Technical description and composition of the TOSHIBA 32S2750EV TV, type of panel and applicable modules. The composition of the modules.TOSHIBA LED
Model: 32S2750EV
Chassis / Version: MSD3463-T8C1
Panel: K320WD92
LED backlight: 4708-K320WD-A4213K01
LED driver (backlight): integrated into MainBoard; 300 mA
PWM LED driver: MP3394S
MOSFET LED driver: AOD256
Power Supply (PSU): integrated into MainBoard
PWM Power: OB5269CP
MOSFET Power: AOTF10N65
MainBoard: MSD3463-T8C1
IC MainBoard: CPU: MSD3463-GSA, SPI FLASH: MX25L6406, AUDIO: TPA3110D2
Tuner: SI2151
Specifications 32S2750EV
TOSHIBA 32S2750EV
General repair guidelines for TV LCD LED
Possible malfunctions
- TOSHIBA 32S2750EV does not turn on and does not show any signs of performance at all. Does not blink indicators and does not respond to control buttons.
In such cases, the AC / DC voltage converter, which is combined with the main board MSD3463-T8C1, is often faulty. It is then necessary to measure its output voltages and, if they are absent, you should check the power switches (AOTF10N65) and the rectifier diodes of the converters for a short circuit probability.
In case of breakdowns of semiconductors in the secondary circuits of any converter, as a rule, it can operate in emergency short-circuit mode without output voltages, and during short circuit in the elements of the primary circuit, the main fuse and, less often, the current sensor at the source of the key are most often cut off.
Mos-Fet power switches, used in switching power supplies, sometimes fail due to a malfunction of any other elements that can put it out of operation in key mode or create an excess of the maximum permissible parameters of the switch. These can be elements supplying the PWM controller, frequency-setting or damping circuits, or negative feedback elements in the stabilization circuit. PWM controllers OB5269CP, in the absence of visible damage or explicit short-circuit between the terminals, are checked by replacing with new, or obviously working.
- There is no image, there is sound, all other functions of the TV work. When turned on, the image may sometimes appear for a second.
Usually in such cases, a malfunction is detected in the backlight nodes of the LED panel. The reason can sometimes be in the power of the LEDs, but more often in their malfunction (breakdown or break), sometimes in the violation of the contact connections of the LED strips.
To check the LED lines for breaks without disassembling the panel, for example, a current source will help. It is impossible to open series-connected PN junctions with a simple multimeter, a voltage of the order of several tens of volts is required.
- The indicator on the front panel blinks, the TV does not turn on in the operating mode, it does not respond to the remote control.
Repair or diagnostics of the MSD3463-T8C1 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). Board repair and replacement of CPU chips: MSD3463-GSA, SPI FLASH: MX25L6406, AUDIO: TPA3110D2 are carried out with the necessary equipment, and the corresponding element base. Faults associated with the application of BGA processor soldering technologies can be localized by the heating method.
If the TV works normally from external devices, but does not tune into television channels, the SI2151 tuner may be malfunctioning. In such cases, first of all, you should make sure that there are supply voltages at its corresponding conclusions. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus. Sometimes the cause of the inoperability of the tuner may be a software failure.
Attention to users! Self-repair of the TOSHIBA 32S2750EV TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> MainBoard (Chassis) MSD3463-T8C1
FIRMWARE FOR SPI FLASH -----------> TOSHIBA 32S2750EV, Main: MSD3463-T8C1, Panel: K320WD92
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!
To reduce the backlight current in LED drivers with the MP3394S (MP3394) controller, increase the resistance of the resistor from pin 6 (ISET) to the chassis. The maximum current in each channel (in milliamperes) for the Rset resistor (in kilo-ohms) is determined from the ratio 790 * 1.23V / (Rset + 0.4).Repair MainBoard
The appearance of the MainBoard MSD3463-T8C1 is shown in the figure below:
MSD3463-T8C1
MSD3463-T8C1 can be used in TVs:
PHILIPS 32PHT4001/60 (Panel K320WD92), PHILIPS 43PFT4001/60 (Panel K430WD9), TELEFUNKEN TF-LED39S35T2 (Panel K390WD5 K390WD5UB280H200), TELEFUNKEN TF-LED32S35T2 (Panel K320WD5).
Key Features of the TOSHIBA 32S2750EV:
Installed matrix (LED-panel) K320WD92.
To power the backlight LEDs, a converter is used, combined with the main board MSD3463-T8C1, controlled by the MP3394S PWM controller. As the power elements of the LED driver, keys of the AOD256 type are used.
The power module is combined with the MainBoard and is made according to the flyback AC / DC voltage converter circuit using OB5269CP microcircuits and AOTF10N65 type power switches.
MainBoard - the main board (motherboard) is an MSD3463-T8C1 module, using CPU chips: MSD3463-GSA, SPI FLASH: MX25L6406, AUDIO: TPA3110D2 and others.
The tuner SI2151 provides reception of television programs and tuning to channels.
Brand: TOSHIBA, Model: 32S2750EV.
Briefly from the TV: LCD, LED backlight, 32 ", 1366x768, 720p HD, DVR, sound: 16W, HDMI connectors: 3.
Manufacturer: TELEBALT plant Kaliningrad, st. Kamskaya, house 62 (licensed by Dolby Laboratories).
Developer: Toshiba Corporation. Japan
The composition uses MainBoard MSD3463-T8C1 and LCD-panel K320WD92. The power supply is combined with the MainBoard.
TOSHIBA 32S2750EV LED TV with K320WD92 LCD, 32 "(81 cm) diagonal size in 16: 9 format. The required brightness of the screen is 240 cd / m² LED backlighting. The ratio of maximum brightness to minimum (contrast) is 1200: 1 LED display technology is implemented in the manufacturing technology of this model’s display. HD images can be viewed in high resolution at 1366x768 pixels in the standard of graphic decomposition 720p (HD Ready). Supported media file formats: MP3, MPEG4, HEVC (H.265), MKV , JPEG.
The power of the sound speaker system 16 W (2x8 W) is provided by two speakers. It uses a NICAM stereo signal processing system and Sound Surround.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, component, VGA, HDMI x3, MHL, USB x2. An output for connecting headphones is provided.
A digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Overall dimensions: with stand 730x467x176 mm, without stand 730x435x76 mm.
TV Weight: with stand: 4.5 kg, without stand: 4.4 kg.
Attention! The K320WD92 panel of the TOSHIBA 32S2750EV LED TV 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.