Technical description and composition of the SUPRA STV-LC42T662FL TV, panel type and modules used. The composition of the modules.SUPRA LED
Model: STV-LC42T662FL
Chassis / Version: MT31LB V1N03
Panel: LVF420AU0T E14 V8
LED driver (backlight): with integrated PSU
PWM LED driver: MP3394
MOSFET LED driver: AOD458
Power Supply (PSU): IPE06R41 SHG3904B-101H
PWM Power: TEA1733, MC34063
MOSFET Power: 7N65, AOD4185
MainBoard: MT31LB 40-T31T0T-MAB2HG
IC MainBoard: SPI Flash W25Q64FVSIG
Tuner: RF221ZN V4D17AA
STV-LC42T662FL Specifications
SUPRA STV-LC42T662FL
General recommendations for TV LCD LED repair
Repair of the SUPRA STV-LC42T662FL TV should begin with a careful external examination of all its components and modules. Based on visible external changes in the state of components, it is usually possible to determine the further direction of troubleshooting and localization of a defect before taking the necessary measurements. If ring cracks are found in the soldering of the terminals of the elements or broken connecting tracks, swollen capacitors or charred resistors - all this may be characteristic signs of the causes or consequences of an already known typical malfunction.
If the power supply module fails, external manifestations may be different, for example, SUPRA STV-LC42T662FL does not turn on at all and there is no indication of the control lamps on the front panel. With the same symptoms, the regulator (converter) of the control processor power supply may be faulty. In the absence of swollen capacitors of the secondary rectifier filter, diagnostics of the power supply should begin with checking the fuse and, if it breaks, it is necessary first of all to check all power semiconductor elements of the primary circuit - diodes and transistors for the likelihood of an avalanche or thermal breakdown.
If a breakdown of the power switch is detected, it should be remembered that in a switching power supply (SMPS) it does not fail by itself without reasons that should be looked for by checking other elements of the primary circuit - electrolytic capacitors, a PWM controller, which can only be checked replacement, as well as other semiconductor elements (diodes, transistors, zener diodes).
If SUPRA STV-LC42T662FL has no picture, but there is sound and the TV is controlled from the remote control, a malfunction is likely in the LVF420AU0T E14 V8 panel backlight circuits. The LEDs or the power converter - LED driver may be faulty. Often in such cases, when the TV is turned on, an image appears and immediately disappears. First of all, you need to make sure that the electrolytic capacitors of the rectifier filter supplying the LED driver are in good working order, and check the LEDs by connecting those that are known to be working for diagnostics.
In most cases when there is no backlight, it becomes necessary to disassemble the panel in order to check the LEDs, connectors, loops and all contact connections. If one or more LEDs do not work in one line, therefore, they are punctured and should be replaced.It is impossible to check the LED bars for a break without disassembling the panel with a multimeter or tester. For these purposes, it is necessary to open all series-connected PN junctions and a voltage of the order of tens of volts will be required, and ideally a current source.
If the 40-T31T0T-MAB2HG MT31LB motherboard is faulty, first of all, you need to check all the linear stabilizers or power converters of its chips, and also, if necessary, update the software. Sometimes it is possible to check the health of the MB only by replacing it.
Complex repair of MB (SSB) is possible only in the conditions of a service center with the necessary equipment. Checking or replacing SPI Flash W25Q64FVSIG elements requires the necessary training and professional skills to repair modules at the component level. Problems associated with BGA soldering technologies can be diagnosed by the warm-up method.
If there is no reception of television channels, but the TV is working properly from external devices, first of all, you need to check the supply voltage of the RF221ZN V4D17AA tuner.
Remember! Attempts to repair the SUPRA STV-LC42T662FL TV, in the absence of the necessary qualifications and experience, are categorically not recommended and are fraught with negative consequences, up to the complete non-repairability of the device!
DOWNLOAD FIRMWARE FOR SPI FLASH -----------> SUPRA STV-LC42T662FL, Main: 40-T31T0T-MAB2HG MT31LB, Panel: LVF420AU0T E14 V8.
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL Power supply circuit -----------------> IPE06R41
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).
TV LED IC MP3394/MPS3394S LED Driver Diagnostics Throubleshooting
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 RepairThe appearance of the MainBoard MT31LB is shown in the figure below:
MT31LB
External view of the power supply
Main features of SUPRA STV-LC42T662FL device:
Installed matrix (LED panel) LVF420AU0T E14 V8.
A converter combined with a power supply is used to power the backlight LEDs, and is controlled by the MP3394 PWM controller. The keys of the AOD458 type are used as power elements of the LED driver.
The formation of the necessary supply voltages for all nodes of the SUPRA STV-LC42T662FL TV is carried out by the IPE06R41 power module, or its analogs using TEA1733, MC34063 microcircuits and power switches of the 7N65, AOD4185 type.
MainBoard - the main board (motherboard) is an MT31LB module, using SPI Flash W25Q64FVSIG chips and others.
The RF221ZN V4D17AA tuner provides reception of television programs and tuning to channels.
SUPRA LED TV STV-LC42T662FL with LCD LVF420AU0T, 42 "(107 cm) 16: 9. depending on the illumination of the areas in the scene.This model uses an LED-panel with an edge LED backlighting - Edge LED.Possibilities of the TV provide viewing of broadcasts and films in high quality HD at a resolution of 1920x1080 pixels in graphics decomposition at 1080p (Full HD). The input high-frequency or video signal is decoded in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal shaping occurs in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Supported media file formats: MP3, WMA, MPEG4, MKV, JPEG.
Speaker power of 16 W (2x8 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, VGA, HDMI x2, USB. A headphone output is provided. 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 television channels in the DVB-T, DVB-C, DVB-T2 standards.
Overall dimensions: 1155x762x164 mm.
Attention! The panel LVF420AU0T E14 V8 of the SUPRA STV-LC42T662FL 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.