Wednesday, 29 April 2020

REPAIR / SERVICING TV MYSTERY MTV-2426LT2

Technical description and composition of the MYSTERY MTV-2426LT2 TV, type of panel and applicable modules. The composition of the modules.
MYSTERY LED
Model: MTV-2426LT2
Chassis / Version: V4P07
Panel: V236BJ1-P03
T-CON: V236BJ1-XC01
LED driver (backlight): integrated into MainBoard
PWM LED driver: OB3350
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MainBoard: MS308C1-ZC01-01
IC MainBoard: CPU: MSD308BEM, SPI Flash: GD25Q64, SOUND: TPA1517
Tuner: TDA18275
Technical Specifications MTV-2426LT2
MYSTERY MTV-2426LT2
General repair guidelines for TV LCD LED
Possible malfunctions
- The MYSTERY MTV-2426LT2 TV does not turn on and does not show any signs of turning on. There are no reactions to the control buttons or the remote control.
In such cases, the common power source, the AC / DC voltage converter, which is combined with the elements of the MS308C1-ZC01-01 main board, is often faulty. It is necessary to measure its secondary output voltages, and in case of their absence, check the operability of the power switch of the converter and rectifier diodes for a possible short circuit.
In the event of a breakdown in the secondary circuits of the converter, it can usually fail in short circuit mode, and in the event of a short circuit in the power elements of the primary circuit, the main fuse or current sensor at the source of the key most often 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 also be PWM SW23-6 PWM. It is checked only by replacement with a known good one.
- There is no image, but there is sound, it reacts to the remote control. Or the image appears when you turn it on and immediately disappears
In most cases, the malfunction is caused by the lack of a backlight display. 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 should be remembered that it is not possible to determine the open circuit in the LED lines without disassembling the panels with a tester or multimeter without an additional device, for example, a current source. To open all PN junctions connected in series at once, a voltage of several tens of volts may be required. Then it is necessary to open the panel and check each LED separately with a multimeter. If the capabilities of your multimeter do not allow you to open the LED in the forward direction or dual LEd are used, then the PN junction of the emergency zener diode can indirectly serve as a health indicator. In case of LED-a failure, the zener diode PN junction will either be cut off or broken into short-circuit.
- The indicator on the front panel blinks, the TV does not turn on in the operating mode, it does not respond to the remote control.
Repair or diagnostics of the motherboard MS308C1-ZC01-01 should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU: MSD308BEM, SPI Flash: GD25Q64, SOUND: TPA1517 and replace failed chips with new ones. Some malfunctions may be due to the use of BGA soldering technologies in modern Main Board technologies. Typically, such defects are detected by local heating of the chip.
The malfunction of the TDA18275 tuner is established after checking the software and all the supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
Attention TV owners! Attempts at self-repair of the MYSTERY MTV-2426LT2 are not recommended by the manufacturer and can lead to serious negative consequences!
Repair MainBoard
The appearance of the MainBoard MS308C1-ZC01-01 is shown in the figure below:
MS308C1-ZC01-01
MS308C1-ZC01-01 can be used in TVs:
Haier LE32B8000T (Panel LSC320AN02-S01), JVC LT-32M340 (Panel LK315T3HB87 ), MYSTERY MTV-3230LT2 (Panel V320BJ7-PE1), MYSTERY MTV-2426LT2 (Panel V236BJ1-P03), MYSTERY MTV-2231LT2 (Panel LC215DT4A).
Main features of the MYSTERY MTV-2426LT2 device:
Installed matrix (LED panel) V236BJ1-P03.
The matrix control uses the Timing Controller (T-CON) V236BJ1-XC01.
To power the backlight LEDs, a converter is used, combined with the main board MS308C1-ZC01-01, controlled by the OB3350 PWM controller.
The power module is combined with the MainBoard and is made according to the flyback AC / DC voltage converter circuit using PWM SOT23-6 microcircuits.
MainBoard - the main board (motherboard) is an MS308C1-ZC01-01 module, using CPU chips: MSD308BEM, SPI Flash: GD25Q64, SOUND: TPA1517 or the like.

The TDA18275 tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: INNOLUX
Model: V236BJ1-P03
Type: a-Si TFT-LCD, CELL
Diagonal size: 23.6 inch
Resolution: 1366x768, WXGA
Display Mode: MVA, Normally Black, Transmissive
Active Area: 521.471x293.184 mm
Surface: Antiglare (Haze 1%)
Glass Depth: 0.50 + 0.50 mm
Transmissivity: 5.8% (with Polarizer)
Contrast Ratio: 3000: 1
Display Colors: 16.7M (8-bit)
Response Time: 8.5 (G to G)
Frequency: 60Hz
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 12.0V


MYSTERY MTV-2426LT2 TV with V236BJ1-P03 LCD display, 24 "(61 cm) diagonal size of 16: 9 format. The required brightness of the screen is 230 cd / m² by LED backlighting. Contrast, as the ratio of maximum brightness to minimum, is 1000: 1. Edge LED backlighting is implemented in the LED panel of this TV - Edge LED. You can view images in high quality HD at a resolution of 1366x768 pixels in the standard for graphic decomposition 720p (HD Ready). The input high-frequency or video signal can be processed in analog systems . Emah PAL, SECAM, NTSC Image processing and the formation of the digital signal is in 480i standards, 480p, 576i, 576p, 720p, 1080i Supported multimedia file formats:. MP3, WMA, MPEG4, Xvid, MKV, JPEG.
The power of the sound system 6 W (2x3 W) provide two speakers. It uses a NICAM stereo signal processing system and Sound Surround.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x2, component, VGA, HDMI x2, USB. 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, 1360x768.
A digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
Overall dimensions: 550x375x160 mm.
TV Weight: 4 kg.
Attention! The panel V236BJ1-P03 of the MYSTERY MTV-2426LT2 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.