Friday 4 September 2020

REPAIRING / SERVICING TV PANASONIC TX-R26LM70K

Technical description and composition of the PANASONIC TX-R26LM70K TV, panel type and modules used. The composition of the modules.
PANASONIC
Model: TX-R26LM70K
Chassis / Version: GLP21MA
Panel: LTA260W2 (6LP)
Lamp backlight: CCFL
T-CON: 260W3C4LV0.1
Inverter (backlight): SSI260WA
Power Supply (PSU): TNP0EP009
PWM Power: MR4040
MOSFET Power: integrated
MainBoard: TNP0EA009
IC MainBoard: CPU: VCT69XYP, EEPROM: 24C32WP, HDMI: SiI9023CTU-L
Tuner: ENGF7701GF (TNPOEB009 board)
Control: IR: TNP0EV009
Appearance
PANASONIC TX-R26LM70K
General recommendations for TV LCD repair
Possible manifestations of defects
- PANASONIC TX-R26LM70K does not turn on and does not show any signs of operability at all. Does not blink indicators and does not respond to control buttons.
In such cases, the TNP0EP009 power supply usually fails. Then we recommend measuring its output voltages and, if they are absent, you should check the serviceability of the power switches (integrated) and rectifier diodes of the converters for a possible short circuit.
In case of breakdowns in the secondary circuits, the converter, as a rule, can operate in an emergency in the short-circuit mode, and in case of a short circuit in the power elements of the primary circuit, the mains fuse is usually cut off.
Breakdown of Mos-Fet switches used in switching power supplies is often caused by malfunctions of other elements, for example, in the power supply circuit of the PWM regulator, in frequency setting or damper circuits, as well as in negative feedback stabilization. Microcircuits PWM (PWM) MR4040 are usually checked by replacing them with new ones, or knowingly working.
- There is no picture, but there is sound and reaction to commands from the remote control. Or the image appears immediately after switching on and disappears.
A defect can be caused by problems in the nodes or elements of the display backlight, or in the power supply of lamps or the inverter.After checking all the electrolytic capacitors of the filters that are involved in the power supply of the inverter, ring the power switches in its converter 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 necessary to restore the protection circuits for the 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 TNP0EA009 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). Sometimes it is necessary to check or replace (if necessary) elements of the MainBoard - CPU: VCT69XYP, EEPROM: 24C32WP, HDMI: SiI9023CTU-L. In cases where a BGA processor is used, its malfunction is usually detected by a local warm-up method.
Before changing the ENGF7701GF tuner (TNPOEB009 board), if it is not possible to tune to TV channels, you should make sure that there are supply voltages that must be measured at the corresponding tuner pins and check the software for correctness. The pulses of data exchange between the tuner and the processor can be monitored with an oscilloscope
Once again, we remind TV users: do not try to repair yourself without the appropriate knowledge, experience and the necessary qualifications! Trust the repairs to professionals with sufficient experience in the field of electronic repair.
Additional MainBoard Repair
The appearance of the MainBoard TNP0EA009 is shown in the figure below:
TNP0EA009
External view of the power supply
Main features of the PANASONIC TX-R26LM70K device:

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https://2.bp.blogspot.com/-9zTaa4rqMqg/X1JEatTrEbI/AAAAAAABFpg/ZhDwt0nf55w5LuxejZhx88tROmzx7icHwCK4BGAYYCw/s1600/TNP0EP009_DCE.jpgInstalled matrix (LCD panel) LTA260W2 (6LP).
Matrix control uses a Timing Controller (T-CON) 260W3C4LV0.1.
An SSI260WA inverter is used to power the backlight lamps.
The formation of the necessary supply voltages for all nodes of the PANASONIC TX-R26LM70K TV is carried out by the TNP0EP009 power module, or its analogs using MR4040 microcircuits and integrated power switches.
MainBoard - the main board (motherboard) is a TNP0EA009 module, using CPU: VCT69XYP, EEPROM: 24C32WP, HDMI: SiI9023CTU-L and others.
The ENGF7701GF tuner (TNPOEB009 board) provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: SAMSUNG
Model: LTA260W2-L16
Type: a-Si TFT-LCD, Panel
Diagonal size: 26.0 inch
Resolution: 1366x768, WXGA
Display Mode: Normally Black, Transmissive
Active Area: 575.769x323.712 mm
Display Colors: 16.7M (8-bit)
Frequency: 60Hz
Lamp Type: CCFL