Technical description and composition of the PANASONIC TX-L42D25 TV, panel type and modules used. The composition of the modules.PANASONIC LED
Model: TX-L42D25 TX-LR42D25
Chassis / Version: LA02
Panel: LC420EUH
LED backlight: EDGE LED
LED driver (backlight): integrated into PSU
Power Supply (PSU): PS-311 N0AE4JJ00006
MainBoard: TNPH0851 A2 & T-BOARD
IC MainBoard: CPU: MN2WS0110C, MN103SH9F (Stb), H27U1G8F2BTR, LV4921
Tuner: ENGF7801KF
TX-L42D25 Specifications
PANASONIC TX-L42D25
General recommendations for TV LCD LED repair
Possible manifestations of malfunctions
- The PANASONIC TX-L42D25 TV does not turn on and does not show any signs of operability at all. No response to the remote control and front panel control buttons.
With such manifestations, a malfunction is most likely found in the PS-311 power supply module. Then you should measure its output voltages and, in case of their complete or partial absence, it is necessary to check the serviceability of the power switches and rectifier diodes of the converters for the presence of a possible short circuit.
In case of breakdowns of semiconductors in the secondary circuits of any converter, as a rule, it can operate in an emergency mode of short circuit without output voltages, and with a short circuit in the elements of the primary circuit, the mains fuse most often breaks off immediately and less often the current sensor in the source of the key.
Breakdown of power switches (MosFet) in switching sources is sometimes caused by malfunctions of other circuit elements, for example, in the circuits supplying the PWM controller, frequency setting or damper, as well as in the circuits of Negative Feedback (OOS) stabilization. PWM controllers (PWM), if they do not have visible damage to the case and an outright short circuit between the terminals, are usually checked by replacement.
- There is no picture, but there is sound, it reacts to the remote control. Or the image appears when turned on and disappears immediately
The malfunction in most of such cases is found in the nodes and elements of the LED panel backlight. The reason for this may be an open circuit in the LED circuit, or a problem in stabilizing their power supply.
Without a special current source, it is impossible to check the line of series-connected LEDs, and it is unsafe for them to use any voltage sources over 12V for this purpose. Then all that remains is to open the panel and check each LED separately. Usually, Chinese multimeters with 9V power supply lightly light up one 3-volt LED, if you connect the probes to it in the forward direction, the red probe to the anode, the black one to the cathode. For dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of the LED health. In the event of a malfunction of the LED, its zener diode will either be cut off or pierced in the K / Z.
- The indicator blinks or is on constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the TNPH0851 motherboard should begin with checking the stabilizers and power converters necessary to power the microcircuits and the matrix. If necessary, you should update or replace the software (software). In some cases, to repair the MB (SSB) board, it may be necessary to replace the chips - CPU: MN2WS0110C with new or known good ones. In cases where BGA technologies are used, defects are usually localized by heating.
If the PANASONIC TX-L42D25 has no picture, but there is sound, often the LC420EUH display backlight simply does not work. Moreover, in LED TVs, the LEDs inside the panel usually fail, less often the LED driver.
In such cases, you can see a barely noticeable image with a successful hit of external light on the screen.
Replacing the LEDs requires disassembling the LC420EUH LCD panel - a process that requires experience and qualifications from the technician. We do not recommend doing such work on your own to the owners of TVs and craftsmen who do not have experience in repairing LCD panels
If there is no image, and the backlight is on, the screen becomes slightly lighter when turned on, and in an open TV you can see light through the holes in the panel case.
In this case, the panel may also be faulty - damage to strips, loops, for example, as a result of moisture ingress after unsuccessful washing of the screen, the T-CON (Timing Controller) board may be faulty. But the main board MainBoard TNPH0851 often turns out to be faulty, a software failure is also possible.
Then, first of all, you need to check the panel supply voltage, the 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 the passage of LVDS signals from MainBoard TNPH0851 with an oscilloscope, as well as synchronization signals to the loops with drivers.
Flooded or unsuccessfully washed screens of LED TVs can be restored, in about half of the cases, usually if significant damage has not formed in the loops and panel strips.
Attention to users! Self-repair of the PANASONIC TX-L42D25 TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> PANASONIC TX-L42D25 Chassis LA02 TX-L42D25B, TX-L42D26B
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> PS-311 N0AE4JJ00006 Power supply
The appearance of the MainBoard TNPH0851 is shown in the figure below:TNPH0851
The main features of the PANASONIC TX-L42D25 device:
Installed matrix (LED panel) LC420EUH.
A converter combined with a power supply is used to power the backlight LEDs.
The formation of the necessary supply voltages for all nodes of the PANASONIC TX-L42D25 TV is carried out by the PS-311 power supply module, or its analogs.
MainBoard - the main board (motherboard) is a TNPH0851 module, using CPU microcircuits: MN2WS0110C, MN103SH9F (Stb), H27U1G8F2BTR, LV4921 and others.
The ENGF7801KF tuner provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUH-LFF1
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: 400 cd / m²
Contrast Ratio: 1500: 1
Display Colors: 16.7M (8-bit), CIE1931 72%
Response Time: 8/10 (Tr / Td)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V
PANASONIC TX-L42D25 TV with LCD LC420EUH, 42 "(107 cm) 16: 9 diagonal. Dynamic contrast ratio of 2,000,000: 1 is achieved by special control of the LEDs. The LED panel of this TV has an edge LED backlight - Edge LED ...
The LC420EUH panel and TNPH0851 motherboard firmware provide HD and Full HD viewing at 1920x1080 pixels in 1080p (Full HD) graphics.
The TX-L42D25 TV is equipped with SMART software, built-in applications and the ability to work on the Internet. Internet connection can be made via Wi-Fi wireless connection. The input analog video signal can be processed in PAL, SECAM, NTSC systems. Graphic processing and formation of a digital signal picture occurs in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Multimedia file formats supported by the video processor: MP3, DivX, JPEG.
The power of the acoustic audio system is 20 W (2x10 W) provided by two speakers. Uses NICAM stereo signal system and Sound Surround function.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV x3, audio x3, component, VGA, HDMI x3, USB x2, Ethernet (RJ-45), Wi-Fi. A headphone output is provided for individual listening. To connect a computer or laptop, a VGA (D-Sub 15) connector is used that supports resolutions: 640x480, 800x600, 1024x768, 1280x1024, 1360x768.
The digital tuner is capable of receiving terrestrial and cable channels in DVB-T MPEG4 standards.
The power consumed by the TV in operating mode from the mains is 152 W.
Dimensions: with stand 1032x697x329 mm, without stand 1032x655x77 mm.
TV weight: with stand: 21.5 kg, without stand: 18.5 kg.
Attention! The LC420EUH panel of the PANASONIC TX-L42D25 LED TV is the most expensive item.
Do not allow any impact on the glass and pressure on the screen surface to avoid damage to the LED panel!
Liquid spillage on the screen is unsafe. Sometimes one drop is enough if it drips down the glass onto the cables to make the TV unrepairable.
