Technical description and composition of the LG 42LY345C TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LY345C
Chassis / Version: LD4CA
Panel: LC420DUE (FG) (A3)
LED backlight: 6916L-1956A / 1957A - LG lnnotek DRT 3.0 42_A / B type Rev01
T-CON: 6870C-0480A V14 42 DRD 60Hz Control_Ver 0.3
LED driver (backlight): integrated into PSU
PWM LED driver: BD9486F, NR134S
MOSFET LED driver: 4NF20, MDD3752
Power Supply (PSU): EAX65423701 (2.0) REV2.0 - LGP3942-14PL1
PWM Power: MAP8800, FA6A01N, NR134S
MOSFET Power: TK7P60W
MainBoard: EAX65486303 (1.0)
IC MainBoard: 24C256, MX25L8006E, MX25L8005
Tuner: TDJH-G101D
Specifications 42LY345C
LG 42LY345C
General repair guidelines for TV LCD LED
Possible manifestations of defects
- LG 42LY345C does not turn on and does not show any signs of performance at all. Does not blink indicators and does not respond to control buttons.
In some of these cases, a malfunction is detected in the EAX65423701 power module. It is necessary to measure its output supply voltages, and in case of their absence, check the serviceability of the power switches of the converters and rectifier diodes for the probability of breakdown in PN semiconductor junctions.
In case of breakdowns of diodes in the secondary circuits, the converter can operate in emergency short circuit mode without output voltages, and during short circuit in the power elements of the primary circuit, the mains fuse and / or current sensor at the source of the key usually breaks.
Mos-Fet power switches, used in switching power supplies, sometimes fail due to a malfunction of any other elements that can put it out of operation in key mode, or create an excess of the maximum permissible parameters of the switch. These can be elements supplying the PWM controller, frequency-setting or damping circuits, or negative feedback elements in the stabilization circuit. PWM controllers, in the absence of visible damage or explicit short-circuit between the terminals, are checked by replacing with new ones, or obviously working.
- There is no image, but there is sound, it reacts to the remote control. Or the image appears when you turn it on and immediately disappears
A malfunction is usually most likely in these cases at the backlight nodes of the display matrix. The reason can be both in the power of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
It is impossible to detect a break in the LED line without disassembling the panel with a simple multimeter. The LEDs are connected in series and to open their transitions, a voltage of several tens of volts is required. Ideally, a current source is suitable for such purposes. You can open the panel and check each LED separately. Typically, Chinese multimeters light up a single 3-volt LED, if you connect the probes in the forward direction to it (red probe to the anode, black to the cathode). In dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of health. In the event of a LED malfunction, its zener diode will either be cut off or broken into short-circuit.
- The TV does not enter the operating mode, does not respond to the remote control. The indicator on the front panel lights constantly or blinks.
Repair or diagnostics of the EAX65486303 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). In cases of attempts to repair the MB (SSB) board, it is necessary to check the serviceability of its elements - 24C256, MX25L8006E, MX25L8005 which may require replacement with new ones. If a BGA processor is installed, there is a possibility of a violation of the soldering of the contacts of its conclusions with the board (it is diagnosed by heating).
Before replacing the TDJH-G101D tuner, if there is no tuning for 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
It should be remembered! Attempts to self-repair the LG 42LY345C TV, in the absence of the necessary qualifications and experience, are categorically not recommended and are fraught with negative consequences, up to the complete non-repairability of the device!
Backlight Current Limit:
In televisions with power supplies LGP3942-14PL1 (EAX65423701), the backlight current sensor - the resistor block R811-R818 consists of four pairs of 4.3 Ohm each. You can reduce the backlight current by 25% by removing one pair of resistors.
The appearance of the MainBoard EAX65486303 is shown in the figure below:EAX65486303
The appearance of the power supply
Main features of the device LG 42LY345C:
Installed matrix (LED-panel) LC420DUE (FG) (A3).
The matrix control uses the Timing Controller (T-CON) 6870C-0480A.
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by the BD9486F, NR134S PWM controller. As power elements of the LED driver, keys of the type 4NF20, MDD3752 are used.
The necessary supply voltages for all nodes of the LG 42LY345C TV are generated by the EAX65423701 power supply module or its analogs using MAP8800, FA6A01N, NR134S microchips and TK7P60W power switches.
MainBoard - the main board (motherboard) is an EAX65486303 module, using 24C256, MX25L8006E, MX25L8005 chips, and others.
The TDJH-G101D tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUE-FGA3
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 (G to G)
Frequency: 60Hz
Lamp Type: WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V