Technical description and composition of the SUPRA STV-LC40T850FL TV, panel type and modules used. The composition of the modules.SUPRA LED
Model: STV-LC40T850FL
Chassis / Version: MT31LB
Panel: LVF390CMOT // V390HJ1-LE2
LED driver (backlight): integrated into PSU
PWM LED driver: MP3394
MOSFET LED driver: APM1105NU
Power Supply (PSU): SHG3203B-101H DLBB253
PWM Power: OB5269,
MOSFET Power: 6N60
MainBoard: 40-T31TOT-MAB2HG
IC MainBoard: CPU: MT5531NDNT, SPI FLASH: GD25Q64
Tuner: RF221ZN V4D17AA
STV-LC40T850FL Specifications
SUPRA STV-LC40T850FL
General recommendations for TV LCD LED repair
Possible malfunctions
- SUPRA STV-LC40T850FL TV does not turn on at all. No response to the remote control and front panel control buttons. Indicator lamps do not light up or flash.
Usually with similar manifestations, the defect is caused by faulty elements in the main power module SHG3203B-101H. Its output voltages should be measured and, in their absence, the serviceability of the power switches (6N60) and rectifier diodes in the converters should be checked for possible breakdown.
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) OB5269, if they do not have visible damage to the case and an open short circuit between the terminals, are usually checked by replacing.
- There is no picture, but there is sound, it reacts to the remote control. Or the image appears when turned on and disappears immediately
A malfunction is usually in these cases most likely in the backlight units of the display matrix. Often the cause of a malfunction is the lack of current in the LED circuit, for example, their open or short circuit, or a violation of the contact connections of the connectors.
To test the LED strips, to open all the transitions of the LEDs, you need several tens of volts or more, 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 requires replacement.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals the standby mode.
Repair or diagnostics of the 40-T31TOT-MAB2HG 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). In cases of complex MB (SSB) repairs and with the necessary skills and equipment, it may sometimes be necessary to replace its CPU chips: MT5531NDNT, SPI FLASH: GD25Q64 and other possible faulty components. Malfunctions associated with the use of BGA soldering technologies are usually easily diagnosed by the warm-up method.
If you suspect a malfunction of the RF221ZN V4D17AA tuner, first of all, you need to make sure that the software is correct, as well as the presence of the required levels of supply voltages and pulses of data exchange with the processor via the I2C bus at the corresponding tuner pins.
Users and owners of TVs need to remember that attempts to self-repair a SUPRA STV-LC40T850FL TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!
DOWNLOAD FIRMWARE FOR SPI FLASH -----------> SUPRA STV-LC40T850FL, Main: MT31BL, Panel: 1080p Full HD, 1920x1080
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> SHG3203B-101H Power supply
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).
The earlier MP3394 was replaced by MPS3394S, which is an upgraded version of the same IC, and found in the 17IPS20 power supply board. It is the main heart of the backlighting LED drive and the failure of this IC can cause the TV not to start. This is a voltage step-up IC that takes 5-V to 28-V at its input pin 15 (Vin) and raises it to drive four independent strings of LEDs. It also performs other functions such as voltage regulation between the LED strings, and provides a dimming facility using pulse-width modulation (PWM). An important aspect of this IC is that it has built-in open and short LED protection circuitry. It is also able to sense the current and voltage of the LED matrix load and determine abnormal conditions. That means that if all the LEDs in the matrix go open or short, it will prevent the television from switching ON.
The IC has internal control logic that produces the GATE signal to drive an external MOSFET transistor. This is the transistor that is switched against an inductor to step-up the voltage, and the gate signal is produced only when the internal control logic detects normal conditions. It is able to determine normal/abnormal conditions through internal comparators, and one such is the LED Over-Voltage Protection (LED OVP) comparator that provides Short String Protection (SSP).
When the TV is switched ON, this IC is enabled through pin 2, by a voltage greater than 1.8-V. It first checks the circuit configuration, and then checks the over-voltage protection signal at (pin 12) to determine if the rectifier diode is open and whether the booster MOSFET (driven by the GATE signal) is short to ground. If the OVP voltage at pin 12 is lower than 70-mV (may be different for other board versions), then it disables itself and the TV will not start.
On the 17IPS20 board, the GATE signal is known as GATE_LED, which drives a bi-polar junction transistor (BJT) Q500 (BC858B). This transistor then drives Q502/Q503 MOSFET booster group of transistors to step-up the voltage (shown in the following pages of this article). In this circuit configuration the inductance coils are L500 and L501. The high voltage produced then goes into a group of rectifier diodes D503 and D504 producing a positive DC voltage for the LEDs. The over voltage protection signal is known as OVP_LED. Whilst all the LED strings take their power from this positive voltage source, they all have separate independent drain pins through the MPS3394S controller IC.
There are also other parameters to consider such as Under-Voltage Lock-Out (UVLO), which is determined by measuring the rising-edge of Vin. This parameter has to be between 3.5-V and 4.4-V, with 3.9-V being the typical value. It is a very clever IC as it can also detect open and short LED strings in the backlight array.
Although this diagnostic cannot tell you the condition of each individual diode, it can indicate the condition of each string of diodes in the backlight matrix. The MPS3394S IC (SOIC16 package) drives four separate strings of LEDs through dedicated open drain output pins. LED string 1 is driven by pin 11, LED string 2 by pin 10, LED string 3 by pin 9, and LED string 4 by pin 8. It also monitors the voltages at these pins so that if there was a shorted LED in one of the strings then it would disconnect that string. If the voltage at any of these pins is greater than 6.1-V, then this condition triggers the short circuit protection mechanism for disconnecting the string at that pin. It is also possible to determine an open string, and in this case, this condition is detected when the pin voltage is lower than 196-mV.
Interestingly, this IC is designed such that it will always try to light at least one string if it is working. The only time when the step-up converter shuts-down completely is if all the strings were either open, or short. Therefore, before you rush off to eBay to buy a new chip, measure the voltages at these pins to make sure that the diodes are not faulty. Otherwise, you will end up wasting a lot of time and money!
Additional MainBoard Repair
The appearance of the MainBoard 40-T31TOT-MAB2HG is shown in the figure below:
40-T31TOT-MAB2HG
40-T31TOT-MAB2HG can be used in TVs:
ERISSON 32LET40 (Panel LVW320CSOT E45 V11 T8-32T3510-LPM8), ERISSON 28LET40 (Panel LVW280CSOT E19 V2), FUSION FLTV-24T25 (Panel LVW240CMOT E12 V6), MYSTERY MTV-3227LT2 (Panel LVW320CSOT E45 V11 720p HD 1366x768), MYSTERY MTV-4225LT2 (Panel LVF420CMOT - E18.V1), SUPRA STV-LC32T662WL (Panel LWV320CSOT E45 V16 (T8-32T3520-LPM10)).
External view of the power supply
Main features of SUPRA STV-LC40T850FL device:
Installed matrix (LED panel) LVF390CMOT or V390HJ1-LE2.
A converter combined with a power supply is used to power the backlight LEDs, and is controlled by the MP3394 PWM controller. APM1105NU keys are used as power elements of the LED driver.
The formation of the necessary supply voltages for all nodes of the SUPRA STV-LC40T850FL TV is carried out by the SHG3203B-101H power module, or its analogs using OB5269 microcircuits, and 6N60 type power switches.
MainBoard - the main board (motherboard) is a 40-T31TOT-MAB2HG module, using CPU chips: MT5531NDNT, SPI FLASH: GD25Q64 and others.
The RF221ZN V4D17AA tuner provides reception of television programs and tuning to channels.
SUPRA LED TV STV-LC40T850FL with LCD LVF390CMOT, 39 "(99 cm) diagonal, 16: 9 format. The required brightness of 320 cd / m² is provided by LED backlighting. Dynamic contrast ratio of 100,000: 1 is achieved by special LED control depending on the illumination of the areas in the scene. The display technology of the model uses LED LED backlight. The capabilities of the TV provide viewing of broadcasts and movies in high quality HD at a resolution of 1920x1080 pixels in graphic decomposition according to the standard 1080p (Full HD). The input high-frequency or video signal is decoded into analog systems PAL, SECAM, NTSC Graphic processing and digital signal shaping takes place in 480i, 480p, 576i, 576p, 720p, 1080i, 1080p 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, a VGA (D-Sub 15) connector on the TV case is used, this interface supports resolutions: 640x480, 800x600, 1024x768, 1360x768, 1920x1080. The digital tuner is capable of receiving TV channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Dimensions: With stand 887x585x225 mm, Without stand 887x530x60 mm.
TV weight: 11.6 kg.
Attention! The LVF390CMOT panel of the SUPRA STV-LC40T850FL 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 unrepairable ................................ .............
