SAMSUNG LED
Model: UE40NU7170U
Chassis / Version: BN41-02635B
Panel: NN040HGLV2V
LED backlight: Edge LED
LED driver (backlight): integrated into MainBoard
Power Supply (PSU): BN44-00947A REV1.1 L40E6_NDY
PWM Power: PFC, PWM
MOSFET Power: N-FET TO-220F
MainBoard: BN41-02635B BN94-13264E
IC MainBoard: CPU, eMMC: KLM4G1FEPD, SPI 25Q40, EEPROM: 24C512, DRAM, AUDIO: TAS5749M
Tuner: BN40-00331A
Technical Specifications UE40NU7170U
SAMSUNG UE40NU7170U
General repair guidelines for TV LCD LED
Possible malfunctions
- SAMSUNG UE40NU7170U TV does not turn on at all. There is no reaction to the remote control and control buttons from the front panel. Indicator lights do not light or flash.
Failure in such cases should begin to be sought in the power supply circuits BN44-00947A. It is necessary to measure its output voltages and, in case of their absence, check the serviceability of power switches and rectifier diodes in the converters for possible breakdown.
In case of breakdowns of semiconductors in the secondary circuits of any converter, as a rule, it can operate in emergency short-circuit mode without output voltages, and during short circuit in the elements of the primary circuit, the mains fuse and, less often, the current sensor at the source of the key are most often cut off.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements that can put it out of operation in key mode or provoke an excess of the maximum current or voltage. These can be circuits supplying the PWM controller, damping or frequency-setting circuits, or elements of OOS (negative feedback) in the stabilization circuit. PWM controllers (PWM), in the absence of external damage and a short circuit between the terminals, are checked by replacing with obviously good ones.
- There is no image, there is sound, there is a reaction to the remote control. Or immediately after turning on for a second, the image may appear and immediately disappear.
A malfunction is usually most likely in these cases at the backlight nodes of the display matrix. The reason can sometimes be in the power of the LEDs, but more often in their malfunction (breakdown or break), sometimes in the violation of the contact connections of the LED strips.
It is impossible to check the LED line for breaks without disassembling the panel with a multimeter or tester. For these purposes, it is necessary to open all series-connected PN junctions and a voltage of the order of tens of volts will be required, and ideally, a current source. Having disassembled the panel, it is necessary to check each LED separately. Chinese multimeters, as a rule, light up a single 3-volt LED in the forward direction. In the case of using dual 6-volt LEDs, the PN junction of its protective zener diode can serve as an indicator of serviceability. In faulty LEDs, the zener diode will either be cut off or broken into short-circuit.
- 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 BN41-02635B motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, you should update or replace the software (software). Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU, eMMC: KLM4G1FEPD, SPI 25Q40, EEPROM: 24C512, DRAM, AUDIO: TAS5749M and replace failed chips with new ones. Some malfunctions may be due to the use of BGA soldering technologies in modern Main Board. Typically, such defects are detected by local heating of the chip.
Before replacing the tuner BN40-00331A, if there is no tuning to the channels, you must first check the software and the supply voltage at its terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus
Once again, remind users! Attempts to self-repair a SAMSUNG UE40NU7170U TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
Main features of the SAMSUNG UE40NU7170U device:
Installed matrix (LED-panel) NN040HGLV2V.
To power the backlight LEDs, a converter is used, combined with the main board BN41-02635B.
The necessary supply voltages for all nodes of the SAMSUNG UE40NU7170U TV are generated by the BN44-00947A power module or its analogs using PFC, PWM chips and power switches of the N-FET TO-220F type.
MainBoard - the main board (motherboard) is a BN41-02635B module, using CPU chips, eMMC: KLM4G1FEPD, SPI 25Q40, EEPROM: 24C512, DRAM, AUDIO: TAS5749M and others.
The tuner BN40-00331A provides the reception of television programs and tuning to channels.
