Technical description and composition of the TCL L55P2US TV, panel type and applicable modules. The composition of the modules.TCL LED
Model: L55P2US
Chassis / Version: MS68AD
Panel: LVU550CSOT E9 V1
LED driver (backlight): integrated into PSU
PWM LED driver: GB98ADN
MOSFET LED driver: TO-252
Power Supply (PSU): SHG5804A-101H
MOSFET Power: TO-220
MainBoard: 40-MS68AD-MAC2HG
IC MainBoard: CPU: MS6488, EMMC: 16GB, NAND: 4Gb, AUDIO: TAS5707
Tuner: MXL661 & ATBM7812B
Technical Specifications L55P2US
TCL L55P2US
General repair guidelines for TV LCD LED
Possible malfunctions
- The TCL L55P2US TV does not turn on at all. The control lights do not light or flash. The TV on the remote control and the control panel buttons do not respond.
With such manifestations, the SHG5804A-101H power module usually fails. It is necessary to measure its secondary output voltages, and in case of their absence, check the power switches (TO-220) and rectifier diodes in the converters for a short circuit.
In case of breakdowns in the secondary circuits, the converter can operate in a short circuit mode, and during short circuit in the 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 microcircuits are usually checked by replacement with new ones, or obviously working.
- There is no image, there is sound, all other functions of the TV work. When turned on, the image may sometimes appear for a second.
In such cases, the most likely malfunction of the LED backlight elements. The reason can be found in the malfunction of the LEDs, in the violation of the contact connections of the LED strips, or in the provision of their power (LED driver).
It is impossible to detect a break in the LED line without disassembling the panel with a simple multimeter. The LEDs are connected in series and to open their transitions, a voltage of several tens of volts is required. Ideally, a current source is suitable for such purposes. You can open the panel and check each LED separately. Typically, Chinese multimeters light up a single 3-volt LED, if you connect the probes in the forward direction to it (red probe to the anode, black to the cathode). In dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as a health indicator. 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, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the 40-MS68AD-MAC2HG 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). Board repair and chip replacement AUDIO: TAS5707 are made with the necessary equipment, and the corresponding element base. Faults associated with the application of BGA processor soldering technologies can be localized by the heating method.
Before changing the tuner MXL661 & ATBM7812B, if it is not possible to tune to television channels, make sure that there are supply voltages that need to be measured on 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
Once again, we remind TV users: you should not make attempts to repair it yourself without the appropriate knowledge, experience and the necessary qualifications! Entrust repair to professionals with sufficient experience in the field of repair of electronic equipment.
Service manual / schematic diagram ------------------> Chassis MS68AD MainBoard 40-MS68AD-MAC2HG.rar
The appearance of the MainBoard 40-MS68AD-MAC2HG is shown in the figure below:40-MS68AD-MAC2HG
The appearance of the power supply
Main features of the TCL L55P2US device:
Installed matrix (LED-panel) LVU550CSOT E9 V1.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by a GB98ADN PWM controller. As power elements of the LED driver, keys of the TO-252 type are used.
The necessary supply voltages for all nodes of the TCL L55P2US TV are generated by the SHG5804A-101H power module, or its analogs using TO-220 type power switches.
MainBoard - the main board (motherboard) is a 40-MS68AD-MAC2HG module, using CPU chips: MS6488, EMMC: 16GB, NAND: 4Gb, AUDIO: TAS5707 and others.
The MXL661 & ATBM7812B tuner provides TV reception and channel tuning.
TCL L55P2US TV with LVU550CSOT LCD display, diagonal size 55 "(140 cm) in 16: 9 format. LED TV backlighting is implemented in the technology for making this TV model. You can watch movies in the highest possible quality UHD at a resolution of 3840x2160 pixels in 4K standard UHD.
The L55P2US 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. Supported media file formats: MP3, MPEG4, MKV, JPEG.
The power of the sound speaker system 16 W (2x8 W) is provided by 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, component, VGA, HDMI x3, USB, Ethernet (RJ-45), Wi-Fi. 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.
Overall dimensions: with stand 1243x779x215 mm, without stand 1243x720x63 mm.
TV Weight: with stand: 14 kg, without stand: 13.6 kg.
Attention! The panel of the LVU550CSOT E9 V1 LED-TV TCL L55P2US 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.
