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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Monday 24 August 2020

REPAIRING / SERVICING TV DNS K42A619

Technical description and composition of the DNS K42A619 TV, panel type and modules used. The composition of the modules.
DNS LED
Model: K42A619
Chassis / Version: 35017733
Panel: HA1T683 / V420HJ2-P01 Rev. C1
LED backlight: KL42GT618 35017849, KL42GT618 35017855
T-CON: V420HJ2-XC01
LED driver (backlight): integrated into MainBoard
PWM LED driver: OCP8122A
Power Supply (PSU): integrated into MainBoard
PWM Power: FAN6755W
MOSFET Power: CS8N65
MainBoard: KL42GT618 -CMI-174YTK 35017733
IC MainBoard: CPU: MT8227AAKU, SPI Flash: 25Q32BVSIG, SOUND: STA333W; TDA18273, IT6633E-P
Tuner: Tuner
Specifications K42A619
DNS K42A619
General recommendations for TV LCD LED repair
Possible manifestations of malfunctions
- DNS K42A619 does not turn on, LEDs on the front panel are off or flashing. The TV does not respond to the control buttons and the remote control.
A malfunction in such cases, first of all, should be looked for in the power elements of a switching power supply (SMPS) - a mains voltage converter (AC / DC), which in this TV model is combined with the MainBoard KL42GT618 main board. It is necessary to measure its secondary output voltages, and if they are absent, check the power switches (CS8N65) and rectifier diodes in the converters for a short circuit.
In case of any breakdowns in the secondary circuits, the converter can operate in an emergency mode of a short circuit, and with a short circuit in the power elements of the primary circuit, the mains fuse or the current sensor at the source of the key often breaks off.
The 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 controllers (PWM) FAN6755W, if they do not have visible damage to the case and an outright short circuit between the pins, are usually checked by replacing.
- There is no picture, but there is sound and reaction to commands from the remote control. Or the image appears immediately after switching on and disappears.
A malfunction is usually in these cases most likely in the backlight units of the display matrix. The reason for this may be an open circuit in the LED circuit, or a problem in stabilizing their power supply.
To identify an open circuit in the LED lines without disassembling the panel, a current source is required. It is impossible to open the junctions connected in series with a simple multimeter; a voltage of several tens of volts is required.
- 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 KL42GT618 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). Sometimes it is necessary to check or replace (if necessary) elements of the MainBoard - CPU: MT8227AAKU, SPI Flash: 25Q32BVSIG, SOUND: STA333W; TDA18273, IT6633E-P. In cases where a BGA processor is used, its malfunction is usually detected by a local warm-up method.
If there is no reception of TV channels, but the TV is working properly from external devices, first of all, you need to check the Tuner power supply voltage and update the software. I2C communication pulses must be monitored with an oscilloscope.
Owners and users of the DNS K42A619 TV should remember that self-repair without special knowledge, skills and qualifications may be fraught with negative consequences that can lead to the complete non-repairability of the device!
DOWNLOAD FIRMWARE FOR SPI FLASH  ----------->   DNS K42A619, Main: KL42GT618 -CMI-174YTK 35017733, Panel: HA1T683 / V420HJ2-P01 Rev.C1

 The appearance of the MainBoard KL42GT618 is shown in the figure below:
KL42GT618
Main features of DNS K42A619 device:
Installed matrix (LED-panel) HA1T683 / V420HJ2-P01 Rev. C1.
Matrix control uses Timing Controller (T-CON) V420HJ2-XC01.
To power the backlight LEDs, a converter is used, combined with the main board KL42GT618, controlled by the OCP8122A PWM controller.
The power module is combined with the MainBoard and is made according to the AC / DC flyback voltage converter using FAN6755W microcircuits and power switches of the CS8N65 type.
MainBoard - the main board (motherboard) is a KL42GT618 module, using CPU chips: MT8227AAKU, SPI Flash: 25Q32BVSIG, SOUND: STA333W; TDA18273, IT6633E-P and others.
Tuner Tuner provides reception of television programs and tuning to channels.
DNS TV K42A619 with LCD HA1T683, diagonal 42 "(107 cm) in 16: 9 format. The required screen brightness of 320 cd / m² is provided by LED backlighting. Contrast - the ratio of maximum brightness to minimum is 5000: 1. In LCD -panel uses direct backlighting of pixels with LEDs in the back - Direct LED.
The HA1T683 / V420HJ2-P01 Rev. C1 matrix and the MainBoard KL42GT618 software provide viewing of broadcasts and movies in high quality HD at a resolution of 1920x1080 pixels in graphics resolution at 1080p (Full HD). The input high-frequency or video signal is decoded in analog systems PAL, SECAM, NTSC. Graphic processing and formation of a digital signal occurs in the standards 480i, 480p, 576i, 576p, 720p, 1080i, 1080p. Supported media file formats: MP3, MPEG4, DivX, MKV, JPEG.
Speaker power 24 W (2x12 W) is provided by two speakers. The NICAM STEREO audio processing system is used.
External interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x2, component, SCART, VGA, HDMI x3, USB. A headphone output is provided. To connect a computer or laptop to this TV model, a VGA (D-Sub 15) connector on the TV case is used, this interface supports resolutions: 640x480, 800x600, 1024x768, 1360x768, 1920x1080.
The power consumed by the TV operating in mains mode is 120 watts. MainBoard power supply.
Dimensions: With stand 955x626x241 mm, Without stand 955x566x81 mm.
TV weight: 12 kg.
Attention! The HA1T683 / V420HJ2-P01 Rev. C1 panel of the DNS K42A619 LED TV 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 05:53
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