Technical description and composition of the DNS K55D709 TV, panel type and modules used. The composition of the modules.DNS LED
Model: K55D709
Chassis / Version: 35017069
Panel: LC550EUN (PE) (F1)
LED backlight: EDGE LED
T-CON: 6870C-0401C
LED driver (backlight): 6917L-0104A 3PHCC20003F-H
PWM LED driver: iW7018-0, AP3041M-G1
MOSFET LED driver: MBR20150CT, FDD86252
Power Supply (PSU): KPS-L110C3 34008454
PWM Power: FSL206MR, FAN7930, LM358L
MOSFET Power: UK3568L
MainBoard: 35017069 KDL55MS709AD-L-P1L
IC MainBoard: Spi Flash: GD25Q64
Tuner: NoName
Control: IR: 35016471
Specifications K55D709
DNS K55D709
General recommendations for TV LCD LED repair
Possible manifestations of defects
- DNS K55D709 TV does not turn on. There are no signs of operability. The indicators on the front panel do not light or blink, the TV does not respond to the remote control and control buttons.
With similar manifestations, in some cases, the KPS-L110C3 power supply module is faulty. Its output voltages should be measured and, if they are absent, check the power switches (UK3568L) and rectifier diodes for the probability of a short circuit in the converters.
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 in the source of the key is often cut off.
Mos-Fet power switches used in switching power supplies sometimes fail due to a malfunction of any other elements that can disable it in the key mode, or create an excess of the maximum permissible key parameters. These can be elements supplying a PWM regulator, frequency setting or damper circuits, or elements of negative feedback in the stabilization circuit. PWM controllers FSL206MR, FAN7930, LM358L, in the absence of visible damage or outright short circuits between the terminals, are checked by replacing them with new ones, or known to be working properly.
- There is no picture, but there is sound and reaction to the remote control. Or, for a second, the image may appear immediately after switching on.
The malfunction in most of these cases is found in the nodes and elements of the LED panel backlight. The reason may be both in the power supply of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
When diagnosing, it must be borne in mind that it is impossible to check for an open in the circuit of the LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally a current source. By opening the panel, you can check each LED separately. Typically, Chinese multimeters will lightly light one 3-volt LED if you connect the probes to it in the forward direction. 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 motherboard 35017069 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 must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair it, you should check its elements - Spi Flash: GD25Q64 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 you suspect a malfunction of the NoName tuner, first of all, you need to make sure that the software is correct, as well as the presence of the necessary levels of supply voltages and pulses of data exchange with the processor via the I2C bus on the corresponding terminals of the tuner.
Owners of the K55D709 TV are recommended to contact only qualified specialists with the necessary work experience for repair! Attempts to repair yourself without the appropriate knowledge and skills can lead to irreversible negative consequences!
Additional MainBoard RepairThe appearance of MainBoard 35017069 is shown in the figure below:
35017069
External view of the power supply
Key features of the DNS K55D709 device:
The matrix (LED panel) LC550EUN (PE) (F1) is installed.
Matrix control uses the Timing Controller (T-CON) 6870C-0401C.
The LED driver 6917L-0104A is used to power the backlight LEDs, it is controlled by the PWM controller iW7018-0, AP3041M-G1. The keys of the MBR20150CT, FDD86252 type are used as power elements of the LED driver.
The formation of the necessary supply voltages for all nodes of the DNS K55D709 TV is carried out by the KPS-L110C3 power module, or its analogs using FSL206MR, FAN7930, LM358L microcircuits and UK3568L power switches.
MainBoard - the main board (motherboard) is a 35017069 module, using Spi Flash chips: GD25Q64 and others.
Tuner NoName provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC550EUN-PEF1
Type: a-Si TFT-LCD, Panel
Diagonal size: 55 inch
Resolution: 1920x1080, FHD
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 1209.6x680.4 mm
Surface: Antiglare (Haze 1%), Hard coating (2H)
Brightness: 360 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6 (G to G)
Frequency: 60Hz
Lamp Type: WLED Embedded (LED Driver)
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V
DNS TV K55D709 with LCD LC550EUN, diagonal 55 "(140 cm) in 16: 9 format. Necessary screen brightness of 300 cd / m² is provided by LED backlighting. Contrast - the ratio of maximum brightness to minimum brightness is 2000: 1. the model uses a panel with an edge arrangement of backlight LEDs - Edge LED.
There is support for 3D images using passive polarization technology.
The LC550EUN (PE) (F1) matrix and MainBoard KDL55MS709AD-L-P1L 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 480i, 480p, 576i, 576p, 720p, 1080i, 1080p standards. Supported media file formats: MP3, WMA, MPEG4, DivX, MKV, JPEG.
Speaker power is 24 W (2x12 W) 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 x2, audio x2, component, VGA, HDMI x4, USB x2. 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 110 W. KPS + power supply L110C3.
Dimensions: With stand 1235x787x277 mm, Without stand 1235x740x56 mm.
TV weight: 25.1 kg.
Attention! Panel LC550EUN (PE) (F1) DNS K55D709 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.