Technical description and composition of the BBK LT2731S TV, panel type and applicable modules. The composition of the modules.BBK
Model: LT2731S
Panel: V260B1-L02 revC1
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: MAIN_PCB
Tuner: TDQ-6FT / W126H
Appearance
BBK LT2731S
General recommendations for repairing TV LCD
Possible manifestations of defects
- The BBK LT2731S TV does not turn on at all. There is no reaction to the remote control or to the control buttons from the front panel. Indicator lights do not light or flash.
Typically, with such manifestations, the defect is caused by faulty elements in the HLP-20A11 main power module. It is necessary to measure the secondary output voltages, 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 main fuse usually 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 key can be PWM (PWM) FAN7602, FAN7530 (PFC), FAN7382. It is checked only by replacement with a known good one.
- There is no image, but there is sound and reaction to the remote control. Or for a second, the image may appear immediately after switching on.
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 inverter. If all the electrolytic capacitors of the filter according to the power supply of the inverter are working, make sure that the lamps are working, then you need to check the converter keys and the secondary windings of the transformers.
If in diagnosing a malfunction, it is necessary to disable the inverter protection, there is a risk of failure of the power elements of the inverter, and special care is required when working, and after they are finished, it is necessary to restore the protection circuits for further safe operation of the TV by the owner in normal mode.
- The indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the MAIN_PCB motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software).
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 terminals. 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.
Once again, remind users! Attempts to self-repair a BBK LT2731S TV without the appropriate qualifications and necessary experience can lead to its complete non-repairability!
The HLP-20A11 power module is installed in the LT2731S TV using the PFC (Power Factor Correction) scheme acting as an active filter to eliminate the higher harmonic components of the current consumption. The boost converter based on the FAN7530 PWM controller does not allow the electrolytic capacitor of the input rectifier filter to be connected directly to the network directly through open diodes, when the value of the charge current determines its reactance (about 15-30 ohms at a frequency of 50 Hz). As a result of the conversion, the charging current of the capacitor will be determined in such a way that the envelope of the high-frequency pulses of the input current will repeat the phase and shape of the sine wave of the input voltage. The health check of the PFC unit is carried out by measuring the DC voltage on the capacitor of the rectifier network. In operating mode, it should be around 380V, in standby approximately 300V.
The appearance of the power supply
Main features of the BBK LT2731S device:
Installed matrix (LCD panel) V260B1-L02 revC1.
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 TV BBK LT2731S are generated by the HLP-20A11 power module, or its analogs using FAN7602, FAN7530 (PFC), FAN7382 microcircuits.
MainBoard - the main board (motherboard) is a MAIN_PCB module.
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)