Thursday, 27 February 2020

REPAIR / SERVICING TV LG 42LM585S

Technical description and composition of the LG 42LM585S TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LM585S -ZD
Chassis / Version: LD21B
Panel: LC420EUE (SE) (F1)
LED backlight: 6922L-0016A (Cool); 6920L-0001C (LED)
T-CON: 6870C-0401B; TPS65198
LED driver (backlight): integrated into PSU 67V 0.78A
PWM LED driver: R5F100BCAFP, AAT2430AISX
MOSFET LED driver: PHT4NQ10LT
Power Supply (PSU): EAX64427101 LGP4247L-12LPB
PWM Power: FAN7930BG (PFC), L6599AD, STR-A6059 (Stb)
MOSFET Power: STF13NM60N, STF10NM60N, FDT86106LZ
MainBoard: EAX64317403
IC MainBoard: CPU: LGE2111A-T8, Nand: NAND01GW3B2CN6E, DDR: H5TQ1G63DFR-H9C, SPI Flash: W25Q80BV
Tuner: TDSQ-G001D
Specifications 42LM585S
LG 42LM585S
General repair guidelines for TV LCD LED
Possible malfunctions
- LG 42LM585S does not turn on, the indicators on the front panel do not light or flash. The TV does not respond to the control buttons and the remote control.
With such manifestations, in some cases, the EAX64427101 power module is faulty. It is then necessary to measure its output voltages and, if they are absent, you should check the power switches (STF13NM60N, STF10NM60N, FDT86106LZ) and rectifier diodes of the converters for a short circuit probability.
In case of breakdowns of semiconductors in the secondary circuits, the converter can usually work abnormally in the short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse often breaks.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements that can put it out of operation in key mode or provoke an excess of the maximum current or voltage. These can be circuits supplying the PWM controller, damping or frequency-setting circuits, or elements of OOS (negative feedback) in the stabilization circuit. PWM controllers (PWM) FAN7930BG (PFC), L6599AD, STR-A6059 (Stb), in the absence of external damage and short circuit between the terminals, are checked by replacing with obviously good ones.
- 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 such cases, the most likely malfunction of the LED backlight elements. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To check the health in the LED circuit, it is better to use a current source with a maximum voltage of 200V. We do not recommend using any voltage sources for this purpose. You can check each LED individually with a simple Chinese multimeter (powered by 9 volts) in the P-N-junction test mode. If you connect the red probe of the multimeter to the anode of the LED, and the black to its cathode, then the 3-volt LED will light up slightly, and in the opposite direction you can detect the transition of the emergency zener diode. A zener diode PN junction indirectly indicates a LED-a
- The TV does not turn on, the indicator indicates standby or operating mode, or blinks.
Repair or diagnostics of the EAX64317403 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). 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: LGE2111A-T8, Nand: NAND01GW3B2CN6E, DDR: H5TQ1G63DFR-H9C, SPI Flash: W25Q80BV. BGA chip malfunctions are usually easy to detect by warming up.
Before replacing the TDSQ-G001D tuner, if there is no tuning to the channels, you must first check the software and the supply voltage at its terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus
Once again, we remind TV users: you should not make attempts to repair it yourself without the appropriate knowledge, experience and the necessary qualifications! Entrust repair to professionals with sufficient experience in the field of repair of electronic equipment.


SCHEMATIC DIAGRAM --------->  LG 42LM585S Chassis LD21B. YEAR  2012  MODS: 42LM580S, 42LM580T, 42LM585S -ZA/ZD


 To reduce the backlight current in LED drivers with the AAT2430AISX controller, increase the resistance of the resistor from terminal 50 (ISET) to the housing, for example, from 3 KOhm to 4.7 KOhm. Currents will proportionally decrease in each of the 16 channels. With a parallel connection of channels, currents are summed.


 The appearance of the MainBoard EAX64317403 is shown in the figure below:
EAX64317403
EAX64317403 can be used in TVs:
LG 32LM580S (Panel LC320EUN (SE)(F2)), LG 32LS5610 (Panel T320HVN01.0), LG 42LM580S ZA (Panel LC420EUE (SE)(F1)), LG 42LS5620 (Panel T420HVN01.1), LG 32LS5600 (Panel T320HVN01.0), LG 42LM585S -ZD (Panel LC420EUE (SE)(F1)).
The appearance of the power supply
Main features of the device LG 42LM585S:
Installed matrix (LED-panel) LC420EUE (SE) (F1).
The matrix control uses the Timing Controller (T-CON) 6870C-0401B ;.
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by a PWM controller R5F100BCAFP, AAT2430AISX. As power elements of the LED driver, keys of the PHT4NQ10LT type are used.
The necessary supply voltages for all nodes of the LG 42LM585S TV are generated by the EAX64427101 power module or its analogs using FAN7930BG (PFC), L6599AD, STR-A6059 (Stb) microchips and power switches of the STF13NM60N, STF10NM60N, FDT86106LZ type.
MainBoard - the main board (motherboard) is an EAX64317403 module using CPU chips: LGE2111A-T8, Nand: NAND01GW3B2CN6E, DDR: H5TQ1G63DFR-H9C, SPI Flash: W25Q80BV and others.
The TDSQ-G001D tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUE-SEF1
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 (3H)
Brightness: 360 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6 (G to G)
Frequency: 60Hz
Lamp Type: 6 strings WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V