Friday 3 April 2020

REPAIR / SERVICING TV TOSHIBA 40TL938

Technical description and composition of the TOSHIBA 40TL938 TV, type of panel and applicable modules. The composition of the modules.
TOSHIBA LED
Model: 40TL938 40TL938G
Chassis / Version: PE1091
Panel: V400NK2-LS5
LED driver (backlight): T87D180.00 L460H1-2ED
Power Supply (PSU): N150A002L REV.01
PWM Power: A6069, FAN6961 (PFC), L6577B
MOSFET Power: K12A50D
MainBoard: PE1091 V28A001 434C1
IC MainBoard: MSD8881, K4B2G1646E, K4B1G1446G, TAS5708
Tuner: TDSS-G224D
Specifications 40TL938
TOSHIBA 40TL938
General repair guidelines for TV LCD LED
Possible malfunctions
- The TOSHIBA 40TL938 TV does not turn on, does not respond to the remote control and buttons on the control panel, does not light up or blink indicators.
Most likely, in this case, the main switching power supply (MPS) N150A002L is faulty. Then we recommend that you measure its output voltages and, if they are absent, you should check the health of the power switches (K12A50D) and the rectifier diodes of the converters 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.
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 A6069, FAN6961 (PFC), L6577B, in the absence of visible damage or explicit short-circuit between the terminals, are checked by replacing with new ones, or obviously working.
- There is no image, there is sound, it responds to the remote control, the channels are switched. In some cases, the image appears when you turn on and immediately disappears.
In some of these cases, the malfunction is caused by a lack of backlighting on the display. 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 indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the PE1091 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). Complex repair of MB (SSB) is possible only in the conditions of a service center with the necessary equipment. Checking or replacing elements MSD8881, K4B2G1646E, K4B1G1446G, TAS5708 requires the necessary training and professional skills in repairing modules at the component level. Problems associated with the use of BGA soldering technologies can sometimes be diagnosed by warming up.
If a TDSS-G224D tuner is suspected of malfunction, first of all, it is necessary to verify the correctness of the software, as well as the presence of the necessary supply voltage levels and data exchange pulses with the processor via the I2C bus at the corresponding tuner terminals.
TV users and owners need to remember that attempts to repair the TOSHIBA 40TL938 TV independently without the appropriate qualifications and necessary experience can lead to serious negative consequences!


FIRMWARE FOR SPI FLASH  ----------->  , EEPROM TOSHIBA 40TL938 40TL938G, Main: PE1091


 The appearance of MainBoard PE1091 is shown in the figure below:
PE1091
PE1091 can be used in TVs:
TOSHIBA 40TL968 (Panel LTA400HV04), TOSHIBA 40TL938 40TL938G (Panel V400NK2-LS5).
The appearance of the power supply
Main features of the TOSHIBA 40TL938 device:
Installed matrix (LED-panel) V400NK2-LS5.
The LED driver T87D180.00 is used to power the backlight LEDs.
The necessary supply voltages for all nodes of the TOSHIBA 40TL938 TV are generated by the N150A002L power module or its analogs using A6069, FAN6961 (PFC), L6577B microchips and K12A50D type power switches.
MainBoard - the main board (motherboard) is a PE1091 module, using microchips MSD8881, K4B2G1646E, K4B1G1446G, TAS5708 and others.
The TDSS-G224D tuner provides television reception and channel tuning.


 Brand: TOSHIBA, Model: 40TL938.
Briefly from the TV: LCD, LED backlight, 40 ", 1920x1080, 1080p Full HD, 3D, DVR, sound: 20W, HDMI: 4, Internet access, Smart TV.
The Toshiba official website has firmware (software update) for the 40TL938G (7.0.28.16.1), 40TL938F (7.0.28.16.1) models.
The composition uses MainBoard PE1091 V28A001434C1 and the LCD panel (matrix) V400NK2-LS5.
Power Supply Unit (PSU) N150A002L REV.01 Power Supply.
TOSHIBA 40TL938 LED TV with V400NK2-LS5 LCD, 40 "(102 cm) diagonal, 16: 9 format. The required brightness of the screen is 400 cd / m² with LED backlighting. Dynamic contrast ratio of 1,000,000: 1 is achieved by special control of the LEDs .This model uses side lighting from Edge LEDs.
There is support for 3D images with active (shutter) technology for separating the right and left channels. The design and technical capabilities of the TV include watching programs and movies in high quality HD at a resolution of 1920x1080 pixels in a graphical decomposition according to the standard 1080p (Full HD).
The 40TL938 is equipped with SMART software, integrated applications and the ability to work on the Internet. Connecting to the Internet can be done via Wi-Fi. The input high-frequency or video signal can be processed in analogue systems PAL, SECAM, NTSC. Graphic processing and digital signal generation occurs in standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Supported media file formats: MP3, WMA, MPEG4, Xvid, DivX, MKV, JPEG.
The power of the acoustic system of sound 20 W (2x10 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, VGA, HDMI x4, USB x2, Ethernet (RJ-45), WiDi. 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 standards.
The power consumed by the TV in the operating mode from the network is 123 watts.
Overall dimensions: with stand 923x613x215 mm, without stand 923x555x56 mm.
TV Weight: with stand: 14.5 kg, without stand: 12.5 kg.
Attention! The V400NK2-LS5 panel of a TOSHIBA 40TL938 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.