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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Sunday 22 March 2020

REPAIR / SERVICING TV BBK 28LEM-1003

Technical description and composition of the BBK 28LEM-1003 TV, type of panel and applicable modules. The composition of the modules.
BBK LED
Model: 28LEM-1003 / T2C
Chassis / Version: JUC7.820.00098892
Panel: M280X13-E4-H
LED driver (backlight): integrated into MainBoard
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MOSFET Power: TO-252
MainBoard: JUC7.820.00098892 LS1B
IC MainBoard: Spi Flash: 25Q64BSIG, Ram: SK Hunix H5TQ1G63EFR, Audio: TPA31100D2
Tuner: DT21WN-2A-E
Technical Specifications 28LEM-1003 / T2C
BBK 28LEM-1003
General repair guidelines for TV LCD LED
Possible malfunctions
- The BBK 28LEM-1003 TV does not turn on at all. The control lights do not light or flash. The TV on the remote control and the control panel buttons do not respond.
The malfunction in such cases, first of all, should be sought in the power elements of a switching power supply (IIP) - a network voltage converter (AC / DC), which in this TV model is combined with the MainBoard JUC7.820.00098892 main board. It is then necessary to measure its output voltages and, if they are absent, you should check the power switches (TO-252) and the rectifier diodes of the converters for the probability of a short circuit.
In case of breakdowns in the secondary circuits of the converter, it can usually fail in short circuit mode, and in case of a short circuit in the power elements of the primary circuit, the mains fuse or current sensor at the source of the key most often breaks.
Breakdown of power switches (MosFet) in pulsed sources is sometimes caused by malfunctions of other circuit elements, for example, in circuits supplying a PWM controller, frequency-setting or damper ones, as well as in negative feedback (OOS) stabilization circuits. PWM controllers (PWM) PWM SOT23-6, if they do not have visible damage to the case and open short circuit between the terminals, are usually checked by replacement.
- There is no image, there is sound, it responds to the remote control, the channels are switched. In some cases, the image appears when you turn on and immediately disappears.
The faulty usually in these cases is the backlight matrix (LED-panel). More often the reason for this is the breakdown of the LEDs, or poor contact in the connectors of the strips, less often the LED driver may be malfunctioning.
To check the health in 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 individually with a simple Chinese multimeter (powered by 9 volts) in the P-N-junction test mode. If you connect the red probe of the multimeter to the anode of the LED, and the black 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. A zener diode PN junction indirectly indicates a LED-a
- The indicator on the front panel blinks, the TV does not turn on in the operating mode, it does not respond to the remote control.
Repair or diagnostics of the JUC7.820.00098892 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). When repairing an MB board, you need to check its components Spi Flash: 25Q64BSIG, Ram: SK Hunix H5TQ1G63EFR, Audio: TPA31100D2. Defective items should be replaced. If chips with BGA soldering technology are used, a problem in its implementation is detected by the local heating of the chip.
The malfunction of the tuner DT21WN-2A-E is established after checking the software and all the supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
Owners of the 28LEM-1003 TV are recommended for repairs to contact only qualified specialists with the necessary work experience! Self-repair attempts without the appropriate knowledge and skills can lead to irreversible negative consequences!
FIRMWARE FOR SPI FLASH  ----------->   BBK 28LEM-1003/T2C, Main: JUC7.820.00098892 LS1B, Panel: M280X13-E4-H


 Schematic Diagrams 24 pages of 2013 for models: 19LEM-3082/T2C, 22LEM-3082/FT2C, 24LEM-1004/T2C, 28LEM-1003/T2C, 32LEM-1003/T2C, 32LEM-3081/T2C

The appearance of the MainBoard JUC7.820.00098892 is shown in the figure below:
JUC7.820.00098892
JUC7.820.00098892 can be used in TVs:
BBK 32LEM-1003/T2C (Panel LC320EXN), BBK 28LEM-1003/T2C (Panel M280X13-E4-H), ERISSON 28LEC2300 (Panel 720p HD 1366x768).
Main features of the BBK 28LEM-1003 device:
The matrix (LED panel) M280X13-E4-H is installed.
To power the backlight LEDs, a converter is used, combined with the main board JUC7.820.00098892.
The power module is combined with the MainBoard and is designed according to a flyback AC / DC voltage converter using PWM SOT23-6 microcircuits and TO-252 type power switches.
MainBoard - the main board (motherboard) is a JUC7.820.00098892 module, using Spi Flash chips: 25Q64BSIG, Ram: SK Hunix H5TQ1G63EFR, Audio: TPA31100D2 and others.
Tuner DT21WN-2A-E provides the reception of television programs and tuning to channels.


BBK 28LEM-1003 / T2C LED TV with M280X13-E4-H LCD, 28 "(71 cm) diagonal of 16: 9 format. The required brightness of the screen is 250 cd / m² and LED backlighting is provided. The ratio of maximum brightness to the minimum (contrast) is 3000: 1. This model uses side illumination from Edge LEDs. You can view images in high quality HD at a resolution of 1366x768 pixels in the standard of graphic decomposition 720p (HD Ready). The input high-frequency or video signal can be processed in analog PAL, SECAM, NTSC systems. Digital signal processing and generation takes place in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Supported media file formats: MP3, WMA, MPEG4, MKV, JPEG.
The power of the sound system 10 W (2x5 W) provides two speakers. It uses a NICAM stereo signal processing system and Sound Surround.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x2, VGA, HDMI x3, USB. An output for connecting headphones is provided. To connect a computer or laptop to this TV model, a VGA (D-Sub 15) connector is used on the TV case, this interface supports resolutions: 640x480, 800x600, 1024x768, 1360x768. The digital tuner is capable of receiving television channels in the DVB-T MPEG4, DVB-C MPEG4, DVB-T2 standards.
Overall dimensions: With stand 645x447x165 mm, Without stand 645x396x75 mm.
The mass of the TV: 5.2 kg.
Attention! The BBK 28LEM-1003 / T2C LED TV panel M280X13-E4-H is an expensive and unreliable element.
Avoid any impact on the glass and pressure on the surface of the screen to avoid damage to the LED panel!
It is also unsafe to get liquid on the screen. Sometimes one drop is enough if it flows down the glass onto the cables so that the TV becomes unrepairable.
Posted By: FRANK at 06:42
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