Technical description and composition of the DEXP F42C7000E TV, type of panel and applicable modules. The composition of the modules.DEXP LED
Model: F42C7000E
Chassis / Version: CV512H-Q42
Panel: CX420DLEDM
LED backlight: CX42D10-ZC21FG-03 2016-09-09 10S1P 303CX420035
T-CON: V420HJ2-P01
LED driver (backlight): integrated into MainBoard
PWM LED driver: BIT3267
MOSFET LED driver: ME15N10-G
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6 AP3125
MOSFET Power: SMK0760F 7A / 600V TO-220F
Mainboard: CV512H-Q42
IC MainBoard: CPU: S2T512, SPI FLASH: GD25Q64, Audio: RT9108NB
Tuner: CDT-9NT372-RD60
Control: IR: 200-GJR-LE32190-OW
Appearance
DEXP F42C7000E
General repair guidelines for TV LCD LED
Possible malfunctions
- The DEXP F42C7000E TV does not turn on and does not show any signs of operability at all. There is no reaction to the remote control and control buttons from the front panel.
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 CV512H-Q42 main board. It is necessary to measure its output voltages, and in case of their absence (full or partial), it is necessary to check the serviceability of the power switches of the converters and rectifier diodes for the presence of a possible short circuit.
In case of breakdowns of semiconductors in secondary circuits, the converter can usually operate abnormally in short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse 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, 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.
Usually in such cases, a malfunction is detected in the backlight nodes of the LED panel. 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 turn on, the indicator indicates standby or operating mode, or blinks.
Repair or diagnostics of the CV512H-Q42 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).
If the TV works normally from external devices, but does not tune to television channels, the CDT-9NT372-RD60 tuner may be malfunctioning. In such cases, first of all, you should make sure that there are supply voltages at its corresponding conclusions. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus. Sometimes the cause of the inoperability of the tuner may be a software failure.
TV users and owners need to remember that attempts to self-repair a DEXP F42C7000E TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!
The appearance of the MainBoard CV512H-Q42 is shown in the figure below:Cultraview CV512H-Q42
Main features of the DEXP F42C7000E device:
Installed matrix (LED-panel) CX420DLEDM.
The matrix control uses the Timing Controller (T-CON) V420HJ2-P01.
To power the backlight LEDs, a converter is used, combined with the main board CV512H-Q42, controlled by the BIT3267 PWM controller. As power elements of the LED driver, keys of the type ME15N10-G 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 AP3125 microchips and power switches of the SMK0760F 7A / 600V TO-220F type.
MainBoard - the main board (motherboard) is a CV512H-Q42 module, using CPU chips: S2T512, SPI FLASH: GD25Q64, Audio: RT9108NB and others.
The tuner CDT-9NT372-RD60 provides the reception of television programs and tuning to channels.