DEXP LEDModel: 50A8000
Panel: T500HVN08.3 HE500HFD-B62 / S5 / GM
LED backlight: LT-1134017-A HE500HF-B57 RSAG7.820.5815
T-CON: T500HVN08.3 50T20-C06
LED driver (backlight): integrated into PSU
Power Supply (PSU): HLL-4855WA RSAG7.820.5687 / ROH
PWM Power: NCP1271, NCP1608
MOSFET Power: 10N60, 8N65
MainBoard: RSAG7.820.5872 / ROH
Tuner: RE221ZN
Specifications 50A8000
DEXP 50A8000
General repair guidelines for TV LCD LED
Possible malfunctions
- The DEXP 50A8000 TV does not turn on and does not show any signs of operability at all. There is no reaction to either the remote control or the front panel control buttons.
With such manifestations, a malfunction is most likely to be detected in the HLL-4855WA power supply module. It is then necessary to measure its output voltages and, if they are absent, it is necessary to check the power switches and rectifier diodes of the converters for a short-circuit probability.
In the event of breakdowns in the secondary circuits, the converter may emergencyly operate in the short circuit mode, and in the event of a 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. It can be supply, damper circuits, or elements of OOS (negative feedback) stabilization. The reason for the breakdown of the power switch may be PWM (PWM). It is checked only by replacement with a known good one.
- There is no image, there is sound, it responds to the remote control. Or the image may appear for a second when turned on and immediately disappears.
The most likely in these cases is a malfunction of the LED backlight. 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.
It is impossible to check the line of series-connected LEDs without a special current source, and for this purpose it is not safe to use any voltage sources above 12V for them. Then it remains only to open the panel and check each LED separately. Usually, Chinese 9V-powered multimeters light up a single 3-volt LED, if you connect the probes in the forward direction, the red probe to the anode, and the black to the cathode. In dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of health. In the event of a LED malfunction, its zener diode will either be cut off or broken into short-circuit.
- The TV does not turn on, the indicator indicates standby or operating mode, or blinks.
Repair or diagnostics of the RSAG7.820.5872 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).
Before changing the tuner RE221ZN, if there is no possibility of tuning to television channels, you should make sure that there are supply voltages that must be measured at the corresponding terminals of the tuner and check the software for correctness. The pulses of the data exchange of the tuner with the processor can be controlled by an oscilloscope
Attention TV owners! Attempts at self-repair of the DEXP 50A8000 are not recommended by the manufacturer and can lead to serious negative consequences!
The appearance of the MainBoard RSAG7.820.5872 is shown in the figure below:RSAG7.820.5872
The appearance of the power supply
Main features of the DEXP 50A8000 device:
Installed matrix (LED panel) T500HVN08.3 HE500HFD-B62 / S5 / GM.
The matrix control uses the Timing Controller (T-CON) T500HVN08.3.
To power the backlight LEDs, a converter is used, combined with a power supply.
The necessary supply voltages for all nodes of the DEXP 50A8000 TV are generated by the HLL-4855WA power supply module or its analogs using NCP1271, NCP1608 microcircuits and 10N60, 8N65 type power switches.
MainBoard - the main board (motherboard) is an RSAG7.820.5872 module.
The RE221ZN tuner provides television reception and channel tuning.
DEXP 50A8000 TV with T500HVN08.3 LCD, 50 "(127 cm) diagonal size in 16: 9 format. The required screen brightness of 330 cd / m² is provided by LED backlighting. Contrast - the ratio of maximum brightness to minimum is 3000: 1. In this model, a panel with the end position of the backlight LEDs is used - Edge LED.
There is support for 3D images, without glasses, converting 2D to 3D. TV features include watching programs and movies in high quality HD at a resolution of 1920x1080 pixels in a graphical decomposition standard 1080p (Full HD).
The 50A8000 is equipped with SMART software, integrated applications and the ability to work on the Internet. Connecting to the Internet can be done via Wi-Fi. The input high-frequency or video signal is decoded in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation occurs in standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Supported media file formats: MP3, WMA, MPEG4, DivX, MKV, JPEG.
The power of the speaker system of sound 8 W (2x4 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, VGA, HDMI x4, USB x3, Ethernet (RJ-45), Wi-Fi. 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, 1024x768, 1280x1024, 1360x768, 1920x1080. A digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Overall dimensions: with stand 1116x690x226 mm, without stand 1116x645x60 mm.
TV Weight: with stand: 16.5 kg, without stand: 16 kg.
Attention! The T500HVN08.3 HE500HFD-B62 / S5 / GM panel of the DEXP 50A8000 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.