Thursday 19 March 2020

REPAIR / SERVICING TV BBK LD1516K

Technical description and composition of the BBK LD1516K TV, panel type and applicable modules. The composition of the modules.
BBK
Model: LD1516K
Panel: SVA156WX1-01TB
Inverter (backlight): Inverter_CCFL_2lamp
Power Supply (PSU): adapter AK083 12v 4,5a
MainBoard: 21901-2
IC MainBoard: CPU: MST718BE-LF, SPI: Pm25LV020, Sound Processor: STV8317F, EEPROM: 24C32, EEPROM: 24C16
Tuner: JS-6H2 / L121
Control: LT121
Technical Specifications LD1516K
BBK LD1516K
General recommendations for repairing TV LCD
Possible malfunctions
- The BBK LD1516K TV does not turn on, does not respond to the remote control and the control panel buttons, the indicators do not light or flash.
Most likely in this case, the main switching power supply (UPS) adapter is faulty.
The owner of a TV can purchase an external power adapter such as adapter and repairing it is not always advisable. In any case, the simplest typical defects characteristic of most IIP schemes can be easily detected and eliminated after opening. It is necessary to measure the secondary output voltages, and in case of their absence, check the serviceability of the power switches of the converters and rectifier diodes for a short circuit.
In case of breakdowns in the secondary circuits, the converter can operate in a short circuit mode, and during short circuit in the elements of the primary circuit, the mains fuse usually breaks.
The breakdown of Mos-Fet keys used in pulsed sources is often caused by malfunctions of other elements, for example, power supply, frequency-setting, damper ... as well as elements of the Negative Stabilization Feedback. The PWM chip can also cause a malfunction of the power switch of the converter and is checked by replacement.
- There is no image, there is sound, it is responding to the remote control. Or immediately after turning on for a second, the image may appear and immediately disappear.
These manifestations can be triggered by a power module, or by defects in the inverter, as well as a distortion of the currents in the lamps due to their uneven wear. After checking all the electrolytic capacitors of the filters that are involved in the power supply of the inverter, it is necessary to ring in its converter the power switches for breakdown and the secondary windings of transformers for an open.
If in diagnosing a malfunction, it is necessary to disable the inverter protection, there is a risk of failure of the power elements of the inverter, and special care is required during work, and after they are finished, it is necessary to restore the protection circuits for further safe operation of the TV by the owner in normal mode.
- 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 21901-2 motherboard should begin by checking the stabilizers and power converters needed to power the microcircuit 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 CPU elements: MST718BE-LF, SPI: Pm25LV020, Sound Processor: STV8317F, EEPROM: 24C32, EEPROM: 24C16 requires the necessary training and professional skills to repair modules at the component level. Problems associated with the use of BGA soldering technologies can sometimes be diagnosed by warming up.
If a JS-6H2 / L121 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 on the corresponding tuner pins.
Attention! Users and owners of LD1516K TVs who do not have the appropriate qualifications, knowledge and experience are strongly advised against self-repair attempts in order to avoid negative consequences that could lead to complete non-repairability of the device.



The appearance of MainBoard 21901-2 is shown in the figure below:
21901-2
21901-2 can be used in TVs:
BBK LD1516K (Panel SVA156WX1-01TB), BBK LD1906SI (Panel SVA190WX02TB), BBK LD2006K (Panel V201V1-T03 Rev.C4).
Main features of the BBK LD1516K device:
Installed matrix (LCD panel) SVA156WX1-01TB.
Inverter_CCFL_2lamp is used to power the backlight.
To power all the internal components of the BBK LD1516K TV, an external adapter type AK083 12v 4,5a is used.
MainBoard - the main board (motherboard) is a 21901-2 module using CPU chips: MST718BE-LF, SPI: Pm25LV020, Sound Processor: STV8317F, EEPROM: 24C32, EEPROM: 24C16 and others.
The tuner JS-6H2 / L121 provides the reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: SVA-NEC
Model: SVA156WX1-01TB
Type: a-Si TFT-LCD, Panel
Diagonal size: 15.6 inch
Resolution: 1366x768, WXGA
Display Mode: TN, Normally White, Transmissive
Active Area: 344.232x193.536 mm
Brightness: 250 cd / m²
Contrast Ratio: 500: 1
Display Colors: 16.7M (6-bit + Hi-FRC), CIE1931 60%
Response Time: 2/6 (Tr / Td)
Frequency: 60Hz
Lamp Type: 2 pcs CCFL Without Driver
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 5.0V


BBK LD1516K LCD TV with SVA156WX1-01TB LCD, 15 "diagonal size, 16: 9 format. 250 cd / m² screen brightness is provided by CCFL (EEFL) fluorescent lamps. The ratio of maximum brightness to minimum (contrast) is 500: 1. It is possible to view images in high quality HD at a resolution of 1366x768 pixels in the standard for graphic decomposition 720p (HD Ready). The input high-frequency or video signal can be processed in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation takes place in the standards 480i, 480p, 576i, 576p, 720p, 1080i Supported media file formats: MP3, WMA, MPEG4, VideoCD, SVCD, Picture CD, JPEG.
The power of the sound system 6 W (2x3 W) provide two speakers. The audio processing system NICAM STEREO is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x2, component, SCART, RGB, VGA, USB. 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, 1360x768.
The power consumed by the TV in the operating mode from the network is 54 watts.
Overall dimensions: 435x350x175 mm.
TV Weight: 6.5 kg.
Attention! The BBA LD1516K LCD TV panel SVA156WX1-01TB is its most expensive component.
Avoid hitting the glass and exerting pressure on the screen to avoid permanent damage to the LCD panel!