Technical description and composition of the GOLDSTAR LT-28T450R TV, panel type and modules used. The composition of the modules.GOLDSTAR LED
Model: LT-28T450R
Chassis / Version: V1R08
Panel: C275X15-E1-H
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP4012
MOSFET LED driver: TO-252
Power Supply (PSU): integrated into MainBoard
PWM Power: NCP1251A (PWM SOT23-6)
MOSFET Power: 70R600P
MainBoard: JUC7.820.00130484
IC MainBoard: CPU: MSMHFK, SPI FLASH: GD25Q32
Tuner: CH DM121 C816RH
LT-28T450R Specifications
GOLDSTAR LT-28T450R
General recommendations for TV LCD LED repair
Possible manifestations of malfunctions
- TV GOLDSTAR LT-28T450R does not turn on at all. Control lamps do not light up or blink. The TV on the remote control and control panel buttons does not respond.
First of all, in such cases, you should make sure that the common switching power supply (SMPS) is working - the AC / DC voltage converter of the mains voltage. All source elements in this TV model are located on the MainBoard JUC7.820.00130484. Then you should measure its output voltages and, in case of their complete or partial absence, it is necessary to check the serviceability of the power switches (70R600P) and rectifier diodes of the converters for a possible short circuit.
In case of diode breakdowns in the secondary circuits, the converter can operate in an emergency mode of short circuit without output voltages, and in the event of a short circuit in the power elements of the primary circuit, the mains fuse and / or the current sensor in the source of the key usually breaks off.
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 controllers (PWM) NCP1251A (PWM SOT23-6), if they have no visible damage to the case and an outright short circuit between the pins, are usually checked by replacing.
- There is no image, there is sound, it reacts to the remote control. Or the image may appear for a second when turned on and disappear immediately.
Usually, in such cases, a malfunction is detected in the LED panel backlight nodes. 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 supply (LED driver).
To test the LED strips, in order 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 junctions in forward bias, you can sometimes detect the presence of a protective zener diode PN junction by connecting the probes in the opposite direction. If the zener diode is cut off or broken in K / Z, then the LED is faulty and needs to be replaced.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals the standby mode.
If the TV operates normally from external devices, but does not tune to TV channels, the CH DM121 C816RH tuner may be faulty. In such cases, first of all, you should make sure that there are supply voltages at its corresponding terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus. Sometimes the reason for the inoperability of the tuner may be a software failure.Repair or diagnostics of the JUC7.820.00130484 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). Repair of the board and replacement of CPU: MSMHFK, SPI FLASH: GD25Q32 microcircuits are made with the necessary equipment and the corresponding element base. Malfunctions associated with the use of BGA soldering technologies can be localized by the warm-up method.
Users and owners of TVs should remember that attempts to self-repair the GOLDSTAR LT-28T450R TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!
DOWNLOAD FIRMWARE FOR SPI FLASH -----------> GOLDSTAR LT-28T450R V1R08, Main: JUC7.820.00130484, Panel: C275X15-E1-H
The appearance of the MainBoard JUC7.820.00130484 is shown in the figure below:JUC7.820.00130484
Main features of the GOLDSTAR LT-28T450R device:
Installed matrix (LED-panel) C275X15-E1-H.
To power the backlight LEDs, a converter combined with the JUC7.820.00130484 main board is used, controlled by the MP4012 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 circuit using NCP1251A microcircuits (PWM SOT23-6) and power switches of the 70R600P type.
MainBoard - the main board (motherboard) is a JUC7.820.00130484 module, using CPU chips: MSMHFK, SPI FLASH: GD25Q32 and others.
Tuner CH DM121 C816RH provides reception of television programs and tuning to channels.
GOLDSTAR LT-28T450R TV with LCD C275X15-E1-H, 28 "(71 cm) diagonal, 16: 9 format. The required screen brightness of 240 cd / m² is provided by LED backlighting. Dynamic contrast ratio of 60,000: 1 is achieved by special control operation of LEDs. The technology of production of the screen of this TV model is implemented LED LED backlight. It is possible to view images in high quality HD at a resolution of 1366x768 pixels in the standard of graphic resolution 720p (HD Ready). Input high-frequency or video signal can be processed in analog systems PAL, SECAM, NTSC Graphic processing and digital signal shaping takes place in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p Supported media file formats: MP3, WMA, MPEG4, MKV, JPEG.
Speaker power 10 W (2x5 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), component, SCART, VGA, HDMI x2, MHL, USB. A headphone output is provided. To connect a computer or laptop to this TV model, a VGA (D-Sub 15) connector on the TV case is used, this interface supports resolutions: 640x480, 800x600, 1024x768, 1360x768.
The digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Dimensions: with stand 650x530x163 mm, without stand 650x470x85 mm.
TV weight: with stand: 3.6 kg, without stand: 3.4 kg.
Attention! Panel C275X15-E1-H of LED TV GOLDSTAR LT-28T450R is an expensive and unreliable element.
Do not allow any impact 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 unrepairable.