Technical description and composition of the PANASONIC TX-42AS650 TV, panel type and modules used. The composition of the modules.PANASONIC LED
Model: TX-42AS650
Chassis / Version: LA51
Panel: LC420DUF (VG) (F1)
LED backlight: 6916L-1809A
T-CON: 14Y_RA_EF12TA2MB4C2LV0.3
LED driver (backlight): integrated into PSU
PWM LED driver: BD9479FV
Power Supply (PSU): TNPA5944 1 P
PWM Power: FA5696N, FA5760N, NR131S
MainBoard: TNPH1077 1 A
IC MainBoard: CPU: MN2WS0280, EMMC: THGBM5G5A1JBAIR, EEPROM: 24C16
Tuner: TDSA-G370D
TX-42AS650E Specifications
PANASONIC TX-42AS650
General recommendations for TV LCD LED repair
Possible manifestations of malfunctions
- PANASONIC TX-42AS650 does not turn on, indicators on the front panel do not light or flash. The TV does not respond to the control buttons and the remote control.
In such cases, the TNPA5944 power supply usually fails. Its output voltages should be measured, and if they are absent, check the serviceability of the power switches of the converters and rectifier diodes for the probability of a short circuit.
In case of any breakdowns in the secondary circuits, the converter can operate in an emergency mode of a short circuit, and with a short circuit in the power elements of the primary circuit, the mains fuse or the current sensor in the source of the key is often cut 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) FA5696N, FA5760N, NR131S, in the absence of external damage and 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 the image may appear for a second when turned on and disappear immediately.
The malfunction in most of these cases is found in the nodes and elements of the LED panel backlight. The reason for this may be an open circuit in the LED circuit, or a problem in stabilizing their power supply.
It is impossible to identify an open circuit in the LED line without disassembling the panel with a simple multimeter. The LEDs are connected in series and a voltage of several tens of volts is required to open their junctions. Ideally, a current source is suitable for such purposes. You can open the panel and check each LED separately. Usually, Chinese multimeters lightly light up one 3-volt LED if you connect the probes to it in the forward direction (red probe to the anode, black to the cathode). For dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of the LED health. In the event of a malfunction of the LED, its zener diode will either be cut off, or broken through in the K / Z.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals the standby mode.
Repair or diagnostics of the TNPH1077 motherboard should begin with checking the stabilizers and power converters necessary to power the microcircuits and the matrix. If necessary, you should update or replace the software (software). Complicated MB (SSB) repair is possible only in the conditions of a service center with the necessary equipment. Checking or replacing CPU: MN2WS0280, EMMC: THGBM5G5A1JBAIR, EEPROM: 24C16 requires the necessary training and professional skills to repair modules at the component level. Problems associated with the use of BGA soldering technologies can sometimes be diagnosed by the warm-up method.
In cases where there is no tuning for terrestrial or cable TV channels, you should make sure that the software is correct, as well as that the supply voltages on the TDSA-G370D tuner outputs match. It is also necessary to check with an oscilloscope the presence of pulses of data exchange between the tuner and the processor via the I2C bus.
If the PANASONIC TX-42AS650E has no image, but there is sound, the display backlight often simply does not work. Moreover, in LED TVs, the LEDs inside the panel usually fail, less often the LED driver.
In such cases, you can see a barely noticeable image with a successful hit of external light on the screen.
Replacing the LEDs requires disassembling the LCD panel - a process that requires experience and qualifications from the master. We do not recommend doing such work on your own to the owners of TVs and craftsmen who do not have experience in repairing LCD panels
If there is no image, and the backlight is on, the screen becomes slightly lighter when turned on, and in an open TV you can see the light through the holes in the panel case.
In this case, the panel may also be faulty - damage to strips, loops, for example, as a result of moisture ingress after unsuccessful washing of the screen, the T-CON (Timing Controller) board may be faulty. But often the main board MainBoard turns out to be faulty, a software failure is also possible.
Then, first of all, it is necessary to check the panel supply voltage, the fuses on the T-CON board, as well as the supply and reference voltages of the column and line drivers - VGH, VGL, Vcom.
If these measurements are within normal limits, it is necessary to trace the passage of LVDS signals from the MainBoard with an oscilloscope, as well as synchronization signals to the loops with drivers.
Flooded or unsuccessfully washed screens of LED-TVs can be restored, in about half of the cases, usually if significant damage has not formed in the cables and panel strips.
Remember! Attempts to self-repair the PANASONIC TX-42AS650 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!
DOWNLOAD SCHEMATIC DIAGRAM / SERVICE MANUAL ------------------> PANASONIC TX-42AS650 Chassis LA51 for TX-42AS650B, TX-42AS650E
The MainBoard TNPH1077 is shown in the figure below:TNPH1077
External view of the power supply
The main features of the PANASONIC TX-42AS650 device:
Installed matrix (LED panel) LC420DUF (VG) (F1).
Matrix management uses Timing Controller (T-CON) 14Y_RA_EF12TA2MB4C2LV0.3.
To power the backlight LEDs, a converter combined with a power supply is used, controlled by a BD9479FV PWM controller.
The formation of the necessary supply voltages for all nodes of the PANASONIC TX-42AS650 TV is carried out by the TNPA5944 power module, or its analogs using the FA5696N, FA5760N, NR131S microcircuits.
MainBoard - the main board (motherboard) is a TNPH1077 module using CPU: MN2WS0280, EMMC: THGBM5G5A1JBAIR, EEPROM: 24C16 and others.
The TDSA-G370D tuner provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUF-VGF1
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: IPS, Normally Black, Transmissive
Lamp Type: WLED
TV PANASONIC TX-42AS650E with LCD display, diagonal size 42 "(107 cm) 16: 9 format. The technology of production of the screen of this TV model is realized with LED backlighting.
There is support for 3D images using passive polarization technology.
The panel and motherboard firmware provide HD and Full HD viewing at 1920x1080 pixels in 1080p (Full HD) graphics.
The TX-42AS650E is equipped with SMART software, built-in applications and the ability to work on the Internet. Internet connection can be made via Wi-Fi wireless connection. The input analog video signal can be processed in PAL, SECAM, NTSC systems. Graphic processing and formation of a digital signal picture occurs in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Multimedia file formats supported by the video processor: MP3, WMA, MPEG4, MKV, JPEG.
The power of the acoustic audio system is 20 W (2x10 W) provided by two speakers. Uses NICAM stereo signal system and Sound Surround function.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, component, SCART, RGB, HDMI x3, USB x2, Ethernet (RJ-45), Bluetooth, Wi-Fi 802.11n. A headphone output is provided for individual listening. To connect a computer or laptop, a VGA (D-Sub 15) connector is used that supports resolutions: 640x480, 800x600, 1024x768, 1280x1024, 1360x768, 1920x1080.
The digital tuner is capable of receiving terrestrial and cable channels in the DVB-T MPEG4, DVB-C, DVB-T2 standards.
The power consumed by the TV in operating mode from the network is 96 watts.
Dimensions: with stand 962x608x202 mm, without stand 962x562x54 mm.
TV weight: with stand: 11 kg, without stand: 10 kg.
Attention! The panel of the PANASONIC TX-42AS650E LED TV is the most expensive element.
Do not allow any impact on the glass and pressure on the screen surface to avoid damage to the LED panel!
It is unsafe for liquid to spill onto the screen. Sometimes one drop is enough if it drips down the glass onto the cables to make the TV unrepairable.