Technical description and composition of the SKYLINE 22LT5900 TV, panel type and modules used. The composition of the modules.SKYLINE LED
Model: 22LT5900
Chassis / Version: LDD.M3663.A36
Panel: ST2151B01-1
T-CON: ST2151B01-1-XC-3
LED driver (backlight): integrated into MainBoard
PWM LED driver: SO-8
MOSFET LED driver: TO-252
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MOSFET Power: TO-252
MainBoard: LDD.M3663.A36
IC MainBoard: SPI Flash: 25Q64, Audio: YD1517P
Tuner: DVB-T2 & SAT
Specifications 22LT5900
SKYLINE 22LT5900
General recommendations for TV LCD LED repair
Possible manifestations of defects
- SKYLINE 22LT5900 does not turn on, indicators on the front panel do not light or flash. The TV does not respond to control buttons and the remote control.
In such cases, the AC / DC converter of the mains voltage, which is combined with the main board LDD.M3663.A36, is often faulty. It is necessary to measure its output voltages, and if they are absent (full or partial), the serviceability of the power switches (TO-252) of the converters and rectifier diodes should be checked for a possible short circuit.
In case of any breakdowns of semiconductors in the secondary circuits, the converter can usually operate normally in an emergency short circuit mode. There are no output voltages. And with a short circuit in the power elements of the primary circuit, as a rule, the mains fuse breaks and, less often, the current sensor in the source of the key.
Breakdown of power switches (MosFet) in switching sources is sometimes caused by malfunctions of other circuit elements, for example, in the circuits supplying the PWM controller, frequency setting or damper, as well as in the circuits of Negative Feedback (OOS) stabilization. PWM regulators (PWM) PWM SOT23-6, if they have no visible damage to the case and an open short circuit between the pins, are usually checked by replacing.
- There is no picture, but there is sound and all other functions work. Sometimes, when turned on, the image appears and disappears for a second.
The malfunction in most of these cases is found in the nodes and elements of the LED panel backlighting. The reason can sometimes be in the power supply of the LEDs, but more often in their malfunction (breakdown or open circuit), sometimes in the violation of the contact connections of the LED strips.
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 a voltage of several tens of volts is required to open their junctions. Ideally, a current source is suitable for such purposes. You can open the panel and check each LED separately. Usually, Chinese multimeters lightly light up one 3-volt LED if you connect the probes to it in the forward direction (red probe to the anode, black to the cathode). For dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of LED health. In the event of a malfunction of the LED, its zener diode will either be cut off or broken into the K / Z.
- The TV does not go into operation, does not respond to the remote control. The indicator on the front panel is on or blinking.
Repair or diagnostics of the LDD.M3663.A36 motherboard should begin with checking the stabilizers and power converters required to power the microcircuits and matrix. If necessary, you should update or replace the software (software). In cases of attempts to repair the MB (SSB) board, it is necessary to check the serviceability of its elements - SPI Flash: 25Q64, Audio: YD1517P 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 pins with the board (indicated by warming up).
If there is no reception of TV channels, but the TV is working properly from external devices, first of all, you need to check the supply voltage of the DVB-T2 & SAT tuner and update the software. I2C communication pulses must be monitored with an oscilloscope.
We remind users again! Attempts to repair the SKYLINE 22LT5900 TV yourself without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
Additional MainBoard RepairThe appearance of MainBoard LDD.M3663.A36 is shown in the figure below:
LDD.M3663.A36
The main features of the SKYLINE 22LT5900 device:
Installed matrix (LED panel) ST2151B01-1.
Matrix control uses Timing Controller (T-CON) ST2151B01-1-XC-3.
To power the backlight LEDs, a converter combined with the LDD.M3663.A36 main board is used, controlled by the SO-8 PWM controller. TO-252 switches are used as power elements of the LED driver.
The power module is combined with the MainBoard and is made according to the AC / DC flyback voltage converter using PWM SOT23-6 microcircuits and TO-252 power switches.
MainBoard - the main board (motherboard) is an LDD.M3663.A36 module, using SPI Flash: 25Q64, Audio: YD1517P and others.
The DVB-T2 & SAT tuner provides reception of television programs and tuning to channels.
TV SKYLINE 22LT5900 with LCD display ST2151B01-1, diagonal size 22 "(56 cm) 16: 9 format. The required screen brightness of 180 cd / m² is provided by LED backlighting. Dynamic contrast ratio of 50,000: 1 is achieved by special control of LED operation. The LCD-panel of the TV is implemented with direct backlighting with LED back-mounted - Direct LED.
There is a convenient function of recording TV programs on a USB-drive with subsequent viewing at another time (TimeShift).
LCD panel ST2151B01-1 and software of the main board LDD.M3663.A36 provide viewing of broadcasts and movies in high quality HD at a resolution of 1920x1080 pixels in graphics resolution in 1080p (Full HD). Supported media file formats: MP3, MPEG4, Xvid, DivX, MKV, JPEG.
The power of the acoustic system is 6 W (2x3 W). The NICAM STEREO audio processing system is used.
An external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, VGA, HDMI 1.4, USB.
The digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
The power consumed by the TV operating in mains mode is 36 W.
Dimensions: with stand 510x341x165 mm, without stand 510x307x78 mm.
TV weight: with stand: 2.3 kg, without stand: 1.8 kg.
Attention! The ST2151B01-1 panel of the SKYLINE 22LT5900 LED TV is an expensive and unreliable element.
Do not allow any impacts on the glass and pressure on the screen surface to avoid damage to the LED panel!
It is also unsafe for liquid to spill onto the screen. Sometimes one drop is enough if it drips down the glass onto the cables to make the TV non-repairable.
