Technical description and composition of the BBK 20LEM-1056 TV, panel type and applicable modules. The composition of the modules.BBK LED
Model: 20LEM-1056 / T2C
Chassis / Version: CV512L-U24
Panel: CX195DLEDM
LED backlight: Edge LED
T-CON: M195XTN01.0 Ctrl BD
LED driver (backlight): integrated into MainBoard
PWM LED driver: BIT3367A
MOSFET LED driver: MMBT3904
Power Supply (PSU): integrated into MainBoard
PWM Power: LD5535
MOSFET Power: 70R900P
MainBoard: CV512L-U24
IC MainBoard: CPU: S2T512, SPI Flash: GD25Q64C, Audio: TDA3118E28
Tuner: CDT-9NT372-RD60 (RDA5160)
Technical Specifications 20LEM-1056 / T2C
BBK 20LEM-1056
General repair guidelines for TV LCD LED
Possible malfunctions
- The BBK 20LEM-1056 TV does not turn on at all. There is no reaction to the remote control and front-panel control buttons. Indicator lights do not light or flash.
The malfunction in such cases should be sought primarily in the circuit of a switching power supply (IIP) - a network voltage converter (AC / DC), which is combined with the MainBoard CV512L-U24 main board in this model. In the absence of the necessary supply voltages in the secondary circuits of the converters, it is necessary to check the power switches (70R900P) and rectifier diodes for a possible partial or complete breakdown.
In case of breakdowns in the secondary circuits, the converter, as a rule, can emergency work in the short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse usually breaks.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements that can put it out of operation in key mode or provoke an excess of the maximum current or voltage. These can be circuits supplying the PWM controller, damping or frequency-setting circuits, or elements of OOS (negative feedback) in the stabilization circuit. PWM controllers (PWM) LD5535, in the absence of external damage and short circuit between the terminals, are checked by replacing with obviously good ones.
- 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.
In most of these cases, a malfunction is detected in the nodes and backlight elements of the LED panel. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
It should be remembered that it is not possible to determine the open circuit in the LED lines without disassembling the panels with a tester or multimeter without an additional device, for example, a current source. To open all PN junctions connected in series at once, a voltage of several tens of volts may be required. Then it is necessary to open the panel and check each LED separately with a multimeter. If the capabilities of your multimeter do not allow you to open the LED in the forward direction or dual LEd are used, then the PN junction of the emergency zener diode can indirectly serve as a health indicator. In case of LED-a failure, the zener diode PN junction 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 CV512L-U24 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 CPU components: S2T512, SPI Flash: GD25Q64C, Audio: TDA3118E28. Defective items 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.
In the absence of tuning to the channels of on-air or cable television, you should make sure that the software is correct, as well as in accordance with the ratings of the supply voltages on the terminals of the tuner CDT-9NT372-RD60 (RDA5160). It is also necessary to check the presence of pulses of data exchange between the tuner and the processor via the I2C bus using an oscilloscope.
TV users and owners need to remember that attempts to self-repair a BBK 20LEM-1056 TV without the appropriate qualifications and necessary experience can lead to serious negative consequences!
FIRMWARE FOR SPI FLASH -----------> BBK 20LEM-1056/T2C, Main: CV512L-U24, Panel: CX195DLEDM.
Service manual / schematic diagram -----------------------> Main CV512L-U24
The appearance of the MainBoard CV512L-U24 is shown in the figure below:
CV512L-U24
Main features of the BBK 20LEM-1056 device:
Installed matrix (LED-panel) CX195DLEDM.
The matrix control uses the Timing Controller (T-CON) M195XTN01.0.
To power the backlight LEDs, a converter is used, combined with the main board CV512L-U24, controlled by the BIT3367A PWM controller. As power elements of the LED driver, keys of the type MMBT3904 are used.
The power module is combined with the MainBoard and is made according to the flyback AC / DC voltage converter using LD5535 microcircuits and power switches of the type 70R900P.
MainBoard - the main board (motherboard) is a CV512L-U24 module, using CPU chips: S2T512, SPI Flash: GD25Q64C, Audio: TDA3118E28 and others.
The tuner CDT-9NT372-RD60 (RDA5160) provides the reception of television programs and tuning to channels.
BBK 20LEM-1056 / T2C LED TV with a CX195DLEDM LCD, 19.6 "(50 cm) diagonal of 16: 9 format. The required screen brightness of 180 cd / m² is provided by LED backlighting. The ratio of maximum brightness to minimum (contrast) is 3000: 1. LED display technology is implemented in the model’s display technology. HD images can be viewed in high resolution at 1366x768 pixels in the standard of graphic decomposition 720p (HD Ready). Supported media file formats: MP3, WMA, MPEG4, DivX, MKV , JPEG.
The power of the sound system 10 W (2x5 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, VGA, HDMI, USB. An output for connecting headphones is provided. 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 36 watts.
Overall dimensions: with stand 464x307x140 mm, without stand 462x273x76 mm.
TV Weight: 1.9 kg.
Attention! The CX195DLEDM panel of the BBK 20LEM-1056 / T2C 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.