Monday, 1 February 2021

REPAIRING / SERVICING TV TELEFUNKEN TF-LED50S84T2SU

Technical description and composition of the TELEFUNKEN TF-LED50S84T2SU TV, panel type and modules used. The composition of the modules.

TELEFUNKEN LED
Model: TF-LED50S84T2SU

Chassis / Version: TP.MT5522S.PC822

Panel: CX500DLEDM

T-CON: CV500U1-T01-CB-1

LED driver (backlight): integrated into MainBoard

MOSFET LED driver: TO-252

Power Supply (PSU): integrated into MainBoard

PWM Power: PFC, PWM (SO-16)

MOSFET Power: TO-252

MainBoard: TP.MT5522S.PC822

IC MainBoard: CPU: MT5522ZHOJ, Audio: RDA3118E28B

Tuner: CDT-9NT372-SL50 & SAT

TF-LED50S84T2SU Specifications
TELEFUNKEN TF-LED50S84T2SU
General recommendations for TV LCD LED repair
Possible manifestations of malfunctions

- TELEFUNKEN TF-LED50S84T2SU 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.

A malfunction in such cases should be looked for in the elements of the power source - the mains voltage converter (AC / DC), which is located on the main board MainBoard TP.MT5522S.PC822. Its output voltages should be measured, and if they are absent, check the serviceability of the power switches (TO-252) of the converters and rectifier diodes for the probability of a short circuit.
In case of breakdowns in the secondary circuits of the converter, it can usually work in an emergency mode in a short circuit mode, and with a short circuit in the power elements of the primary circuit, the mains fuse or current sensor in the source of the key is most often cut off.
Breakdown of power switches (MosFet) in switching sources is sometimes caused by malfunctions of other circuit elements, for example, in the circuits supplying the PWM controller, frequency setting or damper, as well as in the circuits of Negative Feedback (OOS) stabilization. PWM controllers (PWM) PFC, PWM (SO-16), if they do not have visible damage to the case and an outright short circuit between the terminals, are usually checked by replacing.

- There is no picture, there is sound, all other TV functions are working. When turned on, the image may sometimes appear for a second.

In such cases, the most likely malfunction of the LED panel backlighting elements. The reason may be in the breakage of the backlight LEDs, in the stabilization of their power supply, or in the violation of the contact connections of the strings connectors.
To check the health of the LED circuit, it is better to use a current source with a maximum voltage of 200V. We do not recommend using any voltage sources for this purpose. You can check each LED separately with a simple Chinese multimeter (powered by 9 volts) in the P-N transition test mode. If you connect the red probe of the multimeter to the anode of the LED, and the black one to its cathode, then the 3-volt LED will light up slightly, and in the opposite direction you can detect the transition of the emergency zener diode. The serviceability of the PN junction of the Zener diode indirectly indicates the serviceability of the LED-a

- The indicator on the front panel blinks, the TV does not turn on in operating mode, does not respond to the remote control.

Repair or diagnostics of the TP.MT5522S.PC822 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). If it is not possible to replace the MB (SSB) board, you must check the serviceability of its elements - CPU: MT5522ZHOJ, Audio: RDA3118E28B. Defective components must be replaced.

If there is no reception of TV channels, but the TV is working properly from external devices, first of all, you need to check the supply voltage of the CDT-9NT372-SL50 & SAT tuner and update the software. I2C communication pulses must be monitored with an oscilloscope.



Remember! Attempts to self-repair the TELEFUNKEN TF-LED50S84T2SU 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   ------------------>   Chassis TP.MT5522S.PC822.




Additional MainBoard Repair

The appearance of the MainBoard TP.MT5522S.PC822 is shown in the figure below:




TP.MT5522S.PC822

Main features of the TELEFUNKEN TF-LED50S84T2SU device:

Installed matrix (LED panel) CX500DLEDM.
Matrix control uses the Timing Controller (T-CON) CV500U1-T01-CB-1.
A converter combined with the main board TP.MT5522S.PC822 is used to power the backlight LEDs. TO-252 switches are used as power elements of the LED driver.
The power module is combined with the MainBoard and is made according to the AC / DC flyback voltage converter using PFC, PWM (SO-16) microcircuits and TO-252 power switches.
MainBoard - the main board (motherboard) is a TP.MT5522S.PC822 module, using CPU chips: MT5522ZHOJ, Audio: RDA3118E28B and others.
The CDT-9NT372-SL50 & SAT tuner provides reception of television programs and tuning to channels.

TELEFUNKEN TF-LED50S84T2SU TV with LCD CX500DLEDM, diagonal size 50 "(127 cm) 16: 9. The brightness of the screen 370 cd / m² is provided by LED backlighting. Contrast, as the ratio of maximum brightness to minimum brightness, is 5000: 1 The technology of manufacturing the screen of this TV model is realized with LED backlighting.
The CX500DLEDM sensor and MainBoard TP.MT5522S.PC822 software realize high quality UHD images at 3840x2160 pixels in 4K UHD standard.
TF-LED50S84T2SU TV has built-in SMART software and pre-installed Android operating system. Internet connection can be made via Wi-Fi wireless connection. Supported media file formats: MP3, WMA, Xvid, DivX, MKV, JPEG.
Speaker power 16 W (2x8 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, VGA, HDMI x3, USB x2, Ethernet (RJ-45), Wi-Fi. A headphone output is provided. The digital tuner is capable of receiving television channels in the DVB-T, DVB-T2, DVB-C, DVB-S, DVB-S2 standards.

A power supply unit is used as part of the MainBoard.

Dimensions: with stand 1120x725x240 mm, without stand 1120x650x85 mm.

TV weight: 12 kg.

Attention! The CX500DLEDM panel of the TELEFUNKEN TF-LED50S84T2SU LED TV is an expensive and unreliable element.
Do not allow any impact on the glass and pressure on the screen surface to avoid damage to the LED panel!
It is also 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.

Once again, I remind users and TV owners. Attempts to repair yourself can have serious negative consequences, up to complete non-repairability.