G351D
Control: Remote: AKB73615303, WIFI: TWFM-B003D EAT61613401
Specifications 42LM660T
LG 42LM660T
General repair guidelines for TV LCD LED
Possible manifestations of defects
- LG 42LM660T TV does not turn on at all. The control lights do not light or flash. The TV on the remote control and the control panel buttons do not respond.
In such cases, the EAX64744201 power supply is usually faulty. It is necessary to measure its output voltages and, in case of their absence, check the serviceability of power switches (STF10NM60N, STF13NM60N) and rectifier diodes in the converters for possible breakdown.
In case of breakdowns in the secondary circuits, the converter, as a rule, can emergency work in the short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse usually 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) STR-A6059H (Stby), L6599AD, FAN7930BG (PFC), 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.
Usually in such cases, a malfunction is detected in the backlight nodes of the LED panel. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To detect a break in the LED lines without disassembling the panel, a current source is required. It is impossible to open transitions connected in series with a simple multimeter; voltage of several tens of volts is necessary.
- The indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the EAX64307906 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 LCE2112, 24C16, H5TQ2G63DFR, KLM2G1HE3F, R5F100GEA, TPS65178, STA3808WE. 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.
Before changing the tuner EBL61080002 TDSN-G351D, if it is not possible to tune to television channels, make sure that there are supply voltages that need to be measured at the corresponding terminals of the tuner and check the software for correctness. The pulses of the data exchange of the tuner with the processor can be controlled by an oscilloscope
TV users and owners need to remember that attempts to self-repair an LG 42LM660T TV without the appropriate qualifications and necessary experience can lead to serious negative consequences!


 SCHEMATIC DIAGRAM ---------->  LG CHASSIS LD22E; MODEL 42LM660S, 42LM660T, 42LM669S, 42LM669T, 42LM660S/660T-ZA 42LM669S/669T-ZC


 The appearance of the MainBoard EAX64307906 is shown in the figure below:
EAX64307906
EAX64307906 can be used in TVs:
LG 32LM640T ZA (Panel LC320EUA PE F2), LG 32LS570T (Panel LC320EUN (SE)(M2)), LG 47LM620S (Panel LC470EUE (SE)(F4)), LG 42LM670T (Panel LC420EUG(PE)(F2)), LG 42LM640T 42LM640S (Panel LC420EUG (PE)(F1)), LG 42LM620T (Panel LC420EUE (SE)(F1)), LG 47LM660T (Panel LC470EUG (PE)(F1)), LG 42LS570T (Panel T420HVN01.0), LG 42LS570S ZB (Panel LC420EUE (SE)(M1)), LG 42LM669T (Panel LC420EUG (PE)(F2)), LG 42LM669S (Panel LC420EUG (PE)(F1)), LG 37LM620T (Panel LC370EUN (SE)(F2)), LG 47LM669 (Panel LC470EUG (PE)(F2)), LG 32LS570S ZB (Panel LC320EUN (SE)(M2)), LG 47LM620T (Panel LC470EUE (SE)(F3)), LG 47LM761T ZA (Panel LC470EUH (PE)(F1), LG 32LM620S (Panel LC320EUN (SE)(F2) ), LG 47LM670T 47LM670T-ZA.BRUWLJU (Panel LC470EUG (PE)(F1)), LG 42LM660S 42LM660S-ZA.BRUWLJU (Panel LC420EUG (PE)(F1)), LG 42LM660T 42LM660T-ZA.BRUWLJU (Panel LC420EUG (PE)(F1) ), LG 32LM620T (Panel LC320EUN (SE)(F3)), LG 55LM620T 55LM620T-ZE (Panel LC550EUE (SE)(F1)).
The appearance of the power supply
Main features of the device LG 42LM660T:
Installed matrix (LED-panel) LC420EUG (PE) (F1).
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by the AAT2430AISX, R5F100BCAFP, UC2843BD1 PWM controller. As the power elements of the LED driver, keys of the type PHT4NQ10LT, STF19NF20 are used.
The necessary supply voltages for all nodes of the LG 42LM660T TV are generated by the EAX64744201 power supply module or its analogs using STR-A6059H (Stby), L6599AD, FAN7930BG (PFC) microcircuits and power switches of the STF10NM60N, STF13NM60N type.
MainBoard - the main board (motherboard) is an EAX64307906 module, using LCE2112, 24C16, H5TQ2G63DFR, KLM2G1HE3F, R5F100GEA, TPS65178, STA3808WE and other chips.
The tuner EBL61080002 TDSN-G351D provides the reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUG-PEF1
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 930.24x523.26 mm
Surface: Antiglare (Haze 1%), Hard coating (2H)
Brightness: 360 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 8/10 (Tr / Td)
Frequency: 60Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V