Friday, 28 February 2020

REPAIR / SERVICING TV LG 42LS561T

Technical description and composition of the LG 42LS561T TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LS561T
Chassis / Version: LD21B
Panel: T420HVN01.1
LED backlight: Edge LED 42 inch 7030PKG 64EA
T-CON: T315HW07 VB 31T14-COJ
LED driver (backlight): integrated into PSU
PWM LED driver: DF3421
MOSFET LED driver: PA610AD
Power Supply (PSU): EAX64427001 LGP42L-12P EAY62608801
PWM Power: FAN7930BMX (PFC), ICE3BR4765JZ (Stb), L6599AD
MOSFET Power: STD10NM60N (PFC), STD7NM60N
MainBoard: EAX64317404 (1.0)
IC MainBoard: LGE2111A-T8, H27U1G8F2BTR, W25Q80B, AT24C256C, STA3808WE
Tuner: TDSS-G101D
Control: IR: EBR74986702 LM35-55 Ver2.2
Specifications 42LS561T
LG 42LS561T
General repair guidelines for TV LCD LED
Possible malfunctions
- The LG 42LS561T TV does not turn on, does not respond to the remote control and the control panel buttons, does not light up or blink indicators.
Usually, with such manifestations, the defect is caused by faulty elements in the main power supply module EAX64427001. It is necessary to measure its output voltages, and in case of their absence, check the operability of power switches (STD10NM60N (PFC), STD7NM60N) of converters and rectifier diodes for a short circuit probability.
In case of any breakdowns in the secondary circuits, the converter can operate in emergency short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse or the current sensor at the source of the key more often breaks.
The breakdown of Mos-Fet keys used in pulsed sources is often caused by malfunctions of other elements, for example, in the power supply circuit of a PWM controller, in frequency-setting or damping circuits, as well as in Negative Stabilization Feedback. PWM chips FAN7930BMX (PFC), ICE3BR4765JZ (Stb), L6599AD are usually checked by replacing with new ones, or obviously working.
- There is no image, but there is sound and reaction to the remote control. Or for a second, the image may appear immediately after switching on.
Often in such cases, there is no LED backlight. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
When trying to detect a break in the LED lines, it should be taken into account that it is difficult to do this without disassembling the panel. For example, a current source is needed to open PN junctions connected in series.
- 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 EAX64317404 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). Sometimes it is necessary to check or replace (if necessary) the elements of the MainBoard board - LGE2111A-T8, H27U1G8F2BTR, W25Q80B, AT24C256C, STA3808WE. In cases where the BGA processor is used, its malfunction is usually detected by the local heating method.
If a TDSS-G101D tuner is suspected of malfunction, first of all, it is necessary to verify the correctness of the software, as well as the presence of the required voltage levels and data exchange pulses with the processor via the I2C bus at the corresponding tuner pins.
We recommend the owners of the 42LS561T TV for repair only to qualified specialists with the necessary work experience! Self-repair attempts without the appropriate knowledge and skills can lead to irreversible negative consequences!



 SCHEMATIC DIAGRAM ---------->  LG 42LS561T Chassis LD21B


 The appearance of the MainBoard EAX64317404 is shown in the figure below:
EAX64317404
EAX64317404 can be used in TVs:
LG 32LS560T (Panel LC320EUN (SE)(M2)), LG 42LS5600 (Panel T420HVN01.1), LG 47LM580T (Panel LC470EUE (SE)(U1)), LG 42LM3400 (Panel LC420DUN (SE)(U2)), LG 37LS560T (Panel LC370EUN (SE)(M2)), LG 32LM340T (Panel LC320DXN (SE)(U3)), LG 47LM615S (Panel LC470EUE (SE)(U1)), LG 32LM3400 32LM3400-ZA (Panel LC320DXN (SE)(U2)).
The appearance of the power supply
Main features of the device LG 42LS561T:
The matrix (LED panel) T420HVN01.1 is installed.
The matrix control uses the Timing Controller (T-CON) T315HW07.
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by a DF3421 PWM controller. As the power elements of the LED driver, keys of the type PA610AD are used.
The necessary supply voltages for all nodes of the LG 42LS561T TV are generated by the EAX64427001 power module or its analogs using FAN7930BMX (PFC), ICE3BR4765JZ (Stb), L6599AD microcircuits and power switches of the STD10NM60N (PFC), STD7NM60N type.
MainBoard - the main board (motherboard) is an EAX64317404 module, using chips LGE2111A-T8, H27U1G8F2BTR, W25Q80B, AT24C256C, STA3808WE and others.
The TDSS-G101D tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: AUO
Model: T420HVN01.1 CELL
Type: a-Si TFT-LCD, CELL
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: AMVA3, Normally Black
Active Area: 930.24x523.26 mm
Surface: Antiglare (Haze 2%), Hard coating (3H)
Glass Depth: 0.50 + 0.50 mm
Transmissivity: 5.7% (with Polarizer)
Contrast Ratio: 3000
Display Colors: 16.7M (8-bit), CIE1931 72%
Response Time: 6.5 (G to G)
Frequency: 60Hz
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V