Technical description and composition of the THOMSON T42E04DHU TV, panel type and modules used. The composition of the modules.THOMSON LED
Model: T42E04DHU
Chassis / Version: MPLE31N75
Panel: LVF420AUDX E16 V8
LED backlight: 017-420-0006-1 42RT7020S56A0 V1
T-CON: T420HVN06.1 CTRL BD 42T34-C01
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP3398A
MOSFET LED driver: SM2A04NSU
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MainBoard: MPLE31N75 REV1.2 DLH8000753
IC MainBoard: ST34WN-2T-E CPU: MT5531, SPI FLASH: 25Q64, AUDIO: RT9108NB
Tuner: ST34WN-2T-E
Specifications T42E04DHU
THOMSON T42E04DHU
General recommendations for TV LCD LED repair
Possible manifestations of defects
- The THOMSON T42E04DHU TV does not turn on, does not respond to the remote control and control panel buttons, the indicators do not light up or flash.
In this case, first of all, you should check the operability of the main power source - the AC / DC voltage converter, all the elements of which are located on the MainBoard MPLE31N75. Its output voltages should be measured and, in their absence, the serviceability of the power switches and rectifier diodes in the converters should be checked for possible breakdown.
In case of breakdowns in the secondary circuits, the converter can operate in short-circuit mode, and in case of short-circuit in the elements of the primary circuit, the mains fuse usually breaks off.
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 regulators (PWM) PWM SOT23-6, if they do not have visible damage to the case and an open short circuit between the pins, are usually checked by replacing.
- There is no picture, but there is sound and reaction to commands from the remote control. Or the image appears immediately after switching on and disappears.
A malfunction is usually in these cases most likely in the backlight units of the display matrix. Often the reason is a malfunction of the LEDs (open circuit, short circuit ...), or the connectors of the strips (strings), less often the LED driver turns out to be faulty.
To test the LED strips, in order to open all the transitions of the LEDs, several tens of volts or more are needed; it is best to use a current source for such purposes. The breakage of several PN junctions connected in series cannot be detected with a multimeter or tester. In such cases, it is necessary to open the panel and check each LED. If your multimeter cannot open the LED junctions in forward bias, you can sometimes detect the presence of a protective zener diode PN junction by connecting the probes in the opposite direction. If the zener diode is cut off or broken in K / Z, then the LED is faulty and needs to be replaced.
- The TV does not turn on, the indicator signals the standby or operating mode, or blinks.
Repair or diagnostics of the MPLE31N75 motherboard should begin with checking the stabilizers and power converters required to power the microcircuits and matrix. If necessary, you should update or replace the software (software). Sometimes it is necessary to check or replace (if necessary) elements of the MainBoard - ST34WN-2T-E CPU: MT5531, SPI FLASH: 25Q64, AUDIO: RT9108NB. In cases where a BGA processor is used, its malfunction is usually detected by the local warm-up method.
If there is no tuning for terrestrial or cable TV channels, you should make sure that the software is correct, as well as that the supply voltages on the ST34WN-2T-E tuner terminals are in line. It is also necessary to check with an oscilloscope the presence of pulses of data exchange between the tuner and the processor via the I2C bus.
If THOMSON T42E04DHU has no picture, but there is sound, often the 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 LCD panel - a process that requires experience and qualifications from the master. 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, light can be seen through the holes in the panel case.
In this case, the panel may also be faulty - damage to the 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 often the main board MainBoard 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 the MainBoard with an oscilloscope, as well as synchronizing 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.
Once again, we remind TV users: you should not try to repair yourself without the appropriate knowledge, experience and the necessary qualifications! Trust the repairs to professionals with sufficient experience in the field of electronic repair.
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> THOMSON Chassis MPLE31N75-2B-T
DOWNLOAD FIRMWARE FOR SPI FLASH -----------> THOMSON T42E04DHU, Main: MPLE31N75 REV1.2 DLH8000753, Panel: LVF420AUDX E16 V8
The appearance of the MainBoard MPLE31N75 is shown in the figure below:MPLE31N75
The main features of the THOMSON T42E04DHU device:
Installed matrix (LED panel) LVF420AUDX E16 V8.
Matrix control uses the T420HVN06.1 Timing Controller (T-CON).
To power the backlight LEDs, a converter combined with the MPLE31N75 main board is used, controlled by the MP3398A PWM controller. The keys of the SM2A04NSU type are used as power elements of the LED driver.
The power module is combined with the MainBoard and is made according to the AC / DC flyback voltage converter using PWM SOT23-6 microcircuits.
MainBoard - the main board (motherboard) is an MPLE31N75 module using ST34WN-2T-E CPU: MT5531, SPI FLASH: 25Q64, AUDIO: RT9108NB and others.
The ST34WN-2T-E tuner provides reception of television programs and tuning to channels.
LED TV THOMSON T42E04DHU with LCD display, diagonal 42 "(107 cm) in 16: 9 format. The design of the LCD panel uses edge LED backlighting - Edge LED. The design and technical capabilities of the TV provide viewing in high quality HD at a resolution of 1920 x 1080 pixels in graphic format according to the standard 1080p (Full HD) .Input high-frequency or video signal is decoded in analog systems PAL, SECAM, NTSC. Digital signal formation (graphic format) is performed in the standards 480i, 480p, 576i, 576p, 720p, 1080i , 1080p Supported media formats: MP3, JPEG.
Speaker power 6 W (2x3 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, component, SCART, VGA, HDMI x3, USB. A standard VGA (D-Sub 15) connector is used to connect a laptop or computer. This interface supports resolutions: 640x480, 800x600, 1024x768, 1280x1024, 1360x768, 1920x1080. The digital tuner has the ability to receive television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Attention! The panel of the THOMSON T42E04DHU LED TV is an expensive and unreliable element.
Do not allow any impact on the glass and pressure on the screen surface to avoid damage to the LED panel!
It is also unsafe for liquid to spill onto the screen. Sometimes one drop is enough if it drips down the glass onto the cables to make the TV unrepairable.