Saturday 4 April 2020

REPAIR / SERVICING TV TOSHIBA 46VL748R


Technical description and composition of the TOSHIBA 46VL748R TV, type of panel and applicable modules. The composition of the modules.
TOSHIBA LED
Model: 46VL748R
Panel: LTA460HJ11 T01
T-CON: PE0893 V28A1168A1
LED driver (backlight): V71A00017700 PSLF211402A
Power Supply (PSU): V71A00017700 PSLF211402A
MainBoard: PE0887 V28A001177A1
IC MainBoard: ZR30011BGCG,
Tuner: ENGS7301D
Specifications 46VL748
TOSHIBA 46VL748R
General repair guidelines for TV LCD LED
Diagnostics of malfunctions and repairs of the TOSHIBA 46VL748R, as well as other electronic devices, it is recommended to start with an external examination of the external and internal elements. Specific external damage to some elements can sometimes indicate further actions to determine the malfunction of the TV and localize the defect before the necessary measurements are taken. If ring cracks are detected in the soldered terminals of the elements or dangling connecting tracks, swollen capacitors or charred resistors - all this can be characteristic signs of the causes or consequences of an already known typical malfunction.
If the TOSHIBA 46VL748R does not turn on, no control lights on the front panel light up or blink, therefore, there is a very high probability of a malfunction of the V71A00017700 PSLF211402A power module. In some cases, only the processor power regulator may be faulty. Diagnostics and repair of the common power supply should always begin with a check of the mains fuse and the condition of the electrolytic capacitors of the secondary rectifier filters. Defective and swollen capacitors should be replaced with new ones. If the fuse is broken, it is advisable to check for a breakdown, first of all, all the power semiconductor elements of the converter and the diode bridge of the rectifier network, as well as the large electrolytic capacitor of the filter of the rectifier network.
The reasons for the breakdown of the power switch in pulsed power supplies (IIPS) can be different, for example, a malfunction of semiconductor cells or electrolytic capacitors in the stabilization circuits of the primary circuit, as well as a failure in the operation of the PWM controller chip or broken resistors in its bundle.
Sometimes the TOSHIBA 46VL748R TV does not have an image, but there is sound, or the image appears and immediately disappears. In this case, there is a high probability of a malfunction of the LTA460HJ11 T01 panel backlight LED converter, or a break in the LED circuit is possible. In such cases, first of all, it is necessary to verify the serviceability of all the electrolytic capacitors of the filter by supplying the LED driver itself, including in the power supply unit (power supply unit).
Often there is a need for disassembling the panel to check the health of the LEDs, as well as contact connections in the connectors and soldering.
To detect a break in the LED lines without disassembling the panel, a current source is required. It is impossible to open transitions connected in series with a simple multimeter; voltage of several tens of volts is necessary.
Diagnostics and repair of the motherboard PE0887 V28A001177A1 is carried out by checking the performance of the stabilizers or power converters of the module chips. In some cases, a software update is required.
When repairing an MB board, you must check its components ZR30011BGCG,. Defective items should be replaced. If BGA chips are installed, their malfunction is usually localized by heating. If chips with BGA soldering technology are used, a problem in its implementation is detected by the local heating of the chip.
Before changing the ENGS7301D tuner, if it is not possible to tune to television channels, make sure that there are supply voltages, including varicap power (30-33V), which must be measured on the corresponding tuner pins.
Remember! Attempts by users to repair the TOSHIBA 46VL748R TV without proper qualifications and necessary experience can lead to serious negative consequences!






Repair MainBoard
The appearance of MainBoard PE0887 is shown in the figure below:
PE0887
Main features of the TOSHIBA 46VL748R device:
Installed matrix (LED panel) LTA460HJ11 T01.
The matrix control uses the Timing Controller (T-CON) PE0893.
The LED driver V71A00017700 is used to power the backlight LEDs.
The formation of the necessary supply voltages for all nodes of the TOSHIBA 46VL748R TV is carried out by the power supply module V71A00017700, or its analogues.
MainBoard - the main board (motherboard) is a PE0887 module, using ZR30011BGCG chips, and others.
The ENGS7301D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: SAMSUNG
Model: LTA460HJ11
Type: a-Si TFT-LCD, Panel
Diagonal size: 46 inch
Resolution: 1920x1080, FHD
Display Mode: S-PVA, Normally Black, Transmissive
Active Area: 1018.08x572.67 mm
Surface: Glare (Haze 0%), Hard coating (3H)
Brightness: 450 cd / m²
Contrast Ratio: 5000: 1
Display colors: 1.07B (8-bit + Hi-FRC), CIE1931 72%
Response Time: 5.5 (G to G)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: LVDS (4 ch, 10-bit), 92 pins
Voltage: 12.0V

Brand: TOSHIBA, Model: 46VL748.
Shortly from the TV: LCD, LED backlight, 46 ", 1920x1080, 1080p Full HD, there is a satellite tuner, sound: 30W, HDMI: 4, Internet access.
For the 46VL748G model, the official website has firmware (software update) version 17.2.24.12.
The composition uses MainBoard PE0887 V28A001177A1 and an LCD panel (matrix) LTA460HJ11 T01.
Power Supply Unit (PSU) PSLF211402A V71A00017700 Power Supply.
Technical description
TOSHIBA 46VL748 LED TV with LTA460HJ11 LCD, 46 "(117 cm) diagonal size in 16: 9 format. The required screen brightness of 450 cd / m² is provided by LED backlighting. The ratio of maximum brightness to minimum (contrast) is 5000: 1 Dynamic contrast ratio of 7,000,000: 1 is achieved by special control of the LEDs. This model uses lateral illumination from Edge LEDs. The design and technical capabilities of the TV include watching programs and movies in high quality HD at a resolution of 1920x1080 pixels graphic 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 Supported media file formats: MP3, WMA, MPEG4, Xvid, DivX, MKV, JPEG.
The power of the sound system 30 W (3x10 W) provide 3 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 x2, RGB, VGA, HDMI x4, USB, Ethernet (RJ-45). 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.
A digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-S2 standards.
The power consumed by the TV in the operating mode from the network is 122 watts.
Overall dimensions: with stand 1092x730x287 mm, without stand 1092x662x29 mm.
TV Weight: with stand: 25.5 kg, without stand: 21.5 kg.
Attention! The LTA460HJ11 T01 panel of the TOSHIBA 46VL748 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