Sunday 9 August 2020

REPAIRING / SERVICING TV TELEFUNKEN TF-LED43S81T2S

Technical description and composition of the TELEFUNKEN TF-LED43S81T2S TV, panel type and modules used. The composition of the modules.
TELEFUNKEN LED
Model: TF-LED43S81T2S
Chassis / Version: CV338H-U42
Panel: CX430DLEDM
LED backlight: MS-L1143
T-CON: ST4251B01-1-XC-7
LED driver (backlight): integrated into MainBoard
PWM LED driver: BIT3267
MOSFET LED driver: AOD4454
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MOSFET Power: N-FET 7N60 TO-252
MainBoard: CV338H-U42
IC MainBoard: CPU: MSD6A338, SPI Flash: 25Q16
Tuner: R842 Rafael Micro
TF-LED43S81T2S Specifications
TELEFUNKEN TF-LED43S81T2S
General recommendations for TV LCD LED repair
Possible manifestations of defects
- TELEFUNKEN TF-LED43S81T2S TV does not turn on at all. No response to the remote control and front panel control buttons. Indicator lamps do not light up or flash.
In such cases, the common power source is often faulty - the AC / DC converter of the mains voltage, which is combined with the elements of the CV338H-U42 main board. In the absence of the necessary supply voltages in the secondary circuits of the converters, it is necessary to check the power switches (N-FET 7N60 TO-252) and rectifier diodes for possible partial or complete breakdown.
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 Mos-Fet switches used in switching power supplies is often caused by malfunctions of other elements, for example, in the power supply circuit of a PWM regulator, in frequency-setting or damper circuits, as well as in negative feedback stabilization. PWM microcircuits (PWM) PWM SOT23-6 are usually checked by replacing them with new ones, or knowingly working.
- There is no picture, but there is sound and reaction to the remote control. Or the image may appear for a second immediately after switching on.
As a rule, in this case, the backlight of the LED panel is faulty. The reason can sometimes be in the power supply of the LEDs, but more often in their malfunction (breakdown or open circuit), sometimes in the violation of the contact connections of the LED strips.
Without a special current source, it is impossible to check the line of series-connected LEDs, and it is unsafe for them to use any voltage sources over 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 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 CV338H-U42 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). Often the MB (SSB) board needs to be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU: MSD6A338, SPI Flash: 25Q16 and replace the failed chips with new ones. Some malfunctions may be associated with the use of BGA soldering technologies in modern Main Board. Typically, such defects are detected by local heating of the chip.
If the TV operates normally from external devices, but does not tune to TV channels, the R842 Rafael Micro tuner may be faulty. 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 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 to users! Self-repair of the TELEFUNKEN TF-LED43S81T2S TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!


DOWNLOAD SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    Chassis CV338H-T42

 MainBoard CV338H-U42 is shown in the figure below:
CV338H-U42
Main features of the TELEFUNKEN TF-LED43S81T2S device:
Installed matrix (LED panel) CX430DLEDM.
Matrix control uses Timing Controller (T-CON) ST4251B01-1-XC-7.
To power the backlight LEDs, a converter combined with the CV338H-U42 main board is used, controlled by the BIT3267 PWM controller. The keys of the AOD4454 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 voltage converter circuit using PWM SOT23-6 chips and N-FET 7N60 TO-252 power switches.
MainBoard - the main board (motherboard) is a CV338H-U42 module, using CPU chips: MSD6A338, SPI Flash: 25Q16 and others.
Tuner R842 Rafael Micro provides reception of television programs and tuning to channels.


 

 

PWM SMPS in SOT-23-6, SOT-26, TSOP-6 packages

In the circuitry of modern switching power supplies (SMPS), PWM controllers made in small-sized planar packages with six terminals have gained wide popularity. The enclosure type designation can be SOT-23-6, SOT-23-6L, SOT-26, TSOP-6, SSOT-6. The appearance and arrangement of the pins are shown in the figure below. In this case, the code marking LD7530A is shown on the left fragment of the picture.


 

 Pin assignment:
1 - GND. (Common wire).
2 - FB. (FeedBack - Feedback). Input for controlling the duration of pulses with a signal from the output voltage. Sometimes it can be labeled COMP (input comparator).
3 - RI / RT / CT / COMP / NC - Depending on the type of microcircuit, it can be used for a frequency-setting RC circuit (RI / RT / CT), or for organizing protection, as an input of a PWM trip comparator at a threshold value at its input, specified in the document. In some types of microcircuits, this input may not be used in any way (NC - No Connect).
4 - SENSE, otherwise CS (Current Sense) - Input from the current sensor at the source of the key.
5 - VCC - Input voltage supply and start of the microcircuit.
6 - OUT (GATE) - Output for controlling the gate (Gate) of the key.

Functionally, these regulators work on the principle of the previously popular xx384x PWM microcircuits, which have proven themselves well in terms of reliability and stability.

Some difficulties often arise when replacing or choosing an analog for such PWM regulators due to the use of code markings in the designation of the type of microcircuits. The situation is complicated by a large number of component manufacturers who do not always provide documentation to the mass access, just as not all manufacturers of finished devices supply repair service centers with diagrams, so repairmen often have to study real circuit solutions by installed components and wiring connections directly on the board.

In practice, PWM microcircuits and the marking code EAxxx and Eaxxx are often found. Official documentation for them was not found in the public domain, but discussions on the forums and pieces of pictures from PDF from System General, which publishes them as SG6848T and SG6848T2, have survived. The drawing is here placed left .


 

For the attention of the masters, here below are PDF datasheet tables compiled from information available on the Internet and PDF documents for the selection of analogues types when replacing the most common six-legged planar PWM with pinout pins: pin1 - GND, pin2 - FB (COMP), pin4 - Sense, pin5 - Vcc, pin6 - OUT ...
Their main difference is the application and purpose of pin 3. 

 

NamePart NumberFabricantMarking
SG6849SG684965TZFairchild / ON SemiBBxx
SG6849SG6849-65T, SG6849-65TZSystem GeneralMBxx EBxx
SGP400SGP400TZ System General AAKxx

 

 PWM controllers (PWM) with a 95-100 kOhm resistor on pin 3.

When applying the PWM listed below, the frequency should be set with the RT (RI) resistor from pin 3 to ground. Usually its nominal value is chosen 95-100 kOhm for a frequency of 65-100 KHz. For more details, see the here below attached documentation. PDF files are packed in RAR.

 

NamePart NumberFabricantMarking
AP3103AAP3103AKTR-G1Diodes IncorporatedGHL
AP8263AP8263E6R, A8263E6VRAiT SemiconductorS1xx
AT3263AT3263S6ATC Technology3263
CR6848CR6848SChip-Rail848H16
CR6850CR6850SChip-Rail850xx
CR6851CR6851SChip-Rail851xx
FAN6602RFAN6602RM6XFairchild / ON SemiACCxx
FS6830FS6830FirstSemi
GR8830GR8830CGGrenergy30xx
GR8836GR8836C, GR8836CGGrenergy36xx
H6849H6849NFHI-SINCERITY
H6850H6850NFHI-SINCERITY
HT2263HT2263MPHOT-CHIP63xxx
KP201
Kiwi Instruments
LD5530LD5530GL LD5530RLeadtrandxxt30 xxt30R
LD7531LD7531GL, LD7531PLLeadtrendxxP31
LD7531ALD7531AGLLeadtrendxxP31A
LD7535/ALD7535BL, LD7535GL, LD7535ABL, LD7535AGLLeadtrendxxP35-xxx35A
LD7550LD7550BL, LD7550ILLeadtrendxxP50
LD7550BLD7550BBL, LD7550BILLeadtrend xxP50B
LD7551LD7551BL/ILLeadtrendxxP51
LD7551CLD7551CGLLeadtrendxxP51C
NX1049XN1049TPXian-Innuovo49xxx
OB2262OB2262MPOn-Bright-Electronics62xx
OB2263OB2263MPOn-Bright-Electronics63xx
PT4201PT4201E23FPowtech4201
R7731R7731GE/PERichtek0Q=
R7731AR7731AGERichtekIDP=xx
SD4870SD4870TRSilan Microelectronics4870
SF1530SF1530LGTSiFirst30xxx
SG5701SG5701TZSystem GeneralAAExx
SG6848SG6848T, SG6848T1, SG6848TZ1, SG6848T2Fairchild / ON SemiAAHxx EAxxx
SG6858SG6858TZFairchild / ON SemiAAIxx
SG6859ASG6859ATZ, SG6859ATYFairchild / ON SemiAAJFxx
SG6859SG6859TZFairchild / ON SemiAAJMxx
SG6860SG6860TYFairchildAAQxx
SP6850SP6850S26RGSporton Lab850xx
SP6853SP6853S26RGB, SP6853S26RGSporton Lab853xx
SW2263SW2263MPSamWin
UC3863/GUC3863G-AG6-RUnisonic Technologies CoU863 U863G
XN1049XN1049, XN1049TPInnuovo Microelectronics49 xxx

 

 PWM controllers that use pin 3 differently.

When using the following PWM (PWM controllers), you should pay attention to pin 3, which can be used to organize protection - thermal or from overvoltage of the input voltage.
The frequency can be fixed at 65kHz, or set by the value of the capacitor at pin 3.
When replacing any microcircuits with analogs, carefully study the documentation. PDF files are packed in a RAR archive.

 

NamePart NumberFabricantMarking
AP3105/V/L/RAP3105KTR-G1, AP3105VKTR-G1, AP3105LKTR-G1, AP3105RKTR-G1Diodes IncorporatedGHN GHO GHP GHQ
AP3105NA/NV/NL/NRAP3105NAKTR-G1, AP3105NVKTR-G1, AP3105NLKTR-G1, AP3105NRKTR-G1Diodes IncorporatedGKN GKO GKP GKQ
AP3125A/V/L/RAP3125AKTR-G1, AP3125VKTR-G1, AP3125LKTR-G1, AP3125RKTR-G1Diodes IncorporatedGLS GLU GNB GNC
AP3125BAP3125BKTR-G1Diodes IncorporatedGLV
AP3125HA/HBAP3125HAKTR-G1, AP3125HBKTR-G1Diodes IncorporatedGNP GNQ
AP31261AP31261KTR-G1Diodes IncorporatedGPE
AP3127/HAP3127KTR-G1, AP3127HKTR-G1Diodes IncorporatedGPH GSH
AP3301AP3301K6TR-G1Diodes IncorporatedGTC
FAN6862FAN6862TYFairchild / ON SemiABDxx
FAN6863FAN6863TY, FAN6863LTY, FAN6863RTYFairchild / ON SemiABRxx
HT2273HT2273TPHOT-CHIP73xxx
LD7510/JLD7510GL, LD7510JGLLeadtrendxxP10 xxP10J
LD7530/ALD7530PL, LD7530GL, LD7530APL, LD7530AGLLeadtrendxxP30 xxxP30A
LD7532LD7532GLLeadtrendxxP32
LD7532ALD7532AGLLeadtrendxxP32A
LD7532HLD7532HGLLeadtrendxxP32H
LD7533LD7533GLLeadtrendxxP33
LD7536LD7536GLLeadtrendxxP36
LD7536RLD7536RGLLeadtrendxxP36R
LD7537RLD7537RGLLeadtrendxxP37R
LD7539C GLLD7539C GLLeadtrendxxP39C
ME8204ME8204M6GMicrOneME8204xx
NCP1250NCP1250ASN65T1G, NCP1250BSN65T1G, NCP1250ASN100T1G, NCP1250BSN100T1GON Semiconductor25xxxx
NCP1251NCP1251ASN65T1G, NCP1251BSN65T1G, NCP1251ASN100T1G, NCP1251BSN100T1GON Semiconductor5xxxxx
OB2273OB2273MPOn-Bright-Electronics73xx
R7735R7735AGE, R7735HGE, R7735GGE, R7735RGE, R7735LGERichtek
UC3873/GUC3873-AG6-R, UC3873G-AG6-RUnisonic TechnologiesU873 U873G

 

 

 

TELEFUNKEN TF-LED43S81T2S LCD TV, 42.5 "(108 cm) diagonal, 16: 9 format. The brightness of the screen is 280 cd / m² provided by LED backlighting. Contrast, as the ratio of maximum brightness to minimum, is 3000: 1. The technology of manufacturing the screen of this TV model is realized with LED backlighting.The design and technical capabilities of the TV provide viewing of broadcasts and films in high quality HD at a resolution of 1920x1080 pixels in graphic resolution according to the standard 1080p (Full HD).
TF-LED43S81T2S 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, MPEG4, Xvid, DivX, MKV, JPEG.
Speaker power 12 W (2x6 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, component, 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 MPEG4, DVB-C, DVB-T2 standards.
Dimensions: with stand 968x612x219 mm, without stand 968x566x80 mm.
TV weight: 7.2 kg.
Attention! Panel LED TV TELEFUNKEN TF-LED43S81T2S 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.