Technical description and composition of the DEXP 28A3000 TV, type of panel and applicable modules. The composition of the modules.DEXP LED
Model: 28A3000
Chassis / Version: JUC7.820.00084054
Panel: R-HS055D-1MF
LED driver (backlight): integrated into PSU
PWM LED driver: MP4012
Power Supply (PSU): R-HS055D-1MF
PWM Power: PWM SOT23-6
MainBoard: JUC7.820.00084054
IC MainBoard: Spi Flash: 25Q64BSIG
Tuner: DT21WN-2A-E
Specifications 28A3000
DEXP 28A3000
General repair guidelines for TV LCD LED
Possible malfunctions
- The DEXP 28A3000 TV does not turn on, does not respond to the remote control and buttons on the control panel, the indicators do not light or flash.
Typically, with such manifestations, the defect is caused by faulty elements in the main power module R-HS055D-1MF. It is necessary to measure the output voltages in its secondary circuits, and if they are completely absent, it is necessary to check the serviceability of power switches and rectifier diodes for possible breakdown (short circuit).
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 power switches, used in switching power supplies, sometimes fail due to a malfunction of any other elements that can put it out of operation in key mode or create an excess of the maximum permissible parameters of the switch. These can be elements supplying the PWM controller, frequency-setting or damping circuits, or negative feedback elements in the stabilization circuit. PWM SOT23-6 PWM controllers, in the absence of visible damage or obvious short-circuit between the terminals, are checked by replacing with new ones, or obviously working.
- There is no image, there is sound, it responds to the remote control, the channels are switched. In some cases, the image appears when you turn on and immediately disappears.
In such cases, the most likely malfunction of the LED backlight elements. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To check the LED strips, to open all the transitions of the LEDs, several tens of volts or more are needed, it is best to use a current source for such purposes. The breakage of several PN junctions connected in series cannot be detected with a multimeter or tester. In such cases, it is necessary to open the panel and check each LED. If your multimeter cannot open the LED transitions in forward bias, you can sometimes detect the presence of a PN junction of the protective zener diode by connecting the probes in the opposite direction. If the zener diode is broken or broken in short-circuit, then the LED is faulty and needs to be replaced.
- 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 JUC7.820.00084054 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). In cases of attempts to repair the MB board (SSB), you need to check the health of its elements - Spi Flash: 25Q64BSIG which may require replacement with new ones. If a BGA processor is installed, there is a possibility of a violation of the soldering of the contacts of its conclusions with the board (it is diagnosed by heating).
The malfunction of the tuner DT21WN-2A-E is established after checking the software and all the supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
For 28A3000 TV owners, we recommend that you contact qualified specialists with the necessary work experience for repairs! Self-repair attempts without the appropriate knowledge and skills can lead to irreversible negative consequences!
FIRMWARE FOR SPI FLASH -----------> DEXP 28A3000, Main: JUC7.820.00084054, Panel: R-HS055D-1MF
The appearance of the MainBoard LS1B is shown in the figure below:LS1B
JUC7.820.00084054 can be used in TVs:
BBK 40LEM-3080/FT2C (Panel ECG390AH-LD2 (SN)), BBK 32LEM-3081/T2C (Panel M320X13-E2-H), BBK 32LEM-1003/T2C (Panel M320X13-E4-L HD), DEXP 28A3000 (Panel R-HS055D-1MF), DEXP 50A7000 (Panel C500F13-E3-A), DNS C28DC2000 (Panel M280X13-E1-H), DNS C39DC2000 (Panel M390F13-E1-A), ERISSON 42LEC2000 (Panel M420F13-E1-L (G1)), ERISSON 55LEC2000 (Panel M550F13-E1-A 1080p Full HD), ERISSON 28LEC2000 (Panel M280X13-E1-H), RUBIN RB-32SD8T2C (Panel M320X13-E3-H), TELEFUNKEN TF-LED32S12T2 (Panel M320X12-E9-A(1)).
The appearance of the power supply
Main features of the DEXP 28A3000 device:
Installed matrix (LED panel) R-HS055D-1MF.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the MP4012 PWM controller.
The necessary supply voltages for all nodes of the DEXP 28A3000 TV are generated by the power module R-HS055D-1MF, or its analogs using PWM SOT23-6 microcircuits.
MainBoard - the main board (motherboard) is a JUC7.820.00084054 module, using Spi Flash chips: 25Q64BSIG and others.
Tuner DT21WN-2A-E provides the reception of television programs and tuning to channels.
DEXP 28A3000 TV with M280X13-E1-H LCD, 28 "(71 cm) diagonal size in 16: 9 format. The required screen brightness of 200 cd / m² is provided by LED backlighting. Contrast - the ratio of maximum brightness to minimum is 4000: 1. The LCD panel uses direct pixel illumination with rear LEDs - Direct LED. You can watch broadcasts and movies and 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 is decoded in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation occurs in the standards 480i, 480p, 576i, 576p, 720p. Supported media file formats: MP3, WMA, MPEG4, DivX, MKV, JPEG.
The power of the acoustic system of sound 20 W (2x10 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 x2, audio x3, component, VGA, HDMI x3, USB. 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. A digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Overall dimensions: with stand 648x440x165 mm, without stand 648x386x85 mm.
TV Weight: with stand: 5.5 kg, without stand: 5 kg.
Attention! The M280X13-E1-H panel of a DEXP 28A3000 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.
