Tuesday, 28 April 2020

REPAIR / SERVICING TV MYSTERY MTV-1924LT2

Technical description and composition of the MYSTERY MTV-1924LT2 TV, type of panel and applicable modules. The composition of the modules.
MYSTERY LED
Model: MTV-1924LT2
Chassis / Version: MSDV3222-ZC01-01 Ver V2N03
Panel: HT185WXF-100
T-CON: HW185WX3-400
LED driver (backlight): integrated into MainBoard
PWM LED driver: AP3039AM-G1, AP3608EM
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MainBoard: MSDV3222-ZC01-01
IC MainBoard: CPU: MSD308BT-SW, SPI Flash: GD25Q64B, EEPROM T-con 24C16, Scaller: NT71263FG-300
Technical Specifications MTV-1924LT2
MYSTERY MTV-1924LT2
General repair guidelines for TV LCD LED
Repair of electronic equipment usually begins with its external inspection and diagnosis of the malfunction. In this case, you should examine all the internal components of the MYSTERY MTV-1924LT2 TV, as well as the external elements of the case. Based on visible external changes in the state of the components, it is usually possible to determine the further direction of troubleshooting and localization of the defect before making the necessary measurements. In most cases, the repairman can guess the causes of the defect and possible consequences by the characteristic signs of typical TV defects, for example, ring cracks formed in the soldering of element leads, swollen rectifier filter capacitors, charred resistors and other circuit elements.
If the MYSTERY MTV-1924LT2 does not turn on, no control lights on the front panel light up or blink, therefore, there is a very high probability of a power module malfunction. In some cases, only the processor power regulator may be faulty. It is advisable to start the troubleshooting of the power supply module by checking the state of the electrolytic capacitors of the rectifier filters and the mains fuse. Defective capacitors should be replaced. If the mains fuse is broken, it is necessary to check first of all the power semiconductor elements - rectifier diodes and transistors, which are often found in such a state of breakdown.
In most cases, key breakdowns in switching power supplies (SMPS) do not occur for no reason and you should look for other faulty circuit elements that could provoke a defect. This can be dried electrolytic capacitors in the primary circuit, and faulty damper elements, as well as dangling resistors or punched semiconductor elements in the stabilization circuits. Possible defective PWM chip from the manufacturer.
If, when you turn on the TV, the image appears and immediately disappears, or is absent initially when you turn on, but the sound is there and other functions work, there is a high probability of a malfunction of the LED driver (power converter for the backlight LEDs of the HT185WXF-100 panel). In such cases, the general power module is also subject to verification, in which the electrolytic capacitors of the rectifier filter supplying the LED driver should be checked.
A malfunction in the backlight circuits often occurs due to an open in the power circuit of the LED lines. It requires disassembling the panel and checking the LEDs themselves, the rations of their terminals, as well as the reliability of the connections in the connectors and rations of the terminals.
It is impossible to check the LED line for breaks without disassembling the panel with a multimeter or tester. For these purposes, it is necessary to open all series-connected PN junctions and a voltage of the order of tens of volts will be required, and ideally, a current source.
Diagnostics and repair of the motherboard MSDV3222-ZC01-01 is carried out by checking the performance of the stabilizers or power converters of the module chips. In some cases, a software update is required.
In some cases, it is necessary to check or replace (if necessary) the elements of the MB board (SSB) - CPU: MSD308BT-SW, SPI Flash: GD25Q64B, EEPROM T-con 24C16, Scaller: NT71263FG-300. In cases where the BGA processor is used, its malfunction is usually detected by the local heating method.
Owners and users of the MYSTERY MTV-1924LT2 TV must remember that self-repair without special knowledge, skills and qualifications can be fraught with negative consequences that can lead to complete non-repairability of the device!


FIRMWARE FOR SPI FLASH  ----------->   MYSTERY MTV-1924LT2, Main: MSDV3222-ZC01-01, Panel: HT185WXF-100

SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    MYSTERY MTV-3224LT2 Chassis MSDV3222-ZC01-01 (MSDV3222-YL01-01)


 To reduce the backlight current in LED drivers with the AP3039AM controller and the AP3608EM terminal stage (AP3039AM-G1 & AP3608EM-G1), the AP3608EM (AP3608E) microcircuit should proportionally increase the resistor from terminal 14 (ISET) to the housing. The maximum current in each channel (in milliamperes) for the Rset resistor (in kilo-ohms) is determined from the ratio 1.194V / Rset. In channels connected in parallel, the currents add up.
Repair MainBoard
The appearance of the MainBoard MSDV3222-ZC01-01 is shown in the figure below:
The motherboard MSDV3222-ZC01-01 is made on a single chassis with a power module and an inverter to power the LED panel. The MSD308BT-SW multi-function control processor with built-in scaler is used. Repair of the power module is carried out according to standard technology - verification of power cells, electrolytic capacitors and secondary supply voltages. The following is a functional check of stabilizers and converters for powering the internal nodes of the processor and LCD panel. It should be borne in mind that if there are problems with the software in the SPI Flash chips manufactured by WINBOND, it is advisable to replace the chip itself with the contents of the software.
MSDV3222-ZC01-01 can be used in TVs:
BBK LEM3284DT2 (Panel LSC320AN02), MYSTERY MTV-2229LT2 (Panel M215HTN01.1 ), MYSTERY MTV-2429LT2 (Panel M240HTN01.2), MYSTERY MTV-2223LT2 (Panel LC215DTBA), MYSTERY MTV-2431LT2 (Panel V236BJ1 600), MYSTERY MTV-1924LT2 (Panel HT185WXF-100), MYSTERY MTV-3228LT2 (Panel LK315T3HB94), MYSTERY MTV-3023LT2 (Panel MT3151A05), MYSTERY MTV-2228LT2 (Panel RUNTK0001ZDP2), MYSTERY MTV-1929LT2 (Panel V185BJ1-PE1), MYSTERY MTV-3223LT2 (Panel LC315TU3A), MYSTERY MTV-3224LT2 (Panel HV320WX2-20A), MYSTERY MTV-3028LT2 (Panel ST2751A01-3), MYSTERY MTV-2428LT2 (Panel V236BJ1-P01), MYSTERY MTV-2424LT2 (Panel HM236WU8-200 ), MYSTERY MTV-4030LT2 (Panel V400HJ6-PE1), MYSTERY MTV-3031LT2 (Panel V290BJ1-PE1), MYSTERY MTV-3226LT2 (Panel V320BJ7-PE1).
Main features of the MYSTERY MTV-1924LT2 device:
Installed matrix (LED-panel) HT185WXF-100.
The matrix control uses the Timing Controller (T-CON) HW185WX3-400.
To power the backlight LEDs, a converter is used, combined with the main board MSDV3222-ZC01-01, controlled by a PWM controller AP3039AM-G1, AP3608EM.
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 MSDV3222-ZC01-01 module, using CPU chips: MSD308BT-SW, SPI Flash: GD25Q64B, EEPROM T-con 24C16, Scaller: NT71263FG-300 and others.
The MYSTERY MTV-1924LT2 TV with an HT185WXF-100 LCD display, a 19 "(48 cm) diagonal size of 16: 9 format. The LED panel of this TV has LED backlighting - Edge LED. You can view images in high quality HD with Resolution 1366x768 pixels in the standard of graphic decomposition 720p (HD Ready). The input high-frequency or video signal can be processed in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation occurs in standards 480i, 480p, 576i, 576p, 720p, 1080i. Supported media file formats: MP3, 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: 800x600, 1024x768, 1360x768.
A digital tuner is capable of receiving television channels in the DVB-T, DVB-C, DVB-T2 standards.
Dimensions: With stand 642x444x209 mm, Without stand 570x345x70 mm.
Attention! The panel of the HT185WXF-100 MYSTERY MTV-1924LT2 LED TV is an expensive and unreliable element.
Avoid any impact on the glass and pressure on the screen surface 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.