Friday 20 March 2020

REPAIR / SERVICING TV BBK LT1526S

Technical description and composition of the BBK LT1526S TV, type of panel and applicable modules. The composition of the modules.
BBK
Model: LT1526S
Chassis / Version: Ver1.0
Panel: N154I2-P02 6047120002
Inverter (backlight): LK-P1150101C
Power Supply (PSU): LK-P1150101C
MainBoard: HDxx7050H HD0911F479 HD_T7050H_V1.3A
IC MainBoard: SPV7050P TDA9886TS, YD1517P, 4558
Control: RC1902
Technical Specifications LT1526S
BBK LT1526S
General recommendations for repairing TV LCD
Possible malfunctions
- BBK LT1526S 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 most of these cases, the LK-P1150101C main switching power supply fails. It is necessary to measure the secondary output supply 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 main fuse usually breaks.
The breakdown of Mos-Fet keys used in pulsed sources is often caused by malfunctions of other elements, for example, power, 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.
The defect can be caused by problems in the nodes or elements of the backlight of the display, or in the power supply of the lamps or the inverter.After checking all the electrolytic capacitors of the filters that are involved in the power supply of the inverter, you must ring in its converter power keys for breakdown and 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 when working, 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 indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the HDxx7050H 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). When repairing an MB board, you need to check its components SPV7050P TDA9886TS, YD1517P, 4558. Faulty elements should be replaced. If chips with BGA soldering technology are used, a problem in its implementation is detected by the local heating of the chip.
TV users and owners need to remember that attempts to self-repair a BBK LT1526S TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!

Service Manual with Schematic Diagram (DOC) 29 pages 2009 on model LT1526S, LT2428S.

SCHEMATIC / MANUAL ------------->   LT1526S


Main features of the BBK LT1526S device:
Installed matrix (LCD panel) N154I2-P02 6047120002.
An inverter LK-P1150101C is used to power the backlight.
The formation of the necessary supply voltages for all nodes of the BBK LT1526S TV is carried out by the power module LK-P1150101C, or its analogues.
MainBoard - the main board (motherboard) is an HDxx7050H hd_t7050h module, using chips SPV7050P TDA9886TS, YD1517P, 4558 and others.


 BBK LT1526S LCD TV with CMO LCD, 15 "diagonal 16:10 format. Screen brightness of 150 cd / m² is provided by CCFL (EEFL) fluorescent lamps. The ratio of maximum brightness to minimum (contrast) is 400: 1. It is possible to view images in high quality HD at a resolution of 1280x800 pixels in the standard of 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 occurs in standards 480i, 480p , 576i, 576p, 720p, 1080i.
The power of the sound system 3 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, S-Video, SCART, RGB, VGA, HDMI. 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.
The power consumed by the TV in the operating mode from the network is 35 watts.
Overall dimensions: 529x382x210 mm.
Mass of the TV: 4.3 kg.
Attention! The BBK LT1526S LCD TV panel CMO N154I2-P02 is its most expensive component.
Avoid hitting the glass and exerting pressure on the screen to avoid permanent damage to the LCD panel!