Technical description and composition of the HARPER 20R575T TV, panel type and modules used. The composition of the modules.HARPER LED
Model: 20R575T
Chassis / Version: HK.T.RT2957P65
Panel: T195XVN01.0 // KM0195LDAH0027
LED backlight: SJ.HZ.D1950401-2835BS-M 1.14.MD195004
LED driver (backlight): integrated into MainBoard
PWM LED driver: 8 pin
MOSFET LED driver: TO-252
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MOSFET Power: TO-252
MainBoard: HK-T.RT2957P65
IC MainBoard: CPU RT2957P65, Flash 25Q64BV
Tuner: TDA18275
Specifications 20R575T
HARPER 20R575T
General recommendations for TV LCD LED repair
Possible manifestations of defects
- HARPER 20R575T 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.
A malfunction in such cases should be looked for primarily in the circuit of a switching power supply (SMPS) - a converter (AC / DC) of the mains voltage, which is combined with the MainBoard HK-T.RT2957P65 in this model. It is necessary to measure the output voltages in its secondary circuits, and if they are completely absent, the serviceability of the power switches (TO-252) and rectifier diodes should be checked for a possible breakdown (short circuit).
In case of breakdowns of semiconductors in the secondary circuits of any converter, as a rule, it can operate in an emergency mode of short circuit without output voltages, and with a short circuit in the elements of the primary circuit, the mains fuse most often breaks off immediately and, less often, the current sensor in the source of the key.
Mos-Fet power switches used in switching power supplies sometimes fail due to a malfunction of any other elements that can disable it in the key mode, or create an excess of the maximum permissible key parameters. These can be elements supplying a PWM regulator, frequency setting or damper circuits, or elements of negative feedback in the stabilization circuit. PWM controllers PWM SOT23-6, in the absence of visible damage or outright short circuits between the terminals, are checked by replacing them with new ones, or knowingly working properly.
- There is no picture, but there is sound and all other TV functions are working. The image sometimes appears for a second immediately after switching on and disappears.
As a rule, in such cases there is no display backlight. Usually the cause of the malfunction is in the breakage of the LEDs, or in the connectors of the LED strips, but sometimes the LED driver is also faulty.
Without a special current source, it is impossible to check the line of LEDs connected in series, and it is unsafe for them to use any voltage sources above 12V for this purpose. Then all that remains is to open the panel and check each LED separately. Typically, Chinese multimeters with a 9V power supply lightly light up one 3-volt LED, if you connect the probes to it in the forward direction, the red probe to the anode, the black one 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 turn on, does not respond to the remote control. The indicator blinks or signals the standby mode.
Repair or diagnostics of the HK-T.RT2957P65 motherboard should begin with checking the stabilizers and power converters necessary to power the microcircuits and matrix. If necessary, you should update or replace the software (software). Often the MB (SSB) board needs to be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU RT2957P65, Flash 25Q64BV and replace the failed chips with new ones. Some malfunctions may be associated with the use of BGA soldering technologies in modern Main Board. Typically, such defects are detected by local heating of the chip.
If you suspect a malfunction of the TDA18275 tuner, first of all, you need to make sure the software is correct, as well as the presence of the required supply voltage levels and pulses of data exchange with the processor via the I2C bus at the corresponding tuner pins.
Users and owners of TVs should remember that attempts to self-repair the HARPER 20R575T TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!
DOWNLOAD FIRMWARE FOR SPI FLASH -----------> HARPER 20R575T, Main: HK-T.RT2957P65, Panel: KM0195LDAH0027 T195XVN01.0
The appearance of the MainBoard HK-T.RT2957P65 is shown in the figure below:HK-T.RT2957P65
HK-T.RT2957P65 can be used in TVs:
SUPRA STV-LC19T860WL (Panel LC185TT6A), SUPRA STV-LC22T860FL (Panel LC215DTCA).
The main features of the HARPER 20R575T device:
Installed matrix (LED panel) T195XVN01.0 or KM0195LDAH0027.
To power the backlight LEDs, a converter combined with the HK-T.RT2957P65 main board is used, controlled by an 8 pin 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 a HK-T.RT2957P65 module, using CPU RT2957P65, Flash 25Q64BV and others.
The TDA18275 tuner provides reception of television programs and tuning to channels.
HARPER 20R575T TV with LCD T195XVN01.0, 19.6 "(50 cm) diagonal, 16: 9 format. The required screen brightness of 180 cd / m² is provided by LED backlighting. Dynamic contrast ratio of 40,000: 1 is achieved by special LED control. screen manufacturing technology of this TV model is realized with LED backlighting.It is possible to view images in high quality HD at a resolution of 1366x768 pixels in the standard of graphic decomposition 720p (HD Ready ).Supported multimedia file formats: MP3, MPEG4, JPEG.
The power of the sound system of 6 W (2x3 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
External interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x2, component, VGA, HDMI, USB. A headphone output is provided.
The digital tuner is capable of receiving TV 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 458x303x153 mm, without stand 458x268x66 mm.
TV weight: 1.7 kg.
Attention! HARPER 20R575T LED TV panel T195XVN01.0 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.