Friday 3 April 2020

REPAIR / SERVICING TV TOSHIBA 40L5455R

Technical description and composition of the TOSHIBA 40L5455R TV, type of panel and applicable modules. The composition of the modules.
TOSHIBA LED
Model: 40L5455R
Chassis / Version: 17MB95M
Panel: VES400UNVS-3D-N01
LED backlight: 40lnch VNB 7020PKG 60EA Rev0.2 140 122 (METALSAN BRACKET AL 40262)
T-CON: 3VNB_FP_SQ60MB4C4LV0.0
LED driver (backlight): integrated into PSU
PWM LED driver: MP3394
MOSFET LED driver: FQD7N10L
Power Supply (PSU): 17IPS71
PWM Power: FAN6300
MOSFET Power: FQPF8N60C
MainBoard: 17MB95M
IC MainBoard: MT5820LUNU, 25L1605, H27U2G8F2CTR-BC, H5TQ2G63DFR
Control: Wi-Fi: 17WFM03 TWFM-L001D, IR: 17LD159
Specifications 40L5455
TOSHIBA 40L5455R
General repair guidelines for TV LCD LED
Possible malfunctions
- TOSHIBA 40L5455R does not turn on, the indicators on the front panel do not light or flash. The TV does not respond to the control buttons and the remote control.
In some of these cases, the main switching power supply, the 17IPS71 module, is faulty. It is necessary to measure its secondary output voltages, and if they are absent, check the power switches (FQPF8N60C) and rectifier diodes in the converters for a short circuit.
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 mains fuse and, less often, the current sensor at the source of the key are most often cut off.
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. FAN6300 PWM controllers (PWMs), if they do not have visible damage to the chassis and open short-circuit 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.
When diagnosing, it is necessary to take into account that it is impossible to check the open in the chain of LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally, a current source. By opening the panel, each LED can be checked separately. Typically, Chinese multimeters light up a single 3-volt LED, if you connect probes in the forward direction to it. 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 enter the operating mode, does not respond to the remote control. The indicator on the front panel lights constantly or blinks.
Repair or diagnostics of the 17MB95M 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 chip replacement MT5820LUNU, 25L1605, H27U2G8F2CTR-BC, H5TQ2G63DFR are made with the necessary equipment, and the corresponding hardware base. Faults associated with the application of BGA processor soldering technologies can be localized by the heating method.
Attention to users! Independent repair of the TOSHIBA 40L5455R TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!


SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    17IPS71-R3 Power supply


 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 17MB95M is shown in the figure below:
17MB95M
17MB95M can be used in TVs:
TOSHIBA 40L5455R (Panel VES400UNVS-3D-N01), TOSHIBA 40L5435 40L5435DG (Panel VES400UNVS-3D-N01).
The appearance of the power supply
Main features of the TOSHIBA 40L5455R device:
Installed matrix (LED-panel) VES400UNVS-3D-N01.
The matrix control uses the Timing Controller (T-CON) 3VNB_FP_SQ60MB4C4LV0.0.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the MP3394 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 40L5455R TV are generated by the 17IPS71 power supply module or its analogs using FAN6300 microcircuits and power switches of the FQPF8N60C type.
MainBoard - the main board (motherboard) is a 17MB95M module, using chips MT5820LUNU, 25L1605, H27U2G8F2CTR-BC, H5TQ2G63DFR and others.

 Brand: TOSHIBA, Model: 40L5455.
Short from TV: LCD, LED backlight, 40 ", 1920x1080, 1080p Full HD, 3D, DVR, sound: 16W, HDMI: 3, Internet access, Wi-Fi, Smart TV.
The composition uses MainBoard 17MB95M and an LCD panel (matrix) VES400UNVS-3D-N01.
Power Supply Unit (PSU) 17IPS71 Power Supply.

 TOSHIBA 40L5455 LED TV with VES400UNVS-3D-N01 LCD, 40 "(102 cm) diagonal of 16: 9 format. The required screen brightness of 300 cd / m² is provided by LED backlighting. The ratio of maximum brightness to minimum (contrast) makes 4000: 1. Dynamic contrast ratio of 30000: 1 is reached by special control of work of light-emitting diodes. In this model lateral illumination from Edge LEDs is used.
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 40L5455 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, DivX, 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, HDMI x3, USB x2, Ethernet (RJ-45), Wi-Fi, 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, DVB-T2 standards.
The power consumed by the TV in the operating mode from the network is 76 watts.
Overall dimensions: with stand 925x604x250 mm, without stand 925x551x68 mm.
TV Weight: with stand: 14 kg, without stand: 11 kg.
Attention! The VES400UNVS-3D-N01 panel of the TOSHIBA 40L5455 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.