REPAIR / SERVICING TV SUPRA STV-LC2725AFL

Technical description and composition of the SUPRA STV-LC2725AFL TV, panel type and modules used. The composition of the modules.
SUPRA LED
Model: STV-LC2725AFL
Chassis / Version: V5L11
Panel: M270HGE-L21
LED driver (backlight): integrated into PSU
PWM LED driver: OB3370NCP
MOSFET LED driver: AOD417, ME45P04
Power Supply (PSU): LK-PL270401A
PWM Power: GR8876A
MOSFET Power: ME15N10-G
MainBoard: T.VST59S.73
IC MainBoard: CPU: TSUMV59XES-Z1, SPI FLASH: GD25Q32
Tuner: CDT-3NP5 / 1-10
Control: Login to the service: MENU 1147
STV-LC2725AFL Specifications
SUPRA STV-LC2725AFL
General recommendations for TV LCD LED repair
Repair of electronic equipment usually begins with its external examination and diagnosis of a malfunction. In this case, you should inspect all the internal components of the SUPRA STV-LC2725AFL TV, as well as the external elements of the case. Often, according to certain external signs, it may be possible to draw certain conclusions about the reasons for the failure of certain elements of the circuit even before taking the necessary measurements, which will make it possible to determine a further algorithm for troubleshooting and localizing a defect. Electrolytic capacitors of filters with a swollen case, as well as ring cracks formed in the soldering of the leads of heating elements or a layer of coal on burnt resistors sometimes prompt the repairman about the causes of the malfunction and the possible consequences.
Sometimes the SUPRA STV-LC2725AFL TV just won't turn on. No control lamps on the front panel are on or blinking, the TV does not respond to the remote control and does not emit any sounds or any signs of life when turned on. The most likely cause of a malfunction is the failure of the common power module. If it is working properly, you need to check the processor batteries on the SSB (Main Board). The first step is to replace the swollen capacitors of the rectifier filters, if any. If the mains fuse in the power supply is broken, in most cases a breakdown of the power switch (s) is detected, which can be integrated with the PWM controller, or a separate field-effect transistor can be used. You should also check the diodes of the rectifier bridge and the electrolytic capacitor of the mains rectifier filter.
It should be remembered that in the practice of repair, usually power switches in switching power supplies (SMPS) do not fail due to their poor quality and, in such cases, it is necessary to look for the reason that led to a malfunction and provoked a breakdown of the key. Most often, the culprits of the accident are dry electrolytic capacitors or broken resistors in the primary circuit, or the PWM controller microcircuit itself may be faulty. It is also necessary to check all the semiconductor elements of the stabilization circuit in the primary and secondary circuits.
If SUPRA STV-LC2725AFL has no picture but sound, the M270HGE-L21 panel backlight LEDs or their power converter may be faulty. You should also make sure that the electrolytic capacitors of the secondary rectifiers of the common power supply are in good working order.
To check the health of the LEDs, as well as the contact connections in the ruler circuit, the panel must be disassembled.
When diagnosing, it must be borne in mind that it is impossible to check for an open in the circuit of the LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally a current source.
Repair of the T.VST59S.73 motherboard must begin with diagnostics and testing of all linear stabilizers or power converters of its microcircuits. Sometimes it may be necessary to update the software (software) - flashing FLASH or EEPROM.
Complex repair of MB (SSB) board is in some cases possible and practiced by repairmen. To do this, check and, if necessary, replace the CPU elements: TSUMV56XES-Z1, SPI FLASH: GD25Q32. Malfunctions in BGA chips are usually easy to detect by warm-up.
If you suspect a malfunction of the CDT-3NP5 / 1-10 tuner, first of all, you need to make sure that there is a supply voltage of varicaps (30-33V) at the corresponding output of the tuner, as well as other voltages supplying it.

Remember! Attempts to repair the SUPRA STV-LC2725AFL TV, in the absence of the necessary qualifications and experience, are categorically not recommended and are fraught with negative consequences, up to the complete non-repairability of the device!

FIRMWARE FOR SPI FLASH  ----------->   SUPRA STV-LC2725AFL (V5L11), MAIN T.VST59S.73, PANEL M270HGE-L21

FIRMWARE FOR SPI FLASH  ----------->   SUPRA STV-LC2725AFL V6M03, MAIN:T.VST59S.73, CPU:TSUMV59XES, PANEL:V260H1-LE2 Rev.C2

 In case of a malfunction in the software of the SPI FLASH chip produced by Winbond, we recommend changing it to a new one. Sometimes faulty SPI Winbond microcircuits can be temporarily restored after the soldering station warms up with a hairdryer. This is usually enough to read its contents.

Additional MainBoard Repair

The appearance of the MainBoard T.VST59S.73 is shown in the figure below:
T.VST59S.73
It is advisable to start repairing the T.VST59S.73 motherboard, made on the basis of the multipurpose TSUMV59Xxx processor, by checking the operability of linear stabilizers or voltage converters necessary to supply power to the processor nodes - power supply of the core 1.2V, DDR memory 1.8V and Stand-by 3.3V mode ... In the absence of an image, but with a working backlight of the display, you should check the supply voltage of the LCD panel 5V or 12V, depending on the type of panel used.
T.VST59S.73 can be used in TVs:
SUPRA STV-LC3265FL (Panel V315H3-LE3 Rev.C1), SUPRA STV-LC2725AFL (Panel M270HGE-L21).
External view of the power supply
Main features of the SUPRA STV-LC2725AFL device:
Installed matrix (LED-panel) M270HGE-L21.
A converter combined with a power supply is used to power the backlight LEDs and is controlled by the OB3370NCP PWM controller. The keys of the type AOD417, ME45P04 are used as power elements of the LED driver.
The formation of the necessary supply voltages for all nodes of the SUPRA STV-LC2725AFL TV is carried out by the LK-PL270401A power module, or its analogs using GR8876A microcircuits and ME15N10-G power switches.
MainBoard - the main board (motherboard) is a T.VST59S.73 module, using CPU chips: TSUMV59XES-Z1, SPI FLASH: GD25Q32 and others.
The CDT-3NP5 / 1-10 tuner provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: CHIMEI INNOLUX
Model: M270HGE-L21
Type: a-Si TFT-LCD, Panel
Diagonal size: 27.0 inch
Resolution: 1920x1080, FHD
Display Mode: TN, Normally White, Transmissive
Active Area: 597.888x336.312 mm
Surface: Glare (Haze 0%), Hard coating (3H), Reflection 5.0% (Max.)
Brightness: 300 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (6-bit + Hi-FRC)
Response Time: 0.8 / 2.6) (Tr / Td)
Frequency: 60Hz
Lamp Type: 4 strings WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 30 pins
Voltage: 5.0V
SUPRA LED TV STV-LC2725AFL with LCD M270HGE-L21, diagonal size 27 "(69 cm) 16: 9 format. The required screen brightness of 400 cd / m² is provided by LED backlighting. Contrast - the ratio of maximum brightness to minimum is 3500: 1. Dynamic contrast ratio of 70,000: 1 is achieved by special control of the LEDs depending on the illumination of areas in the scene.This model uses an LED-panel with an edge LED backlighting - Edge LED. The capabilities of the TV provide viewing of programs and films in high quality HD at resolution of 1920x1080 pixels in graphic resolution according to the standard 1080p (Full HD) .Input high-frequency or video signal is decoded in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal formation occurs in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p Supported media file formats: MP3, WMA, MPEG4, JPEG.
Speaker power 20 W (2x10 W) is provided by two speakers. Uses NICAM stereo signal processing system and Sound Surround function.
External interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV x2, audio x2, component, SCART, RGB, VGA, HDMI x3, 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.
The power consumed by the TV in operating mode from the network is 60 watts.
Dimensions: With stand 793x565x205 mm, Without stand 793x508x89 mm.
Attention! The panel M270HGE-L21 of the SUPRA STV-LC2725AFL 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.