Technical description and composition of LG 42LF650V TV, type of panel and modules used. Module composition.
Composition
Specifications
LG 42LF650V
Smart TV 3D 42LF650V | Year of manufacture: 2015
Screen diagonal: 42" (107 cm)
Screen format: 16:9
Resolution: 1920x1080
refresh rate: 100 Hz
LCD panel type: LC420DUH-MGP1
LED backlight: Yes, Direct LED
Smart: Yes. Wi-Fi support: yes
Operating system: webOS
3D support: yes, polarizing technology, 2D to 3D conversion
Supports HD: 1080p Full HD
Progressive scan: yes
TV standards: PAL, SECAM, NTSC
Digital tuner: DVB-T, DVB-T2, DVB-C, DVB-S2
Teletext: there is
DTV formats: 480i, 480p, 576i, 576p, 720p, 1080i, 1080p
Multimedia: MP3, WMA, MPEG4, HEVC (H.265), DivX, MKV, JPEG
Stereo sound: there is
Sound power: 20W (2x10W)
Acoustics: two speakers
Interface: AV, component, HDMI x3, USB x3, Ethernet (RJ-45), Bluetooth, Wi-Fi, WiDi, Miracast
Headphone jack: yes
LG LED
Model: 42LF650V
Chassis/Version: LD/LE51H
Panel: LC420DUH (MG)(P1)
LED driver (backlight): integrated into MainBoard
PWM LED driver: LC5901
MOSFET LED driver: TO-252
Power Supply (PSU): EAX66203001 (1.6) LGP3942D-15CH1
PWM Power: PFC, PWM
MainBoard: EAX66207203 (1.0)
IC MainBoard: AT24C256, H26M31001HPR (e-NAND), K4B4G1646D-BCK0, K4B2G1646Q-BCK0, TPS65175B, NTP7515D
Tube: TDJM-G301D
General recommendations for LCD LED TV repair
Possible trouble spots
- LG 42LF650V TV does not turn on at all. Control lights are not glowing or blinking. TV does not respond to remote control and control panel buttons.
Usually with such manifestations the defect is caused by the defective elements in the main power supply module EAX66203001. It is necessary to measure its output voltages and in case of their absence check the power switches and rectifier diodes for possible short circuits in the converters.
With any breakdown of semiconductors in the secondary circuits, the inverter can usually operate normally in the emergency short-circuit mode. In this case there are no output voltages. And when a short circuit occurs in the power elements of the primary circuit, as a rule, the mains fuse and rarely the current sensor at the source of the switch break down.
Mos-Fet power switches, used in switching power supplies, sometimes fail because of failure of any other elements, which can take it out of the key mode, or cause exceeding the maximum allowable parameters of the switch. These can be the elements that feed the PWM controller, the frequency or damping circuits, or the negative feedback elements in the stabilization circuit. PFC, PWM controllers, if there is no visible damage or outright short circuits between pins, are checked by replacing with new or known good ones.
If the LG 42LF650V has no picture but has sound, often the display backlight of the LC420DUH (MG)(P1) simply does not work. Moreover, in LED-TVs usually fail LEDs inside the panel, less often the LED-driver.
In such cases you can see faintly visible image when external light hits the screen.
To replace the LEDs requires disassembly of the LCD-panel LC420DUH - the process requiring a master of experience and expertise. Do not perform such work by yourself to owners of TV sets and craftsmen who do not have experience in repairing LCD-panels.
READ HOW TO REPAIR THE TV LED BACKLIGHT --------------> HERE.
If there is no image, but backlighting works - the screen becomes slightly lighter when the TV is turned on, and in the open TV you can see the light through the holes in the body of the panel.
In this case the panel may be defective - damage to the strips, cables, for example, as a consequence of moisture after an unsuccessful washing of the screen, the T-CON board (Timing Controller) may be defective. But quite often the MainBoard EAX66207203 is defective, and software failure is also possible.
Then first it is necessary to check the panel power supply voltage, fuses on the T-CON board, as well as the supply and reference voltages of the column and line drivers - VGH, VGL, Vcom.
If these measurements are within normal limits, it is necessary to trace LVDS signals from MainBoard EAX66207203, as well as synchronizing signals to driver stubs with oscilloscope.
Filled or unsuccessfully washed LED TV screens can be restored in about half of the cases, usually, if there is no significant damage in the panel stubs and slats.
- No picture, sound is present, and the remote control responds. Or the image may appear for a second and then disappear at once.
As a rule, in such cases there is no display backlight. The reason for this may be a breakage in the circuit of the LEDs, or a problem in stabilizing their power supply.
To find the breakage in the lines of LEDs without disassembling the panel you will need a power source. It is impossible to open the transitions connected in series by simple multimeter, you need a voltage of several tens of volts.
- Indicator is blinking or glowing constantly, TV set doesn't turn on, remote control doesn't respond.
Repair or diagnosis of the motherboard EAX66207203 should begin with a check of the stabilizers and power converters needed to power the chips and matrix. If necessary, the software (software) should be updated or replaced. Often the MB board (SSB) has to be replaced if it has complex faults, which are hard to detect. When trying to repair it should be checked its elements - AT24C256, H26M31001HPR (e-NAND), K4B4G1646D-BCK0, K4B2G1646Q-BCK0, TPS65175B, NTP7515D and, failed chips replace with new ones. Some faults may be associated with the use of modern Main Board BGA soldering technology. Usually such defects are detected by local heating of the chip.
If the TV set works normally from external devices, but does not tune to the TV channels, the TDJM-G301D tuner may be defective. In such cases you should first check if there is any voltage supply to the corresponding pins. Also make sure that the tuner and the processor are communicating via the I2C bus. Sometimes a software malfunction can be the reason for the malfunction of the tuner.
Once again, please remind TV users not to try to repair it yourself, without the appropriate knowledge, experience, and necessary qualification!
Trust repairs to professionals with sufficient experience in the field of electronic repair.
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------>CHASSIS : LD51H 42LF65**, 42LF65*-Z* (42LF650, 42LF6500, 42LF650V, 42LF650T, 42LF652, 42LF652V-ZA, 42LF653, 42LF653V-ZC).
After repair of backlight EAX66203001, LC5901. Information from the master.
Reduce backlight current from 250 mA to 150 mA - replaced R816 3.0 Ohm resistor with 4.7 Ohm in the backlight current sensor on EAX66203001 board.
Limiting the driver current. EAX66203001 and LC5901. General information.
You can reduce the backlight current in LGP3942D-15CH1 (EAX66203001) TVs with the LC5901 straight-through step-down driver by increasing the current sensor resistance at the source of the converter switch.The standard current in the LEDs is 250 mA. The current sensor is a 3 ohm resistor R816. If you increase the rating to 4.3 Ohm, the current will decrease to 175 mA.
EAX66203001 current backlight
The second way to decrease the backlight current is to decrease the resistor on pin 8 of the REF LC5901 to ground.
A PDF of the ------------------> LC5901 is included.
Ways to limit the current in LED backlight drivers:
There
is a lot of information on the Internet about ways to limit the current
in the LED backlighting for different TVs and LED drivers. A lot of it
is written plausibly but sometimes it is written by people far from
electronics in order to publish any popular content on hot topics to
boost web-sites ratings.
It's impossible to talk about each case
separately within one article, because even similar models may have
different panels and different boards with their own driver variants.
But there are basic principles that are clear to craftsmen with even minimal knowledge and skill.
Other popular, complex and controversial current limit cases will be published as information becomes available.
There are three basic ways to reduce the backlight current.
1. By increasing the resistance of the LED current sensor - a low-resistance measuring resistor in the cathode (LED-) circuit.
2. Increasing the ratings of the resistors on the ISET (current setting) input of the LED driver chip.
3. changing the resistor ratings in the divider on the ADIM (Dimming) control input.
The fundamental difference between input ISET and ADIM is that ISET - input inverted, as FB, and ADIM - direct.
More on MainBoard Repair
The MainBoard EAX66207203 is shown in the figure below:
EAX66207203
The EAX66207203 can be used in televisions:
LG 50LF653V (Panel LC500DUH (MG)(P1)), LG 40LF630V 40LF630V-ZA.BRUJLDU (Panel V400HJ6-PE2 HC400DUN-VCKN1-214X), LG 40LF634V (Panel V400HJ6-PE2 Rev.C1 HC400DUN-VCKN1-214X).
The appearance of the power supply
The main features of the LG 42LF650V device:
The matrix (LED panel) LC420DUH (MG)(P1) is installed.
To power the LED backlight is used converter, combined with the main board EAX66207203, controlled by the PWM controller LC5901. As the power elements of LED-driver are used switches type TO-252.
Necessary supply voltages for all LG 42LF650V TV nodes are formed by the power module EAX66203001, or its analogues with the use of PFC, PWM chips.
MainBoard - the main board (motherboard) is EAX66207203 module, using AT24C256, H26M31001HPR (e-NAND), K4B4G1646D-BCK0, K4B2G1646Q-BCK0, TPS65175B, NTP7515D and other chips.
The TDJM-G301D tuner provides TV program reception and channel tuning.
More technical information about this panel:
Brand : LG Display
Model : LC420DUH-MGP1
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 (2H)
Brightness : 300 cd/m²
Contrast Ratio : 1200:1
Display Colors : 16.7M (8-bit), CIE1931 68%
Response Time : 6/8 (Tr/Td)
Frequency : 120Hz
Lamp Type : WLED Without Driver
Signal Interface : EPI, 100 pins
Voltage : 12.0V
Instructions and updates
There are downloadable files for the 42LF650V from the manufacturer:
Update and instruction files:
File Description File Name Type Date Size
SW File (Version 04.06.40) . TV_Software_Update_Guide_v3.pdf PDF 29.05.2020 2014K update instructions
SW File (Version 04.06.40) . Firmware (USB) Software_File(Version_04.06.40).zip zip 29.05.2020 683861K
Compatible with 32LF6309-ZA, 32LF630V-ZA, 32LF6319-ZB, 32LF631V-ZB, 32LF6329-ZC, 32LF632V-ZC, 32LF6509-ZB, 32LF650V-ZA, 32LF650V-ZB, 32LF652V-ZB, 32LF653V-ZC, 40LF6309-ZA, 40LF630V-ZA, 40LF6319-ZB, 40LF631V-ZB, 40LF6329-ZC, 40LF632V-ZC, 40LF634V-ZC, 42LF650V-ZA, 42LF650V-ZB, 42LF6529-ZA, 42LF652V-ZA, 42LF652V-ZB, 42LF653V-ZC, 43LF6309-ZA, 43LF630V-ZA, 43LF6319-ZB, 43LF631V-ZB, 43LF6329-ZC, 43LF632V-ZC, 43LF634V-ZC, 49LF6309-ZA, 49LF630V-ZA, 49LF6319-ZB, 49LF631V-ZB, 49LF6329-ZC, 49LF632V-ZC, 49LF634V-ZC, 49LF640V-ZD, 50LF650V-ZA, 50LF650V-ZB, 50LF6529-ZA, 50LF652V-ZA, 50LF653V-ZC, 55EG9109-ZB, 55EG910V-ZB, 55EG9A7V-ZB, 55LF6309-ZA, 55LF630V-ZA, 55LF6319-ZB, 55LF631V-ZB, 55LF6329-ZC, 55LF632V-ZC, 55LF640V-ZD, 55LF650V-ZA, 55LF650V-ZB, 55LF6529-ZA, 55LF652V-ZA, 55LF653V-ZC.
Manuals and User Manuals:
Document Language Date Size
Quick Start Guide English - English,Estonian,Latvian,Lettish,Lithuanian,Russian 05.19.2016 30911K
Quick Start Guide English - English,Estonian,Latvian,Lettish,Lithuanian,Russian 05.19.2016 No data
User manuals English 09/10/2015 3 270K
You can download the files for the 42LF650V model from the manufacturer's website.
LG 42LF650V 42" (107cm) diagonal 16:9 TV with LC420DUH (MG) (P1) LCD screen. In the LCD-panel the principle of direct display backlighting with a rear arrangement of LEDs - Direct LED is implemented.
There is support of 3D image using passive polarization technology.
The LC420DUH matrix and MainBoard software EAX66207203 provide for viewing shows and movies in high quality HD at 1920x1080 pixels in 1080p (Full HD) resolution.
The 42LF650V has built-in SMART software and webOS operating system. Connection to the network can be made via wireless Wi-Fi connection. Input analog video signal is decoded in PAL, SECAM, NTSC systems. Graphic processing of a digital signal is done in 480i, 480p, 576p, 720p, 1080i, 1080p. Supported media file formats: MP3, WMA, MPEG4, HEVC (H.265), DivX, MKV, JPEG.
The sound system capacity of 20 W (2x10 W) is provided by two speakers. NICAM stereo sound processing system and Sound Surround surround function are used.
Communication with other devices via an external interface is supported by standard input and output connectors: Antenna input (RF), AV, component, HDMI x3, USB x3, Ethernet (RJ-45), Bluetooth, Wi-Fi, WiDi, Miracast. There is a headphone jack. There is a VGA (D-Sub 15) connector to connect a computer or laptop to this TV model. This interface supports standard resolutions: 640x480, 800x600, 1024x768, 1280x1024, 1360x768, 1920x1080. The digital tuner is able to receive TV channels in the standards DVB-T, DVB-T2, DVB-C, DVB-S2.
The TV uses EAX66203001 power supply.
Warning. Panel LC420DUH LED-TV LG 42LF650V is an expensive and unreliable element of it.
Do not allow any impact on the glass and pressure on the surface of the screen to avoid damage to the LED-panel!
Also it is not safe to get liquid on the screen. Sometimes one drop is enough if it drips down the glass onto the cables and the TV becomes unrepairable.
