Monday 10 August 2020

REPAIRING / SERVICING TV TELEFUNKEN TF-LED32S20T2

Technical description and composition of the TELEFUNKEN TF-LED32S20T2 TV, panel type and modules used. The composition of the modules.
TELEFUNKEN LED
Model: TF-LED32S20T2
Chassis / Version: TP.MS3463S.PB782
Panel: ST3151A05-8 Ver.2.5 LVW320CSDX
T-CON: MT3151A05-5-XC-9
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP3398A
MOSFET LED driver: ME15N10-G
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6 LD7536R
MOSFET Power: 7N65
MainBoard: TP.MS3463S.PB782
IC MainBoard: SPI FLASH: 25Q64, AUDIO: TPA3110LD2
Tuner: XF-3SDT-H
TF-LED32S20T2 Specifications
TELEFUNKEN TF-LED32S20T2
General recommendations for TV LCD LED repair
Possible manifestations of malfunctions
- TELEFUNKEN LED32S20T2 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.
First of all, in such cases, you should make sure that the common switching power supply (SMPS) - the AC / DC voltage converter of the mains voltage - is working. All source elements in this TV model are located on the MainBoard TP.MS3463S.PB782. Then we recommend measuring its output voltages and, if they are absent, check the serviceability of the power switches (7N65) and rectifier diodes of the converters for a possible short circuit.
In case of breakdowns of semiconductors in the secondary circuits of any converter, as a rule, it can operate in an emergency mode of short circuit without output voltages, and with a short circuit in the elements of the primary circuit, the mains fuse most often breaks off immediately and, less often, the current sensor in the source of the key.
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 regulators (PWM) PWM SOT23-6 LD7536R, if they have no visible damage to the case and an outright short circuit between the pins, are usually checked by replacing.
- 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.
Usually, in such cases, a malfunction is detected in the nodes of the backlight of the LED panel. The reason for this may be an open circuit in the LED circuit, or a problem in stabilizing their power supply.
Without a special current source, it is impossible to check the line of LEDs connected in series, and it is unsafe for them to use any voltage sources above 12V for this purpose. Then all that remains is to open the panel and check each LED separately. Typically, Chinese multimeters with a 9V power supply lightly light up one 3-volt LED, if you connect the probes to it in the forward direction, the red probe to the anode, and the black one to the cathode. For dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of LED health. In the event of a malfunction of the LED, its zener diode will either be cut off or broken into the K / Z.
- The TV does not turn on, the indicator signals standby or operating mode, or blinks.
Repair or diagnostics of the TP.MS3463S.PB782 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 the TV operates normally from external devices, but does not tune to TV channels, the SPI FLASH: 25Q64, AUDIO: TPA3110LD2 tuner may malfunction. In such cases, first of all, you should make sure that the supply voltage is present at its corresponding terminals. It is also necessary to make sure that the data exchange between the tuner and the processor is possible via the I2C bus. Sometimes the reason for the inoperability of the tuner may be a software failure.
Owners and users of the TELEFUNKEN LED32S20T2 TV should remember that self-repair without special knowledge, skills and qualifications can be fraught with negative consequences that can lead to the complete non-repairability of the device!

To reduce the backlight current, you should proportionally increase the total resistance of the resistors relative to the case at the ISET pin of the MP3398A controller. ISET (Current Setting) - Pin 8 in SOIC-20 package or Pin 6 in SOIC-16 package.
Additional MainBoard Repair
The appearance of MainBoard TP.MS3463S.PB782 is shown in the figure below:
TP.MS3463S.PB782
TP.MS3463S.PB782 can be used in TVs:
DAEWOO L32S645VTE (Panel ST3151A05-8 VER.2.4), TELEFUNKEN TF-LED32S20T2 (Panel ST3151A05-8 Ver.2.5 LVW320CSDX), TELEFUNKEN TF-LED32S17T2 (Panel ST3151A05-8).
Main features of the TELEFUNKEN TF-LED32S20T2 device:
Installed matrix (LED-panel) ST3151A05-8 Ver.2.5 LVW320CSDX.
Matrix control uses the Timing Controller (T-CON) MT3151A05-5-XC-9.
To power the backlight LEDs, a converter combined with the main board TP.MS3463S.PB782 is used, controlled by the PWM controller MP3398A. The keys of the ME15N10-G type 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 converter circuit using PWM SOT23-6 LD7536R microcircuits and power switches of the 7N65 type.
MainBoard - the main board (motherboard) is a TP.MS3463S.PB782 module, using SPI FLASH: 25Q64, AUDIO: TPA3110LD2 and others.
Tuner XF-3SDT-H provides reception of television programs and tuning to channels.

TV TELEFUNKEN TF-LED32S20T2 with LCD ST3151A05-8, diagonal size 31.5 "(80 cm) 16: 9. Screen brightness 270 cd / m² is provided by LED backlight. Contrast, as the ratio of maximum brightness to minimum, is 3000 : 1. The technology of production of the screen of this TV model is realized with LED backlighting. It is possible to view images in high quality HD at a resolution of 1366x768 pixels in the standard of graphic decomposition 720p (HD Ready). Supported multimedia file formats: MP3, MPEG4, Xvid, DivX, MKV , JPEG.
The power of the acoustic system of sound is 10 W (2x5 W), 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, component, SCART, VGA, HDMI x2, USB. A headphone output is provided.
The digital tuner is capable of receiving television channels in the DVB-T, DVB-C, DVB-T2 standards.
Overall dimensions: 734x480x177 mm.
TV weight: 5 kg.
Attention! Panel ST3151A05-8 Ver.2.5 LVW320CSDX LED TV TELEFUNKEN TF-LED32S20T2 is an expensive and unreliable element.
Do not allow any impacts 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 non-repairable.