Saturday 21 March 2020

REPAIR / SERVICING TV BBK LT2619S

Technical description and composition of the BBK LT2619S TV, panel type and applicable modules. The composition of the modules.
BBK
Model: LT2619S
Panel: V260B1-L02
T-CON: RSAG7.820.1330 / ROH Ver.C
Inverter (backlight): integrated into PSU
PWM Inverter: FAN7313
Trans Inverter: BCQ-EEA17-HA
Power Supply (PSU): HLP-20A11 - RSAG7.820.1235 / ROH ver.f
PWM Power: FAN7602, FAN7530 (PFC), FAN7382
MainBoard: RSAG7.820.1529 / ROH VER C, RSAG7.820.1272 / ROH VER B
IC MainBoard: TDA9886TS, TE330, CM1671A-KQ, AML7213R
Tuner: TDQ-6FT / W126HROH
Technical Specifications LT2619SU
BBK LT2619S
General recommendations for repairing TV LCD
Possible manifestations of defects
- The BBK LT2619S 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.
Most often, with such manifestations, the HLP-20A11 main power module is found to be 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, but there is sound, it reacts to the remote control. Or the image appears when you turn it on and immediately disappears
These manifestations can be triggered by a power module, or by defects in the inverter, as well as a distortion of the currents in the lamps due to their uneven wear. If all the electrolytic capacitors of the filter according to the inverter power supply are serviceable, you should make sure that the lamps are working, then you need to check the converter keys and the secondary windings of the transformers.
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 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 RSAG7.820.1529 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). In cases of attempts to repair the MB board (SSB), it is necessary to check the serviceability of its elements - TDA9886TS, TE330, CM1671A-KQ, AML7213R which may require replacement with new ones. If a BGA processor is installed, there is a possibility of a violation of the soldering of the contacts of its conclusions with the board (it is diagnosed by heating).
If there is no reception of television channels, but the TV is working properly from external devices, first of all you need to check the power supply of the TDQ-6FT / W126HROH tuner and update the software. The pulses from the I2C bus must be controlled with an oscilloscope.
Once again, we remind TV users: you should not make attempts to repair it yourself without the appropriate knowledge, experience and the necessary qualifications! Entrust repair to professionals with sufficient experience in the field of repair of electronic equipment.
 Service Manual with Schematic Diagram 46 pages 2006 on model LT2619SU, LT2621SU




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 the electrolytic capacitor of the 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 LT2619S device:
Installed matrix (LCD panel) V260B1-L02.
The matrix control uses the Timing Controller (T-CON) RSAG7.820.1330.
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 LT2619S are generated by the HLP-20A11 power module, or its analogs using FAN7602, FAN7530 (PFC), FAN7382 microcircuits.
MainBoard - the main board (motherboard) is an RSAG7.820.1529 module, using TDA9886TS, TE330, CM1671A-KQ, AML7213R and other chips.
The TDQ-6FT / W126HROH tuner provides TV reception and channel tuning.
Information from an alternative source:
BBK LT1919S, LT2619S, LT3219S
Panel Type (Matrix): V260B1-L02,
Motherboard: RSAG7.820.1529 / ROH VER C, TDA9886TS, TE330, CM1671A-KQ, Tuner: TDQ-6FT / W126H \ ROH, USB: RSAG7.820.1272 / ROH VER B., AML7213R
T-con: RSAG7.820.1330 / ROH Ver.C
PSU & Invertor: RSAG7.820.1235 / ROH ver.f HLP-20A11
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)