Technical description and composition of the TOSHIBA 40L1343DG TV, type of panel and applicable modules. The composition of the modules.TOSHIBA LED
Model: 40L1343DG
Chassis / Version: 17MB95
Panel: VES400UNDS-02-B
LED driver (backlight): integrated into PSU
PWM LED driver: MP3394S
MOSFET LED driver: FQD7N10L
Power Supply (PSU): 17IPS20
PWM Power: G6742HR, FAN7529
MOSFET Power: FQPF8N60C, FQPF9N50C (PFC)
MainBoard: 17MB95-2.1
IC MainBoard: MSD8WB9BX, MX25L1605A, 25Q80, H27U2G8F2CTR, TAS5719
Tuner: SI2156
Specifications 40L1343DG
TOSHIBA 40L1343DG
General repair guidelines for TV LCD LED
Possible malfunctions
- TOSHIBA 40L1343DG does not turn on and does not show any signs of operability at all. Does not blink indicators and does not respond to control buttons.
Typically, with such manifestations, the defect is caused by faulty elements in the 17IPS20 main power module. It is necessary to verify the presence of its output voltages and, if they are completely absent, check the power switches (FQPF8N60C, FQPF9N50C (PFC)) and rectifier diodes for possible short circuit.
In case of any breakdown of semiconductors in the secondary circuits, the converter can usually work normally in emergency short circuit mode. There are no output voltages. And with a short circuit in the power elements of the primary circuit, as a rule, the mains fuse breaks and less often the current sensor at the source of the key.
Breakdown of power switches (MosFet) in pulsed sources is sometimes caused by malfunctions of other circuit elements, for example, in circuits supplying a PWM controller, frequency-setting or damper ones, as well as in negative feedback (OOS) stabilization circuits. PWM controllers (PWM) G6742HR, FAN7529, if they do not have visible damage to the case and open fault between the terminals, are usually checked by replacement.
- There is no image, but there is sound and reaction to commands from the remote control. Or the image appears immediately after turning on and disappears.
A malfunction is usually most likely in these cases at the backlight nodes of the display matrix. The reason can 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 check the line of series-connected LEDs without a special current source, and for this purpose it is not safe to use any voltage sources above 12V for them. Then it remains only to open the panel and check each LED separately. Usually, Chinese 9V-powered multimeters light up a single 3-volt LED, if you connect the probes in the forward direction, the red probe to the anode, and the black to the cathode. In dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of health. In the event of a LED malfunction, its zener diode will either be cut off or broken into short-circuit.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the 17MB95-2.1 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). In cases of complex repairs of MB (SSB) and in the presence of the necessary skills and equipment, sometimes it may be necessary to replace its chips MSD8WB9BX, MX25L1605A, 25Q80, H27U2G8F2CTR, TAS5719 and other possible faulty components. Malfunctions associated with the application of BGA soldering technologies are usually easily diagnosed by the heating method.
If the TV works normally from external devices, but does not tune into television channels, the tuner SI2156 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.
Once again, we remind TV users: you should not make attempts to repair it yourself without the appropriate knowledge, experience and the necessary qualifications! Entrust repair to professionals with sufficient experience in the field of repair of electronic equipment.
SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> 17IPS20P sсhematic diagram
FIRMWARE FOR SPI FLASH -----------> TOSHIBA 40L1343DG, Main: 17MB95-2.1, Panel: VES400UNDS-02-B
Service Manuals with Schematic Diagrams 33 pages 2014 on model 40L1343DG, 40L1347DG
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 17MB95-2.1 is shown in the figure below:
17MB95-2.1
17MB95-2.1 can be used in TVs:
PHILIPS 40PFL3018T/12 (Panel VES400UNDS-01), TELEFUNKEN L32H125A3 (Panel VES315WNEA-01-B), TOSHIBA 22L1353R (Panel LM215WF4), TOSHIBA 22L1354R (Panel LM215WF4 TL G1), TOSHIBA 40L1353N (Panel LTA400HM23).
Main features of the TOSHIBA 40L1343DG device:
Installed matrix (LED-panel) VES400UNDS-02-B.
To power the backlight LEDs, a converter is used, combined with the power supply, controlled by the MP3394S PWM controller. As power elements of the LED driver, keys of the FQD7N10L type are used.
The necessary supply voltages for all nodes of the TOSHIBA 40L1343DG TV are generated by the 17IPS20 power module or its analogs using G6742HR, FAN7529 microcircuits and power switches of the FQPF8N60C, FQPF9N50C (PFC) type.
MainBoard - the main board (motherboard) is a 17MB95-2.1 module, using microchips MSD8WB9BX, MX25L1605A, 25Q80, H27U2G8F2CTR, TAS5719 and others.
The SI2156 tuner provides TV reception and channel tuning.
TOSHIBA 40L1343DG LED TV with a 40 "(102 cm) diagonal LCD display in 16: 9 format. The required screen brightness of 300 cd / m² is provided by LED backlighting. The ratio of maximum brightness to minimum (contrast) is 1400: 1. Dynamic contrast ratio of 25000: 1 is achieved by special control of the LEDs operation.This model uses side illumination from Edge LEDs.The design and technical capabilities of the TV include viewing programs and movies in high quality HD at a resolution of 1920x1080 pixels in decomposition according to the standard 1080p (Full HD). The input high-frequency or video signal can be processed in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation occurs in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p, 2160p Supported media file formats: MP3, WMA, MPEG4, Xvid, MKV, JPEG.
The power of the sound system 16 W (2x8 W) provide 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, SCART, RGB, VGA, HDMI x3, USB x2. An output for connecting headphones is provided. 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, 1280x1024, 1360x768, 1920x1080.
A digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-S2 standards.
Overall dimensions: with stand 933x603x240 mm, without stand 933x560x76 mm.
Attention! The TOSHIBA 40L1343DG LED TV panel 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.
