Technical description and composition of the SUPRA STV-LC28T850WL TV, panel type and modules used. The composition of the modules.SUPRA LED
Model: STV-LC28T850WL
Chassis / Version: V1M12 MT31LB
Panel: LVW280CSOT E8 V1
T-CON: MT3151A05-3-XC-1 ST2751A01-4
LED driver (backlight): integrated into PSU
PWM LED driver: MP3394S
MOSFET LED driver: APM1105N, AOD442
Power Supply (PSU): SHG3206A-101H
PWM Power: OB5269CP, MC34063A
MainBoard: MT31LB (40-T31T0T-MAB2HG)
IC MainBoard: Spi Flash: Winbond 25Q64, AUDIO: STA381BW
Tuner: RF221ZN V4D17AA
STV-LC28T850WL Specifications
SUPRA STV-LC28T850WL
General recommendations for TV LCD LED repair
Possible malfunctions
- SUPRA STV-LC28T850WL TV does not turn on at all. Control lamps do not light up or blink. The TV on the remote control and control panel buttons does not respond.
With such manifestations, a malfunction is most likely found in the SHG3206A-101H power module. 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 of semiconductors in the secondary circuits, the converter can usually operate in an emergency in the short-circuit mode, and in the event of a short-circuit in the power elements of the primary circuit, the mains fuse often breaks.
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 a PWM regulator, in frequency-setting or damper circuits, as well as in negative feedback stabilization. PWM microcircuits (PWM) OB5269CP, MC34063A are usually checked by replacing them with new ones, or knowingly working properly.
- There is no image, there is sound, it reacts to the remote control. Or, immediately after switching on for a second, the image may appear and immediately disappear.
In some of these cases, the malfunction is caused by the lack of display backlighting. 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.
It is impossible to detect a break in the LED line without disassembling the panel with a simple multimeter. The LEDs are connected in series and a voltage of several tens of volts is required to open their junctions. Ideally, a current source is suitable for such purposes. You can open the panel and check each LED separately. Usually, Chinese multimeters lightly light up one 3-volt LED if you connect the probes to it in the forward direction (red probe to the anode, black to the cathode). 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 into 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 MT31LB motherboard should begin with checking the stabilizers and power converters necessary to power the microcircuits and matrix. If necessary, you should update or replace the software (software). In cases of complex MB (SSB) repairs and with the necessary skills and equipment, it may sometimes be necessary to replace its Spi Flash chips: Winbond 25Q64, AUDIO: STA381BW and other possible faulty components. Malfunctions associated with the use of BGA soldering technologies are usually easily diagnosed by the warm-up method.
Before changing the RF221ZN V4D17AA 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
We remind users again! Attempts to self-repair the SUPRA STV-LC28T850WL TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
DOWNLOAD FIRMWARE FOR SPI FLASH -----------> SUPRA STV-LC28T850WL, Main: MT31LB (40-T31T0T-MAB2HG), Panel: LVW280CSOT E8 V1
To reduce the backlight current in LED drivers with an MP3394S (MP3394) controller, increase the resistance of the resistor from pin 6 (ISET) to the case. The maximum current in each channel (in milliamperes) for the resistor Rset (in kilo-ohms) is determined from the ratio 790 * 1.23V / (Rset + 0.4).
Additional MainBoard RepairThe appearance of the MainBoard MT31LB is shown in the figure below:
MT31LB
External view of the power supply
Main features of SUPRA STV-LC28T850WL device:
Installed matrix (LED-panel) LVW280CSOT E8 V1.
Matrix control uses Timing Controller (T-CON) MT3151A05-3-XC-1.
To power the backlight LEDs, a converter combined with a power supply is used, controlled by the MP3394S PWM controller. As the power elements of the LED driver, keys of the APM1105N, AOD442 types are used.
The formation of the necessary supply voltages for all nodes of the SUPRA STV-LC28T850WL TV is carried out by the SHG3206A-101H power module, or its analogs using OB5269CP, MC34063A microcircuits.
MainBoard - the main board (motherboard) is an MT31LB module, using Spi Flash chips: Winbond 25Q64, AUDIO: STA381BW and others.
The RF221ZN V4D17AA tuner provides reception of television programs and tuning to channels.
LED TV SUPRA STV-LC28T850WL with LCD LVW280CSOT, 28 "(71 cm) 16: 9. depending on the illumination of the areas in the scene. The display technology of the model uses LED backlighting. It is possible to view broadcasts and films and images in high quality HD at a resolution of 1366x768 pixels in the 720p (HD Ready) graphics standard. Input high-frequency or video signal is decoded in analog PAL, SECAM, NTSC systems Graphic processing and digital signal formation is performed in 480i, 480p, 576i, 576p, 720p, 1080i standards Supported multimedia file formats: MP3, MPEG4, Xvid, DivX, MKV, JPEG.
Speaker power 10 W (2x5 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
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, use the VGA (D-Sub 15) connector on the TV case, this interface supports resolutions: 640x480, 800x600, 1024x768, 1360x768. The digital tuner is capable of receiving TV channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Dimensions: With stand 646x443x199 mm, Without stand 646x398x61 mm.
TV weight: 5.2 kg.
Attention! The panel LVW280CSOT E8 V1 of the SUPRA STV-LC28T850WL LED TV is an expensive and unreliable element.
Do not allow any impacts 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 non-repairable.