Monday 30 December 2019

REPAIR / SERVICING TV SAMSUNG QE49Q7FAMU

Technical description and composition of the SAMSUNG QE49Q7FAMU TV, panel type and applicable modules. The composition of the modules.
SAMSUNG LED
Model: QE49Q7FAMU QE49Q7FAM
Panel: CY-QM049FLLV2V QLED
LED backlight: QLED
T-CON: integrated into MainBoard
LED driver (backlight): integrated into PSU
Power Supply (PSU): BN44-00899B L49E7_MDY
MainBoard: BN41-02572B BN94-12660G
IC MainBoard: DC / DC: VPM1RT, DAC: BURR BROWN 88002, AUDIO: TAS5747
Tuner: SOC1000M BN95-03860A
Control: Remote: RMCRMM1AP1, IR: BN41-02577A, WIFI: WCM730Q BN59-01264A
Technical Specifications QE49Q70RAU
SAMSUNG QE49Q7FAMU
General repair guidelines for TV LCD LED
Possible malfunctions
- SAMSUNG QE49Q7FAMU TV 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.
With such manifestations, in some cases, the BN44-00899B power module is faulty. It is necessary to measure its secondary output voltages, and if they are absent, check the power switches and rectifier diodes in the converters for a short circuit.
In case of any breakdowns in the secondary circuits, the converter can operate in emergency short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse or the current sensor at the source of the key more often 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 circuits are usually checked by replacement with new ones, or known to be working.
- 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 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.
To check the LED strips, to open all the transitions of the LEDs, several tens of volts or more are needed, it is best to use a current source for such purposes. The breakage of several PN junctions connected in series cannot be detected with a multimeter or tester. In such cases, it is necessary to open the panel and check each LED. If your multimeter cannot open the LED transitions in forward bias, you can sometimes detect the presence of a PN junction of the protective zener diode by connecting the probes in the opposite direction. If the zener diode is broken or broken in short-circuit, then the LED is faulty and needs to be replaced.
- The TV does not turn on, the indicator signals standby or working mode, or blinks.
Repair or diagnostics of the BN41-02572B motherboard should begin by checking the stabilizers and power converters needed to power the microcircuit and matrix. If necessary, you should update or replace the software (software). In cases of complex repairs of MB (SSB) and with the necessary skills and equipment, sometimes it may be necessary to replace its DC / DC chips: VPM1RT and other possible faulty components. Malfunctions associated with the application of BGA soldering technologies are usually easily diagnosed by the heating method.
If you suspect a malfunction of the SOC1000M BN95-03860A tuner, first of all, you need to verify the correctness of the software, as well as the presence of the necessary power supply voltage levels and data exchange pulses with the processor via the I2C bus at the corresponding tuner pins.
Once again, remind users! Attempts to self-repair a SAMSUNG QE49Q7FAMU TV without the appropriate qualifications and necessary experience can lead to its complete non-repairability!


The appearance of the MainBoard BN41-02572B is shown in the figure below:
BN41-02572B
The appearance of the power supply
Main features of the SAMSUNG QE49Q7FAMU device:
Installed matrix (LED panel) CY-QM049FLLV2V QLED.
The matrix control uses the Timing Controller (T-CON) integrated.
To power the backlight LEDs, a converter is used, combined with a power supply.
The formation of the necessary supply voltages for all nodes of the SAMSUNG QE49Q7FAMU TV is carried out by the BN44-00899B power module, or its analogues.
MainBoard - the main board (motherboard) is a BN41-02572B module using DC / DC chips: VPM1RT, DAC: BURR BROWN 88002, AUDIO: TAS5747 and others.
Tuner SOC1000M BN95-03860A provides the reception of television programs and tuning to channels.