Saturday 18 April 2020

REPAIR / SERVICING TV DEXP F32D7000C

Technical description and composition of the DEXP F32D7000C TV, panel type and applicable modules. The composition of the modules.
DEXP LED
Model: F32D7000C
Chassis / Version: JUC7.820.00188290
Panel: ST3151B01-1 C320F18-E1-H
LED backlight: RF-BS320S30-0401S-29
T-CON: ST3151B01-1-XC-2
LED driver (backlight): integrated into MainBoard
PWM LED driver: SOT23-6
MOSFET LED driver: TO-252
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MOSFET Power: 70R900P
MainBoard: JUC7.820.00188290
IC MainBoard: SPI Flash: GD24Q64
Tuner: ST18WM-2K-E
Technical Specifications F32D7000C
DEXP F32D7000C
General repair guidelines for TV LCD LED
Possible malfunctions
- The DEXP F32D7000C TV does not turn on, does not respond to the remote control and the control panel buttons, the indicators do not light or flash.
First of all, in such cases, you should verify the operability of the common switching power supply (IIP) - AC / DC voltage converter of the mains voltage. All source elements in this TV model are located on the MainBoard JUC7.820.00188290 main board. Then it is necessary to measure its output voltages and, in case of their complete or partial absence, it is necessary to check the serviceability of power switches (70R900P) and rectifier diodes of converters for possible 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.
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, 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.
In such cases, the most likely malfunction of the LED backlight elements. The reason can be both in the power supply of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
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 JUC7.820.00188290 motherboard should begin by checking the stabilizers and power converters needed to power the microcircuit and matrix. If necessary, update or replace the software (software). Complex repair of MB (SSB) is possible only in the conditions of a service center with the necessary equipment. Checking or replacing elements of SPI Flash: GD24Q64 requires the necessary training and professional skills to repair modules at the component level. Problems associated with the use of BGA soldering technologies can sometimes be diagnosed by warming up.
Before replacing the ST18WM-2K-E tuner, if there is no channel tuning, you must first check the software and the supply voltage at its terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus
Attention! For users and owners of F32D7000C TVs who do not have the appropriate qualifications, knowledge and experience, we strongly recommend against attempting self-repair in order to avoid negative consequences that could lead to complete non-repairability of the device.


FIRMWARE FOR SPI FLASH  ----------->   DEXP F32D7000C, Main: JUC7.820.00188290, Panel: ST3151B01-1

SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    MainBoard JUC7.820.00188290


 The appearance of the MainBoard JUC7.820.00188290 is shown in the figure below:
JUC7.820.00188290
Main features of the DEXP F32D7000C device:
Installed matrix (LED panel) ST3151B01-1 C320F18-E1-H.
The matrix control uses the Timing Controller (T-CON) ST3151B01-1-XC-2.
To power the backlight LEDs, a converter is used, combined with the main board JUC7.820.00188290, controlled by the SOT23-6 PWM controller. As power elements of the LED driver, keys of the TO-252 type are used.
The power module is combined with the MainBoard and is made according to the scheme of a flyback AC / DC voltage converter using PWM SOT23-6 microcircuits and power switches of the type 70R900P.
MainBoard - the main board (motherboard) is a JUC7.820.00188290 module, using SPI Flash chips: GD24Q64 and others.
The ST18WM-2K-E tuner provides television reception and channel tuning.
A DEXP F32D7000C TV with an ST3151B01-1 LCD display, 32 "(81 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 3000: 1. The LCD panel uses direct LED backlighting - Direct LED, which allows TVs and movies to be viewed in high quality HD at a resolution of 1920x1080 pixels in graphic resolution according to the 1080p standard (Full HD). Supported file formats for mult Media: MP3, WMA, MPEG4, MKV.
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, VGA, HDMI x3, 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 working in the network mode is 45 watts.
Overall dimensions: with stand 735x467x218 mm, without stand 735x434x69 mm.
TV Weight: with stand: 4.2 kg, without stand: 4.1 kg.
Attention! The ST3151B01-1 panel of a DEXP F32D7000C 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.