Technical description and composition of the BBK LT1917S TV, panel type and applicable modules. The composition of the modules.BBK
Model: LT1917S
Chassis / Version: RSAG7.820.1264 / ROH_Ver_C
Panel: 19 inch
Inverter (backlight): integrated into PSU
Power Supply (PSU): JSI-190411
MainBoard: RSAG7.820.1264 / ROH_Ver_C LCD19W57
IC MainBoard: MST9E19B-LF, TDA9886, A25L40, 24C32, 24C04, TDA1517P
Tuner: TDQ-6FT / W126H
Technical Specifications LT1917S
BBK LT1917S
General recommendations for repairing TV LCD
Possible malfunctions
- BBK LT1917S does not turn on, the indicators on the front panel do not light or flash. The TV does not respond to the control buttons and the remote control.
In the vast majority of such cases, a malfunction is detected in the power module. It is necessary to measure its 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 switch may be PWM (PWM). It is checked only by replacement with a known good one.
- 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.
These manifestations can be triggered by a power supply module, or by inverter defects, as well as by distortion of the currents in the lamps due to their uneven wear. After checking all the electrolytic capacitors of the filters that are involved in the power supply of the inverter, it is necessary to ring in its converter the power switches for breakdown and the secondary windings of the transformers for an open.
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 RSAG7.820.1264 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). Board repair and replacement of MST9E19B-LF, TDA9886, A25L40, 24C32, 24C04, TDA1517P microcircuits are carried out with the necessary equipment, and the corresponding element base. Faults associated with the application of BGA processor soldering technologies can be localized by the heating method.
Before replacing the TDQ-6FT / W126H tuner, if there is no channel tuning, you must first check the software and the supply voltage at its terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus
Once again, remind users! Attempts to self-repair a BBK LT1917S TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
Service Manual with Schematic Diagram 60 pages of 2008 on the LT1921S, LT2621S, LT3221S, LT1919S LT2619S, LT3219S, LT1917S, LT2617S
The appearance of the MainBoard RSAG7.820.1264 is shown in the figure below:RSAG7.820.1264
The appearance of the power supply
Main features of the BBK LT1917S device:
Installed matrix (LCD-panel) 19 inches.
To power the backlight, a converter is used, combined with a power supply.
The formation of the necessary supply voltages for all nodes of the BBK LT1917S TV is carried out by the JSI-190411 power module, or its analogues.
MainBoard - the main board (motherboard) is an RSAG7.820.1264 module, using microchips MST9E19B-LF, TDA9886, A25L40, 24C32, 24C04, TDA1517P and others.
The TDQ-6FT / W126H tuner provides TV reception and channel tuning.
BBK LT1917S LCD TV with 19 "LCD, 19" (48 cm) diagonal of 16:10 format. Screen brightness of 300 cd / m² is ensured by backlighting with 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 1440x900 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 the standards 4 80i, 480p, 576i, 576p, 720p, 1080i.
The power of the sound system 3 W (2x1.5 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, RGB, VGA, HDMI. 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, 1360x768.
The power consumed by the TV in the operating mode from the network is 45 watts.
Overall dimensions: 468x399x178 mm.
TV Weight: 5.5 kg.
Attention! The 19-inch panel of the BBK LT1917S LCD TV is its most expensive component.
Avoid hitting the glass and exerting pressure on the screen to avoid permanent damage to the LCD panel!