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 21 April 2020

REPAIR / SERVICING TV DEXP U40B9000H

Technical description and composition of the DEXP U40B9000H TV, type of panel and applicable modules. The composition of the modules.
DEXP LED
Model: U40B9000H
Chassis / Version: RSAG7.820.6135
Panel: V400DK1-QS1
LED backlight: LM41-00105A SAMSUNG_2014CHI396_3228_10_REV1.0_140911
T-CON: 6201b000l3000
LED driver (backlight): integrated into PSU; 195mA
PWM LED driver: LX27901
Power Supply (PSU): RSAG7.820.5687 / ROH HLL-4855WP
PWM Power: NCP1271, NCP1608
MOSFET Power: 10N60, 8N65
MainBoard: RSAG7.820.6135 / ROH
IC MainBoard: CPU: MT5657MCEJ
Tuner: HFT-96S1 / W116H1
Technical Specifications U40B9000H
DEXP U40B9000H
General repair guidelines for TV LCD LED
Possible malfunctions
- The DEXP U40B9000H does not turn on. There are no signs of operability. The indicators on the front panel do not light or flash, the TV does not respond to the remote control and control buttons.
In such cases, the fault should be sought first in the RSAG7.820.5687 power supply module. It is necessary to measure its output voltages, and in case of their absence (full or partial), it is necessary to check the serviceability of power switches (10N60, 8N65) of converters and rectifier diodes for the presence of a possible short circuit.
In case of diode breakdowns in the secondary circuits, the converter can operate in emergency short-circuit mode without output voltages, and during short circuit in the power elements of the primary circuit, the mains fuse and / or current sensor at the source of the key usually breaks.
The breakdown of Mos-Fet keys used in pulsed sources is often caused by malfunctions of other elements, for example, in the power supply circuit of a PWM controller, in frequency-setting or damping circuits, as well as in Negative Stabilization Feedback. PWM microcircuits NCP1271, NCP1608 are usually checked by replacing with new, or obviously working.
- There is no image, but there is sound and reaction to the remote control. Or for a second, the image may appear immediately after switching on.
The most likely in these cases is a malfunction of the LED backlight. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
When trying to detect a break in the LED lines, it should be taken into account that it is difficult to do this without disassembling the panel. For example, a current source is needed to open PN junctions connected in series.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the RSAG7.820.6135 motherboard should begin by checking the stabilizers and power converters needed to power the microcircuits and matrix. If necessary, update or replace the software (software). If it is not possible to replace the MB (SSB) card, you need to check the health of its elements - CPU: MT5657MCEJ. Defective components should be replaced.
Before changing the HFT-96S1 / W116H1 tuner, if it is not possible to tune to television channels, make sure that there are supply voltages that must be measured at the corresponding tuner pins and check the software for correctness. The pulses of the data exchange of the tuner with the processor can be controlled by an oscilloscope
Attention to users! Self-repair of a DEXP U40B9000H TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!




The appearance of the MainBoard RSAG7.820.6135 is shown in the figure below:
RSAG7.820.6135
The appearance of the power supply
Main features of the DEXP U40B9000H device:
Installed matrix (LED-panel) V400DK1-QS1.
The matrix control uses the Timing Controller (T-CON) 6201b000l3000.
To power the backlight LEDs, a converter is used, combined with the power supply, controlled by the LX27901 PWM controller.
The necessary supply voltages for all nodes of the DEXP U40B9000H TV are generated by the RSAG7.820.5687 power module or its analogs using NCP1271, NCP1608 microcircuits and 10N60, 8N65 type power switches.
MainBoard - the main board (motherboard) is an RSAG7.820.6135 module, using CPU chips: MT5657MCEJ and others.
The HFT-96S1 / W116H1 tuner provides TV reception and channel tuning.
DEXP U40B9000H TV with V400DK1-QS1 LCD, 40 "(102 cm) diagonal size of 16: 9 format. The required screen brightness of 300 cd / m² is provided by LED backlighting. Contrast - the ratio of maximum brightness to minimum is 4000: 1. The LCD panel uses direct pixel illumination with rear LEDs - Direct LED. You can watch movies and images in the highest quality UHD at a resolution of 3840x2160 pixels in the 4K UHD standard.
The U40B9000H is equipped with SMART software, embedded applications and the ability to work on the Internet. Connecting to the Internet can be done via Wi-Fi. The input high-frequency or video signal is decoded in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation occurs in standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Supported media file formats: MP3, WMA, MPEG4, HEVC (H.265), MKV, JPEG.
The power of the sound system 14 W (2x7 W) provide two speakers. The audio processing system NICAM STEREO is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, component, HDMI x4, USB x2, Ethernet (RJ-45), Wi-Fi. 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 DVB-T MPEG4, DVB-C, DVB-T2 standards.
Overall dimensions: with stand 900x550x195 mm, without stand 900x510x83 mm.
TV Weight: with stand: 8.8 kg, without stand: 8.5 kg.
Attention! The panel V400DK1-QS1 of an LED-TV DEXP U40B9000H 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 06:51
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