Monday 30 December 2019

REPAIR / SERVICING TV SAMSUNG QE55Q7FAM

Technical description and composition of the SAMSUNG QE55Q7FAM TV, panel type and applicable modules. The composition of the modules.
SAMSUNG
Model: QE55Q7FAM QE55Q7FAMT
Panel: CY-QM055FLAV2H
Lamp backlight: QLED Edge LED
T-CON: integrated into MainBoard
Inverter (backlight): integrated into PSU
Power Supply (PSU): BN44-00899B L49E7-MDY
MainBoard: BN41-02572B BN94-12660J
IC MainBoard: DC / DC: VPM1RT, DAC: BURR BROWN 88002, AUDIO: TAS5747
Tuner: SOC1000M
Control: Remote: RMCRMM1AP1, WI-WIFI: WCM730Q BN59-01264A, IR: BN41-02577A
Technical Specifications QE55Q7FAM
SAMSUNG QE55Q7FAM
General repair guidelines for TV LCD
Possible manifestations of defects
- SAMSUNG QE55Q7FAM TV does not turn on, does not respond to the remote control and control panel buttons, indicators do not light up and do not blink.
With such manifestations, the BN44-00899B power module usually fails. It is necessary to measure the output voltages in its secondary circuits, and if they are completely absent, check the serviceability of the power switches and rectifier diodes for a possible breakdown (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.
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, but there is sound and reaction to commands from the remote control. Or the image appears immediately after turning on and disappears.
These manifestations can be triggered by a power supply module, or by inverter defects, as well as distortion of the currents in the lamps due to their uneven wear. If all the electrolytic capacitors of the filter according to the inverter power supply are serviceable, you should make sure that the lamps are working, then you need to check the converter keys and secondary windings of the transformers.
Sometimes, for diagnostic purposes, it is necessary to disable the inverter protection. In such cases, special care must be taken during work, and the protection circuits should be restored immediately after the repair is completed.
- The indicator on the front panel blinks, the TV does not turn on in the operating mode, it does not respond to the remote control.
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). If it is not possible to replace the MB (SSB) card, you need to check the health of its elements - DC / DC: VPM1RT, DAC: BURR BROWN 88002, AUDIO: TAS5747. Defective components should be replaced.
The malfunction of the SOC1000M tuner is established after checking the software and all supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
Once again, remind users! Attempts to self-repair a SAMSUNG QE55Q7FAM 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 QE55Q7FAM device:
Installed matrix (LCD panel) CY-QM055FLAV2H.
The matrix control uses the Timing Controller (T-CON) integrated.
To power the backlight, a converter is used, combined with the power supply.
The formation of the necessary supply voltages for all nodes of the SAMSUNG QE55Q7FAM 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.
The SOC1000M tuner provides TV reception and channel tuning.