Technical description and composition of the BBK LEM2995 TV, panel type and applicable modules. The composition of the modules.BBK LED
Model: LEM2995
Chassis / Version: EV59XUS
Panel: SK29M21A 76XR-DSV290-PE
T-CON: V290BJ1-XC01, EEPROM T-Con GT4128 (24C128)
LED driver (backlight): integrated into PSU
Power Supply (PSU): integrated into MainBoard
MainBoard: EV59XUS-Y1-A0
IC MainBoard: CPU: TSUMV29 / 39/59, SPI Flash W25Q32,
Technical Specifications LEM2995
BBK LEM2995
General repair guidelines for TV LCD LED
Repair and diagnostics of any electronic device, in particular BBK LEM2995, it is advisable to start with a careful external examination of internal and external elements. It often happens that visible damage to elements or connections helps determine the direction of the troubleshooting. In some cases, faulty elements can be seen with the naked eye, for example, charred resistors or swollen metal-ceramic capacitors, or electrolytic in rectifier filters. Ring cracks formed in the soldered terminals of transformers or heating elements of the circuit are also frequent sources of many malfunctions with a variety of external manifestations.
If the BBK LEM2995 does not turn on, no control lights on the front panel light up or blink, therefore, there is a very high probability of a power module malfunction. In some cases, only the processor power regulator may be faulty. First of all, it is necessary to replace the swollen capacitors of the rectifier filters, if any. If the mains fuse is broken in the power supply, in most cases a breakdown of the power key (s) is detected, which can be integrated with the PWM controller, or a separate field-effect transistor can be used. The rectifier bridge diodes and the electrolytic capacitor of the mains rectifier filter should also be checked.
It should be remembered that in the practice of repair, usually the power switches in switching power supplies (SMPS) do not fail due to their poor quality and, in such cases, it is necessary to look for the cause that led to a malfunction and provoked a breakdown of the key. Most often, the culprits of the accident are dried electrolytic capacitors or dangling resistors in the primary circuit, or the PWM controller chip itself may be faulty. It is also necessary to check all the semiconductor elements of the stabilization circuit in the primary and secondary circuits.
If the BBK LEM2995 does not have an image, there is sound and the channels switch, there is a possibility of a malfunction in the backlight LED circuit of the SK29M21A 76XR-DSV290-PE panel, or their power converter - LED drivers. Sometimes when you turn on the image appears and disappears immediately. In such cases, it is necessary to check the electrolytic capacitors of the power filter of the LED driver itself, including in the secondary rectifier of the main PSU.
To check the health of the LEDs and contact connections in their power circuit, the panel must be disassembled.
It is impossible to check the LED line for breaks without disassembling the panel with a multimeter or tester. For these purposes, it is necessary to open all series-connected PN junctions and a voltage of the order of tens of volts will be required, and ideally, a current source.
Diagnosis and repair of the EV59XUS-Y1-AO motherboard 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.
Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU: TSUMV29 / 39/59, SPI Flash W25Q32, and replace failed chips with new ones. Some malfunctions may be due to the use of BGA soldering technologies in modern Main Board technologies. Typically, such defects are detected by local heating of the chip.
Attention to users! Self-repair of the BBK LEM2995 TV without the appropriate qualifications and experience can lead to its complete non-repairability!
Service Manual with Schematic Diagram 32 pages on the model: -----------> LEM1993, LED1994, LEM1995, LEM1996, LEM1997, LEM2293F, LED2294F, LEM2295F, LEM2296F, LEM2297F, LEM2493F, LED2494F, LEM2495F, LEM2496F, LEM2497F, LEM2993, LED2994, LEM2995, LEM2996, LEM2997, LED2253FW, LED1952DTG, LED2252FDTG, LED2452FDTG, LED2278F
FIRMWARE FOR SPI FLASH -----------> BBK LEM2995, Main: EV59XUS-Y1-AO, Panel: SK29M21A 76XR-DSV290-PE
The appearance of the MainBoard EV59XUS-Y1-A0 is shown in the figure below:EV59XUS-Y1-A0
Main features of the BBK LEM2995 device:
Installed matrix (LED panel) SK29M21A 76XR-DSV290-PE.
The matrix control uses the Timing Controller (T-CON) V290BJ1-XC01.
To power the backlight LEDs, a converter is used, combined with a power supply.
The power module is combined with the MainBoard and is made according to the flyback AC / DC voltage converter circuit.
MainBoard - the main board (motherboard) is an EV59XUS-Y1-A0 module, using CPU chips: TSUMV29 / 39/59, SPI Flash W25Q32, and others.
BBK LEM2995 LED TV with SK29M21A LCD, 29 "(74 cm) diagonal, 16: 9 format. The required screen brightness of 250 cd / m² is provided by LED backlighting. The ratio of maximum brightness to minimum (contrast) is 3000: 1 This model uses side illumination from Edge LEDs. You can view images in high quality HD at a resolution of 1366x768 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. Digital signal processing and generation takes place in the standards 480i, 480p, 576i, 576p, 720p, 1080i Supported multimedia file formats: MP3, WMA, MPEG4, MKV, JPEG. Stereo sound is realized by two built-in 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, VGA, HDMI x3, 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, 1280x1024, 1360x768.
Overall dimensions: With a support of 670x443x175 mm, Without a support of 670x406x53 mm.
Attention! The SK29M21A 76XR-DSV290-PE panel of the BBK LEM2995 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.