REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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Tuesday 15 September 2020

REPAIRING / SERVICING TV SAMSUNG UE55RU7400U

Technical description and composition of the SAMSUNG UE55RU7400U TV, panel type and modules used. The composition of the modules.
SAMSUNG LED
Model: UE55RU7400U
Panel: LSF550FN09
LED driver (backlight): integrated into PSU
PWM LED driver: so-16
MOSFET LED driver: TO-252
Power Supply (PSU): BN44-00932Q L55E7-RMS
PWM Power: PFC (so-8), PWM (so-16)
MOSFET Power: TO-252, TO-220F
MainBoard: BN41-02703A BN94-14489L
IC MainBoard: CPU, eMMC, DRAM, AUDIO, DC / DC
Tuner: BN40-00331B
UE55RU7400U Specifications
SAMSUNG UE55RU7400U
General recommendations for TV LCD LED repair
Possible manifestations of defects
- TV SAMSUNG UE55RU7400U does not turn on and does not show any signs of operability at all. No response to the remote control and front panel control buttons.
In such cases, the BN44-00932Q power supply usually fails. It is necessary to make sure that its output voltages are present and, if they are completely absent, check the power switches (TO-252, TO-220F) and rectifier diodes 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 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 controller, in frequency setting or damper circuits, as well as in negative feedback stabilization. PWM microcircuits (PWM) PFC, PWM are usually checked by replacing them with new ones, or knowingly working.
- There is no image, the screen is black, there is sound, sometimes you can see barely noticeable outlines of the image in the ambient light of the screen.
Usually, in such cases, there is no backlighting of the LED panel (matrix). The reason can be found in the malfunction of the LEDs, in the violation of the contact connections of the LED strips, or in the provision of their power supply (LED driver).
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 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 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 BN41-02703A motherboard should begin with checking the stabilizers and power converters required 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 need to check the serviceability of its elements - CPU, eMMC, DRAM, AUDIO, DC / DC. Defective components must be replaced.
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 in accordance with the ratings of the supply voltages at the BN40-00331B tuner terminals. 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.
Once again, I remind TV users: you should not try to repair yourself without the appropriate knowledge, experience and the necessary qualifications! Trust the repair to professionals with sufficient experience in the field of electronic repair.
Additional MainBoard Repair
The appearance of the MainBoard BN41-02703A is shown in the figure below:
BN41-02703A
External view of the power supply
Main features of the SAMSUNG UE55RU7400U device:
Installed matrix (LED panel) LSF550FN09.
To power the backlight LEDs, a converter combined with a power supply is used, controlled by a so-16 PWM controller. TO-252 switches are used as power elements of the LED driver.
The formation of the necessary supply voltages for all nodes of the SAMSUNG UE55RU7400U TV is carried out by the BN44-00932Q power module, or its analogs using PFC (so-8), PWM (so-16) chips and power switches of the TO-252, TO-220F type.
MainBoard - the main board (motherboard) is a BN41-02703A module using CPU, eMMC, DRAM, AUDIO, DC / DC and others.
Tuner BN40-00331B provides reception of television programs and tuning to channels.


 There are files to download for the UE55RU7400UXRU model from the manufacturer:Latest software updates, firmware (latest firmwares):File type File name Version Date SizeUpdate file (USB) T-MSLDEUC.zip 1360.9 07/14/2020 1281.07 MbUpdate instruction 2019_TV_Firmware_Upgrade_Instruction_T-MSLDEUC.pdf 1.0 16.06.2020 0.49 MbUpdate file (USB) T-MSLDEUC_1360.9.exe 1360.9 14.07.2020 1280.78 MbUpdate file (USB) T-MSLDEUC_1360.9_RU.exe 1360.9 14.07.2020 1280.78 MbUser Manuals and Instructions:File type File name Version Date SizeUser manual BN68-09493G-00_URU7400G_EN_L02_190215.1.pdf 00 03/15/2019 0.81 MbBrief instructions BN68-09508A-00_QSG_URU7400G_CIS_190213.0.pdf 00 03/15/2019 0.56 MbPDF manual MUSDVBEUR-3.0.0_EM_MUSE_EU_ENG_190820.0.pdf 3.0.0 24.10.2019 22.14 MbPDF instruction MUSDVBEUR-3.0.0_EM_MUSE_EU_RUS_190820.0.pdf 3.0.0 24.10.2019 22.12 MbFiles can be downloaded from the manufacturer's website for the UE55RU7400UXRU model.

SAMSUNG UE55RU7400U TV with LCD LSF550FN09, diagonal size 54.6 "(139 cm) 16: 9 format. The display technology of this model is implemented with LED backlighting.
LSF550FN09 sensor and MainBoard BN41-02703A software are capable of realizing images in the highest UHD quality at a resolution of 3840x2160 pixels in 4K UHD, HDR standard. Image processing is performed using modern High Dynamic Range (HDR) technology with an extended range of brightness gradations.
The UE55RU7400U TV is equipped with SMART software, built-in applications and the ability to work on the Internet. The connection to the network can be carried out via Wi-Fi wireless connection. Supported media file formats: MP3, WMA, MPEG4, HEVC (H.265), MKV, JPEG.
Speaker sound system power 20 W (2x10 W) is provided by two speakers. The NICAM stereo audio processing system and the Sound Surround function are used.
Communication with other devices via an external interface is supported by standard input and output connectors: antenna input (RF), AV, component, HDMI x3, USB x2, Ethernet (RJ-45), Bluetooth, Wi-Fi 802.11ac, Miracast.
The digital tuner can receive TV channels in the DVB-T MPEG4, DVB-C, DVB-T2, DVB-S2 standards.
The power consumed when operating from the mains is 145 W. BN44-00932Q power supply.
Dimensions: with stand 1239x800x361 mm, without stand 1239x714x59 mm.
TV weight: with stand: 19.7 kg, without stand: 17.2 kg.
Attention! Panel LSF550FN09 LED-TV SAMSUNG UE55RU7400U 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.

Posted By: FRANK at 06:36
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