Technical description and composition of the BBK LT2621S TV, panel type and applicable modules. The composition of the modules.BBK
Model: LT2621S
Chassis / Version: RSAG7.820.1269 / ROH_Ver.C
Panel: V260B1-L02
Inverter (backlight): integrated into PSU
PWM Inverter: FAN7313
Trans Inverter: BCQ-EEA17-HA
Power Supply (PSU): HLP-20A11 RSAG7.820.1235 / ROH
PWM Power: FAN7602, FAN7530 (PFC), FAN7382
MainBoard: RSAG7.820.1269 / ROH_Ver.C LCD26W60
IC MainBoard: MST9E19B-LF, LCD-CM1671A, A25L40PTO, 24C32, 24C08, 24C04, TDA7266,
Tuner: TDQ-6FT / W126H
Technical Specifications LT2621SU
BBK LT2621S
General recommendations for repairing TV LCD
Possible malfunctions
- BBK LT2621S TV does not turn on at all. The control lights do not light or flash. On the remote control and the buttons on the control panel does not respond.
In most of these cases, the HLP-20A11 main switching power supply is faulty. It is necessary to measure its secondary output voltage, and in case of their absence, check the serviceability of the power switches of the converters and rectifier diodes for a short circuit.
In case of breakdowns in the secondary circuits, the converter can operate in a short circuit mode, and during short circuit in the elements of the primary circuit, the mains fuse usually breaks.
The breakdown of Mos-Fet keys used in pulsed sources is often caused by malfunctions of other elements, for example, power supply, frequency-setting, damper ... as well as elements of the Negative Stabilization Feedback. PWM chip FAN7602, FAN7530 (PFC), FAN7382 can also cause a malfunction of the power switch of the converter and is checked by replacement.
- There is no image, there is sound, it is responding to the remote control. Or immediately after turning on for a second, the image may appear and immediately disappear.
The defect can be caused by problems in the nodes or elements of the backlight of the display, or in the power supply of the lamps or the inverter.After checking all the electrolytic capacitors of the filters that are involved in the power supply of the inverter, you must ring in its converter power keys for breakdown and secondary windings of transformers for an open.
Sometimes, for diagnostic purposes, inverter protection must be disabled. In such cases, special care must be taken during work, and the protection circuits should be restored immediately after the repair is completed.
- The indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the RSAG7.820.1269 motherboard should begin by checking the stabilizers and power converters needed to power the microcircuit 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 - MST9E19B-LF, LCD-CM1671A, A25L40PTO, 24C32, 24C08, 24C04, TDA7266, and replace failed chips with new ones. Some malfunctions can 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 the TV works normally from external devices, but does not tune into television channels, the TDQ-6FT / W126H tuner may be malfunctioning. In such cases, first of all, you should make sure that there are supply voltages at its corresponding conclusions. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus. Sometimes the cause of the inoperability of the tuner may be a software failure.
It should be remembered! Attempts to independently repair the BBK LT2621S 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!
Service Manual with Schematic Diagram 46 pages 2006 on model LT2619SU, LT2621SU
The appearance of the MainBoard RSAG7.820.1269 is shown in the figure below:RSAG7.820.1269
RSAG7.820.1269 can be used in TVs:
BBK LT2617S (Panel V260B1-L02 rev.c1), BBK LT2621S (Panel V260B1-L02), BBK LT3221S (Panel V315B1-L01 Rev.C2), BBK LT3217S (Panel AX080D002F), BBK LT3219S (Panel V315B1-L01 Rev.C2).
PSU Advanced
According to the conditions of compliance with modern world standards for household switching power supplies, the HLP-20A11 module provides for the use of a Power Factor Correction unit. The PFC circuit is a flyback converter based on the FAN7530 PWM controller. The reactance of an electrolytic capacitor of a line filter at a frequency of 50-60 Hz is usually not more than 20-30 ohms and its charge directly from the network through open diodes could reach tens of amperes per pulse if no filtering were applied.
As a result of the PFC conversion, an increased voltage on the capacitor (about 380V) cannot directly open the rectifier diodes, on the anode of which the voltage will always be slightly less (about 300V) and then its charging current will always be limited by the elements of the PWM controller. As a result, the envelope of the high-frequency pulses of the consumed current will repeat the shape and phase of the input sinusoidal voltage. The presence of an increased voltage (+ 380V) on the network capacitor indicates the serviceability of the PFC node.
The appearance of the power supply
Main features of the BBK LT2621S device:
Installed matrix (LCD panel) V260B1-L02.
To power the backlight, a converter is used, combined with the power supply, controlled by the FAN7313 PWM controller. A transformer BCQ-EEA17-HA is installed in the inverter converter.
The necessary supply voltages for all nodes of the BBK LT2621S TV are generated by the HLP-20A11 power module, or its analogs using FAN7602, FAN7530 (PFC), FAN7382 microcircuits.
MainBoard - the main board (motherboard) is an RSAG7.820.1269 module, using microcircuits MST9E19B-LF, LCD-CM1671A, A25L40PTO, 24C32, 24C08, 24C04, TDA7266, and others.
The TDQ-6FT / W126H tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: CMO
Model: V260B1-L02
Type: a-Si TFT-LCD, Panel
Diagonal size: 26.0 inch
Resolution: 1366x768, WXGA
Display Mode: TN, Normally White, Transmissive
Active Area: 575.769x323.712 mm
Brightness: 450 cd / m²
Contrast Ratio: 800: 1
Display Colors: 16.2M (6-bit + FRC), CIE1931 72%
Response Time: 3/5 (Tr / Td)
Frequency: 60Hz
Lamp Type: 4 pcs CCFL Without Driver
Signal Interface: RSDS (1 Channel), 45 pins
Voltage: 5.3.3 / 5.0V (VDD / VIN5)
BBK LT2621SU LCD TV with 26 "(66 cm) diagonal LCD display in 16: 9 format. The brightness of the screen is 500 cd / m² by CCFL (EEFL) fluorescent lamps. The ratio of maximum brightness to minimum (contrast) is 800 : 1. 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). 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, MPEG4, JPEG.
The power of the sound system 12 W (2x6 W) provide two speakers. The audio processing system NICAM STEREO is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x3, S-Video, component, SCART x2, RGB, 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.
The power consumed by the TV in the operating mode from the network is 140 watts.
Overall dimensions: 665x505x210 mm.
TV mass: 12 kg.
Attention! The BBK LT2621SU LCD TV panel is its most expensive component.
Avoid hitting the glass and exerting pressure on the screen to avoid permanent damage to the LCD panel!