Technical description and composition of the PANASONIC TX-20LB5P TV, panel type and modules used. The composition of the modules.PANASONIC
Model: TX-20LB5P
Chassis / Version: SL-115P
Panel: LC201V02 (A3) (KA)
Inverter (backlight): DS-1020WDL
PWM Inverter: BIT3105
MOSFET Inverter: APM4542
Power Supply (PSU): Adapter 12V
MainBoard: DLP-20D4LHS
IC MainBoard: VCT49X3F PY F 1000 (115P-20.050921), MST9883C, TDA1517P
Tuner: UV1316 / A I-4
TX-20LB5P Specifications
PANASONIC TX-20LB5P
General recommendations for TV LCD repair
Possible manifestations of defects
- TV PANASONIC TX-20LB5P does not turn on and does not show any signs of turning on, does not respond to control buttons and to the remote control.
With such manifestations, the adapter power supply usually fails.
This TV model is equipped with an external power supply of the Adapter 12V type, which the owner can purchase on his own, and its repair may not always be advisable, however, sometimes it makes sense to open it and eliminate simple typical defects typical for SMPS. It is necessary to measure its secondary output voltages, and if they are absent, check the power switches and rectifier diodes in the converters for a short circuit.
In case of diode breakdowns in the secondary circuits, the converter can operate in an emergency mode of short circuit without output voltages, and in case of a short circuit in the power elements of the primary circuit, the mains fuse and / or the current sensor in the source of the key usually breaks off.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements, which can disable it in key mode, or provoke an excess of the maximum current or voltage values. These can be circuits supplying the PWM controller, damper or frequency setting circuits, or OOS (negative feedback) elements in the stabilization circuit. PWM controllers (PWM), in the absence of external damage and a short circuit between the terminals, are checked by replacing them with a known good one.
- There is no image, there is sound, it reacts to the remote control. Or, immediately after switching on for a second, the image may appear and immediately disappear.
These manifestations can be triggered by the power module, or by defects in the inverter, as well as by skewed currents in the lamps due to their uneven wear. After checking all the electrolytic capacitors of the filters that participate in the power supply of the inverter, the power switches in its converter should be ringed for breakdown and the secondary windings of the transformers for an open circuit.
If, when diagnosing a malfunction, it is required to turn off the inverter protection, there is a risk of failure of the power elements of the inverter, and special care is required during work, and after they are completed, it is imperative to restore the protection circuits for further safe operation of the TV by the owner in normal mode.
- The TV does not go into operation, does not respond to the remote control. The indicator on the front panel is on or blinking.
Repair or diagnostics of the DLP-20D4LHS motherboard should begin with checking the stabilizers and power converters necessary to power the microcircuits and matrix. If necessary, you should update or replace the software (software). Sometimes it is necessary to check or replace (if necessary) the elements of the MainBoard - VCT49X3F PY F 1000 (115P-20.050921). In cases where a BGA processor is used, its malfunction is usually detected by a local warm-up method.
If the TV operates normally from external devices but does not tune to TV channels, the UV1316 / A I-4 tuner may be faulty. 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 reason for the inoperability of the tuner may be a software failure.
Attention! Users and owners of TX-20LB5P TVs who do not have the appropriate qualifications, knowledge and experience are strongly discouraged from attempting to repair themselves in order to avoid negative consequences that may lead to the complete non-repairability of the device.
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> PANASONIC TX-20LB5P Chassis SL-115P for models TX-20LB5F (WEST EUROPE), TX-20LB5P (EAST EUROPE)
The appearance of the MainBoard DLP-20D4LHS is shown in the figure below:DLP-20D4LHS
Main features of the PANASONIC TX-20LB5P device:
Installed matrix (LCD panel) LC201V02 (A3) (KA).
To power the backlight lamps, the DS-1020WDL inverter is used, controlled by the BIT3105 PWM controller. As the power elements of the inverter, keys of the APM4542 type are used.
To power all the internal units of the PANASONIC TX-20LB5P TV, an external adapter 12V is used.
MainBoard - the main board (motherboard) is a DLP-20D4LHS module, using VCT49X3F PY F 1000 (115P-20.050921), MST9883C, TDA1517P and others.
Tuner UV1316 / A I-4 provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG.Philips LCD
Model: LC201V02-A3KA
Type: a-Si TFT-LCD, Panel
Diagonal size: 20.1 inch
Resolution: 640x480, VGA
Active Area: 408x306 mm
PANASONIC TX-20LB5P TV with LCD display LC201V02, diagonal size 20 "4: 3. Contrast, as the ratio of maximum brightness to minimum, is 600: 1. Input analog video signal can be processed in PAL, SECAM, NTSC systems. Graphic processing and formation of a digital signal picture takes place in the 480i, 480p, 576i standards.
The power of the acoustic audio system is 6 W (2x3 W), provided by two speakers. NICAM STEREO sound processing system is used.
External interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV. A headphone output is provided for individual listening.
Dimensions: with stand 608x458x215 mm, without stand 608x403x74 mm.
TV weight: without stand: 10.1 kg.
Attention! The LC201V02 (A3) (KA) panel of the PANASONIC TX-20LB5P LCD TV is a rather expensive component.
Avoid impacts on the glass and pressure on the screen surface to avoid irreversible damage to the LCD panel!