Technical description and composition of the DEXP H32B7400C TV, panel type and applicable modules. The composition of the modules.DEXP LED
Model: H32B7400C
Chassis / Version: JUC7.820.00117550
Panel: C320X14-E3-H (G7)
LED backlight: SVJ320AJ9_Rev00_6LED_140707 LB-M320X13-E1-A-G1-SE2
T-CON: MT3151A05-5-XC-5 ST3151A05-8 Ver2.1
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP4012
MOSFET LED driver: MDD14N25
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MainBoard: JUC7.820.00117550 HL T57EJ T1-19
IC MainBoard: CPU: 9206B, SPI Flash: GD25Q64, MP1471AGJ, TPS54428, RT9108NB
Tuner: CH DMI21-C816RH
Technical Specifications H32B7400C
DEXP H32B7400C
General repair guidelines for TV LCD LED
Possible malfunctions
- The DEXP H32B7400C TV does not turn on, does not respond to the remote control and buttons on the control panel, does not light up or blink indicators.
In such cases, the main power source, the AC / DC voltage converter, which is combined with the MainBoard JUC7.820.00117550, may turn out to be faulty. 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 the event of breakdowns in the secondary circuits of the converter, it can usually fail in short circuit mode, and in the event of a short circuit in the power elements of the primary circuit, the mains fuse or current sensor at the source of the key most often breaks.
The breakdown of Mos-Fet keys used in pulsed sources is often caused by malfunctions of other elements, for example, in the power supply circuit of a PWM controller, in frequency-setting or damping circuits, as well as in Negative Stabilization Feedback. PWM SOT23-6 PWM chips are usually checked by replacing with new ones, or obviously working.
- There is no image, but there is sound and reaction to the remote control. Or for a second, the image may appear immediately after switching on.
As a rule, in such cases there is no display backlight. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To check the health in the LED circuit, it is better to use a current source with a maximum voltage of 200V. We do not recommend using any voltage sources for this purpose. You can check each LED individually with a simple Chinese multimeter (powered by 9 volts) in the P-N-junction test mode. If you connect the red probe of the multimeter to the anode of the LED, and the black to its cathode, then the 3-volt LED will light up slightly, and in the opposite direction you can detect the transition of the emergency zener diode. A zener diode PN junction indirectly indicates a LED-a
- 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 JUC7.820.00117550 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 (SSB) board, it is necessary to check the health of its elements - CPU: 9206B, SPI Flash: GD25Q64, MP1471AGJ, TPS54428, RT9108NB 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).
A malfunction of the tuner CH DMI21-C816RH is established after checking the software and all supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
Attention to users! Self-repair of a DEXP H32B7400C TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
The appearance of the MainBoard JUC7.820.00117550 is shown in the figure below:JUC7.820.00117550
JUC7.820.00117550 can be used in TVs:
BBK 32LEM-1018/T2C (Panel C320X14-E12-H), DEXP H32B7200C (Panel C320X14-E12-H(G3)), DEXP H32B7400C (Panel C320X14-E3-H (G7)), ERISSON 32LEC2500 (Panel M320X13-E2-B), TELEFUNKEN LED32S22T2 (Panel M320X13-E1-A).
Main features of the DEXP H32B7400C device:
Installed matrix (LED-panel) C320X14-E3-H (G7).
The matrix control uses the Timing Controller (T-CON) MT3151A05-5-XC-5.
To power the backlight LEDs, a converter is used, combined with the main board JUC7.820.00117550, controlled by the MP4012 PWM controller. As power elements of the LED driver, keys of the MDD14N25 type are used.
The power module is combined with the MainBoard and is made according to the flyback AC / DC voltage converter circuit using PWM SOT23-6 microcircuits.
MainBoard - the main board (motherboard) is a JUC7.820.00117550 module, using CPU chips: 9206B, SPI Flash: GD25Q64, MP1471AGJ, TPS54428, RT9108NB and others.
The CH DMI21-C816RH tuner provides TV reception and channel tuning.
DEXP H32B7400C TV with C320X14-E3-H LCD, 32 "(81 cm) diagonal size in 16: 9 format. The required screen brightness of 250 cd / m² is provided by LED backlighting. Contrast - the ratio of maximum brightness to minimum is 3000: 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 . Analog PAL, SECAM, NTSC systems Image processing and the formation of the digital signal is in 480i standards, 480p, 576i, 576p, 720p Supported multimedia file formats:. MP3, MPEG4, DivX, MKV, JPEG.
The power of the sound system 10 W (2x5 W) provides 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, component, 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, 1360x768. The digital tuner is capable of receiving television channels in DVB-T MPEG4, DVB-C, DVB-T2 standards.
Overall dimensions: with stand 735x488x220 mm, without stand 735x439x88 mm.
TV Weight: with stand: 5.3 kg, without stand: 4.9 kg.
Attention! The C320X14-E3-H (G7) panel of a DEXP H32B7400C 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.
