Friday 11 September 2020

REPAIRING / SERVICING TV THOMSON T24E12DHU-01B

Technical description and composition of the THOMSON T24E12DHU-01B TV, panel type and modules used. The composition of the modules.
THOMSON LED
Model: T24E12DHU-01B T24E12DHU
Chassis / Version: MT31BP
Panel: LVW240AUDX E2 V6
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP3398A
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6 (RT7738F)
MainBoard: 40-MT31BP-MAA2LG
IC MainBoard: CPU: MT5531NDNT; SPI Flash: 25Q64F; SOUND: RT9108NB
Tuner: ST34WN-2T-E
Specifications T49D21SF-01B
THOMSON T24E12DHU-01B
General recommendations for TV LCD LED repair
Possible manifestations of malfunctions
- The THOMSON T24E12DHU-01B 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.
A malfunction in such cases should be looked for in the elements of the power source - the mains voltage converter (AC / DC), which is located on the MainBoard 40-MT31BP-MAA2LG. Its output voltages should be measured and, in their absence, the power switches and rectifier diodes should be checked for the probability of a short circuit in the converters.
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 Mos-Fet switches used in switching power supplies is often caused by malfunctions of other elements, for example, in the power supply circuit of the PWM controller, in frequency setting or damper circuits, as well as in negative feedback stabilization. PWM microcircuits (PWM) PWM SOT23-6 (RT7738F) are usually checked by replacing them with new ones, or knowingly working.
- There is no picture, but there is sound and reaction to the remote control. Or, for a second, the image may appear immediately after switching on.
Usually, in such cases, a malfunction is detected in the LED panel backlight nodes. The reason may be both in the power supply of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
When diagnosing, it must be borne in mind that it is impossible to check for an open in the circuit of the LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally a current source. By opening the panel, you can check each LED separately. Typically, Chinese multimeters will lightly light one 3-volt LED if you connect the probes to it in the forward direction. For dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of LED health. In the event of a malfunction of the LED, its zener diode will either be cut off, or broken through in the K / Z.
- The TV does not turn on, the indicator signals the standby or operating mode, or blinks.
Repair or diagnostics of the 40-MT31BP-MAA2LG 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). Often the MB (SSB) board must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU: MT5531NDNT; SPI Flash: 25Q64F; SOUND: MP3398A and replace out-of-order chips with new ones. Some malfunctions may be associated with the use of BGA soldering technologies in modern Main Board. Typically, such defects are detected by local heating of the chip.
Before changing the ST34WN-2T-E tuner, if it is not possible to tune to TV channels, you should make sure that there are supply voltages, which must be measured at the corresponding tuner terminals and check the software for correctness. The pulses of the data exchange of the tuner with the processor can be monitored with an oscilloscope

 If THOMSON T24E12DHU-01B 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 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.


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 FIRMWARE FOR SPI FLASH  ----------->   THOMSON T24E12DHU-01B T24E12DHU, Main: 40-MT31BP-MAA2LG, Panel: LVW240AUDX E2 V6

https://2.bp.blogspot.com/-ejN2xTiNSVU/XyPbplUyOzI/AAAAAAABCcY/EK-rt63MkYoAVA_q23xBYF6cB3smjAIDwCK4BGAYYCw/s1600/40-MT31BP-MAA2LG_DCE.jpg The appearance of the MainBoard 40-MT31BP-MAA2LG is shown in the figure below:
40-MT31BP-MAA2LG
40-MT31BP-MAA2LG can be used in TVs:
ERISSON 32LET82 (Panel LVW320CSOT E145 V2), ERISSON 32LET42T2 (Panel LVW320CSOT E274 V2), ERISSON 32LET41T2 (Panel LVW320CS0T E274 V2), FUSION FLTV-32T21 (Panel LVW320CZOT), SUPRA STV-LC32T420WL (Panel LVW320CSOT E155 V2), SUPRA STV-LC32T850WL (Panel LVW320CSOT E45 V1), SUPRA STV-LC28T662WL (Panel T8-28T3520-LPM20), SUPRA STV-LC24T850WL (Panel 720p HD 1366x768), TELEFUNKEN TF-LED32S29T2 (Panel LVW320CS0T E198 V4), TELEFUNKEN TF-LED24S29T2 (Panel V236BJ1-LE2 Rev.C1), THOMSON T24E12DHU-01B T24E12DHU (Panel LVW240AUDX E2 V6).
The main features of the THOMSON T24E12DHU-01B device:
Installed matrix (LED panel) LVW240AUDX E2 V6.
To power the backlight LEDs, a converter combined with the 40-MT31BP-MAA2LG main board is used, controlled by the MP3398A PWM controller.
The power module is combined with the MainBoard and is made according to the AC / DC flyback voltage converter using PWM SOT23-6 (RT7738F) microcircuits.
MainBoard - the main board (motherboard) is a 40-MT31BP-MAA2LG module, using CPU chips: MT5531NDNT; SPI Flash: 25Q64F; SOUND: RT9108NB and others.
The ST34WN-2T-E tuner provides reception of television programs and tuning to channels.

 LED TV THOMSON T24E12DHU-01B  with LCD, diagonal size 49 "(124 cm) 16: 9 format. The declared brightness of the screen of 300 cd / m2 is provided by modern LED backlight LED. The ratio of maximum brightness to minimum (contrast) is not less 4000: 1 LCD panel uses Direct LED backlighting The design and technical capabilities of the TV allow viewing in high quality HD at a resolution of 1920x1080 pixels in graphics resolution in 1080p (Full HD). Supported media formats: MP3 , MPEG4, HEVC (H.265), Xvid, MKV, JPEG.
Speaker power of 10 W (2x5 W) is provided by two speakers. Uses the NICAM stereo signal processing system and the Sound Surround function.
External interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x2, component, VGA, HDMI x3, USB x2. A headphone jack is provided. The digital tuner has the ability to receive television channels in the DVB-T MPEG4, DVB-C, DVB-T2, DVB-S2 standards.
Overall dimensions: 1106x701x274 mm.
TV weight: 10.7 kg.
Attention! The panel of the THOMSON T24E12DHU-01B 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.