REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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Saturday, 11 July 2020

REPAIR / SERVICING TV SUPRA STV-LC24T850WL

Technical description and composition of the TV SUPRA STV-LC24T850WL, type of panel and applicable modules. The composition of the modules.
SUPRA LED
Model: STV-LC24T850WL
Chassis / Version: V1N10
Panel: 720p HD 1366x768
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP3398A
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6 (RT7738)
MainBoard: 40-MT31BP-MAA2LG
IC MainBoard: CPU: MT5531NDNT; SPI Flash: 25Q64F; SOUND: RT9108NB
Tuner: ST34WN-2T-E
Technical Specifications STV-LC24T850WL
SUPRA STV-LC24T850WL
General repair guidelines for TV LCD LED
If the SUPRA STV-LC24T850WL TV does not turn on. No control lights on the front panel are lit or blinking, the TV does not respond to the remote control and does not make any sounds or any signs of life when turned on. The most likely cause of the malfunction is a failure of the common power module, which is integrated into the MainBoard. When repairing the power supply unit, it is advisable to start the diagnostics by checking the mains fuse and the electrolytic capacitors of the filters of the converter secondary rectifiers. In the event of a fuse breaking, the reason should be sought in the power semiconductor elements of the pulse converter of the main power supply. First of all, it is necessary to check the diodes of the bridge of the rectifier of the mains voltage and the power key (s) of the converter. The complete inoperability of the power supply unit can be caused by a short circuit of the power elements in the primary circuit, followed by an open fuse, or a short circuit in the loads.
The reasons for the breakdown of the power switch in pulsed power supplies (IIPS) can be different, for example, a malfunction of semiconductor elements or electrolytic capacitors in the stabilization circuits of the primary circuit, as well as a failure in the operation of the PWM controller chip or broken resistors in its bundle.
If there is no image when you turn on the SUPRA STV-LC24T850WL, or it appears and immediately disappears, but there is sound, most likely a malfunction in the backlight LED circuit of the 1366x768 720p HD panel, or in the LED node of the driver-converter of their power supply.
To check the health of the LEDs and contact connections in their power circuit, the panel must be disassembled.
To check the health in the LED circuit, it is better to use a current source with a maximum voltage of 200V. We do not recommend using any voltage sources for this purpose. You can test each LED individually with a simple Chinese multimeter (powered by 9 volts) in the P-N-junction test mode. If you connect the red probe of the multimeter to the anode of the LED, and the black to its cathode, then the LED will light up slightly.
Repair or diagnostics of the 40-MT31BP-MAA2LG motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update the software (software).
In some cases, they require checking or replacing (if necessary) the elements of the MB board (SSB) - CPU: MT5531NDNT; SPI Flash: 25Q64F; SOUND: MP3398A. In cases where the BGA processor is used, its malfunction is usually detected by the local heating method.
If there is no reception of television channels, but the TV is working properly from external devices, first of all, check the voltage of the CPU tuner: MT5531NDNT; SPI Flash: 25Q64F; SOUND: MP3398A and update the software.
Owners and users of the SUPRA STV-LC24T850WL TV must remember that self-repair without special knowledge, skills and qualifications can be fraught with negative consequences that can lead to complete non-repairability of the device!


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).
Main features of the SUPRA STV-LC24T850WL device:
Installed matrix (LED-panel) 720p HD 1366x768.
To power the backlight LEDs, a converter is used, combined with the main board 40-MT31BP-MAA2LG, controlled by the MP3398A PWM controller.
The power module is combined with the MainBoard and is made according to the flyback AC / DC voltage converter circuit using PWM SOT23-6 (RT7738) 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 TV reception and channel tuning.
LED TV SUPRA STV-LC24T850WL with LCD display V240AE1N01-1, diagonal size 24 "(61 cm) 16: 9 format. The required brightness of the screen 280 cd / m² is provided by LED backlight LED. Dynamic contrast ratio 60000: 1 is achieved by special control LEDs work depending on the light in the plot. The model’s display technology uses LED LED backlighting. You can watch broadcasts and movies and images in high quality HD at a resolution of 1366x768 pixels in the standard of graphic decomposition 720p (HD Ready). The input high-frequency or video signal is decoded in analogue systems PAL, SECAM, NTSC. Graphic processing and digital signal generation occurs in standards 480i, 480p, 576i, 576p, 720p, 1080i. Supported media file formats: MP3, MPEG4, Xvid, DivX, MKV, JPEG. Stereo sound is realized in two built-in speakers using NICAM STEREO audio processing system.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x2, component, SCART, RGB, VGA, HDMI x2, MHL. To connect a computer or laptop to this TV model, a VGA (D-Sub 15) connector is used on the TV case, this interface supports resolutions: 640x480, 800x600, 1024x768, 1360x768. A digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Overall dimensions: With a support 583x418x159 mm, Without a support 583x377x56 mm.
TV Weight: 4 kg.
Attention! The panel of the V240AE1N01-1 LED TV SUPRA STV-LC24T850WL is an expensive and unreliable element.
Avoid any impact on the glass and pressure on the surface of the screen to avoid damage to the LED panel!
It is also unsafe to get liquid on the screen. Sometimes one drop is enough if it flows down the glass onto the cables so that the TV becomes unrepairable.