Tuesday, 24 December 2019

REPAIRING / SERVICING TV SAMSUNG LE32D551K2


Technical description and composition of the SAMSUNG LE32D551K2 TV, type of panel and applicable modules. The composition of the modules.
SAMSUNG
Model: LE32D551K2 LE32D551K2W
Chassis / Version: SQ03
Panel: LTF320HN01
T-CON: S100FAPC2LV0.2
Inverter (backlight): integrated into PSU + SST320_4UA01
PWM Inverter: BD9275F
Power Supply (PSU): BN44-00438C Rev1.1
PWM Power: SQT7011K, FAN7930B (PFC)
MainBoard: BN41-01751A BN94-06412J
IC MainBoard: K9F1G08U0D, 25Q40, K4B1G1646G-BCH9, D23330AC, WT61P805, DRV612
Tuner: BN40-00197A DTS40FVL082A
Control: Remote: BN59-00484A; IR BN96-16729F (BN41-01600C) D550-12C
Specifications LE32D551
SAMSUNG LE32D551K2
General repair guidelines for TV LCD
Repair of the SAMSUNG LE32D551K2 TV should begin with a careful external inspection and diagnosis of the malfunction. In this case, it is advisable to carefully examine both internal and external components. Often, for certain external signs, it is possible to draw some conclusions about the reasons for the failure of certain elements of the circuit even before the necessary measurements are made, which will determine the further algorithm for troubleshooting and localizing the defect. In some cases, faulty elements are visible to the naked eye, for example, charred resistors or swollen metal-ceramic capacitors, or electrolytic in rectifier filters. Ring cracks formed in the soldering of the terminals of transformers or heating elements of the circuit are also frequent sources of many malfunctions with a variety of external manifestations.
If the TV does not turn on, no indicators on its front panel are lit or blinking. Also, if the TV does not respond to the remote control and buttons, it does not make any sounds or any signs of operability when it is turned on, there is a certain chance that the BN44-00438C Rev1.1 power module is defective and needs repair. Sometimes with similar manifestations, a problem can only occur in the absence of processor power, but this happens much less often. In this case, the diagnosis and repair of the common power supply should always be started by checking the mains fuse. When it is broken, it is advisable to check for a breakdown, first of all, all power semiconductor elements of the converter and the rectifier diode bridge of the network, as well as the large electrolytic capacitor of the filter of the network rectifier and the key transistor.
It should be remembered that the N-FET keys used in flyback converters rarely fail for no reason to be looked for by checking other elements of the circuit. Often the breakdown is caused by malfunctions of electrolytic capacitors or semiconductor elements in the primary circuit, or by a break in resistors in the stabilization circuits. The PWM controller chip may also cause a breakdown of the power switch of the converter.
If the power module uses an active KKM circuit (power factor control), troubleshooting is somewhat more complicated.
If the SAMSUNG LE32D551K2 does not have an image, there is sound and the channels are switched, there is a possibility of a malfunction of the display backlight, or their power converter - inverter. Sometimes when you turn on the image appears and disappears immediately. In such cases, it is necessary to check the electrolytic capacitors of the power filter of the inverter itself, including in the secondary rectifier of the main power supply.
Diagnostics and repair of the inverter are often complicated by the organization of special protection circuits, which is necessary for fire safety and turns off the inverter in any emergency situation, for example, when the lamps are worn or depressurized. Often, to localize a defect, its blocking is required.
When diagnosing with the protection off, special precautions must be taken, because there is a risk of failure of the power elements of the inverter. After the diagnosis, it is imperative to restore the protection circuits for the inverter to operate normally.
Repair or diagnostics of the BN94-06412J motherboard must be started by checking the power stabilizers. If necessary, update the software (software).
It should be remembered! Attempts to repair the SAMSUNG LE32D551K2 TV, in the absence of the necessary qualifications and experience, are categorically not recommended and are fraught with negative consequences, up to the complete non-repairability of the device!


SCHEMATICS ---->  Samsung Chassis U56A, U56B.



The appearance of the MainBoard BN41-01751A is shown in the figure below:
BN41-01751A
BN41-01751A can be used in TVs:
SAMSUNG LE32D551K2 LE32D551K2W (Panel LTF320HN01), SAMSUNG LE46D550K1 LE46D550K1W (Panel LTF460HN01), SAMSUNG LE40D551 LE40D551K2W (Panel LTF400HM03), SAMSUNG LE46D551 LE46D551 LE.
PSU Advanced
The LE32D551K2 TV is equipped with a BN44-00438C power module using the PFC (Power Factor Correction) scheme acting as an active filter to eliminate the higher harmonic components of the current consumption. The boost converter based on the FAN7930B PWM controller does not allow the input rectifier filter's electrolytic capacitor to be connected to the network directly through open diodes when the charge current determines its reactance (about 15-30 ohms at a frequency of 50 Hz). As a result of the conversion, the charging current of the capacitor will be determined in such a way that the envelope of the high-frequency pulses of the input current will repeat the phase and shape of the sine wave of the input voltage. The health check of the PFC unit is carried out by measuring the DC voltage on the capacitor of the rectifier network. In operating mode, it should be around 380V, in standby approximately 300V.
The appearance of the power supply
Main features of the SAMSUNG LE32D551K2 device:
Installed matrix (LCD panel) LTF320HN01.
The matrix control uses the Timing Controller (T-CON) S100FAPC2LV0.2.
To power the backlight, a converter is used, combined with a power supply, controlled by a BD9275F PWM controller.
The necessary supply voltages for all nodes of the SAMSUNG LE32D551K2 TV are generated by the BN44-00438C power module or its analogs using SQT7011K, FAN7930B (PFC) microcircuits.
MainBoard - the main board (motherboard) is a BN41-01751A module, using K9F1G08U0D, 25Q40, K4B1G1646G-BCH9, D23330AC, WT61P805, DRV612, and others microcircuits.
The tuner BN40-00197A DTS40FVL082A provides the reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: SAMSUNG
Model: LTF320HN01-V05
Type: a-Si TFT-LCD, Panel
Diagonal size: 31.5 inch
Resolution: 1920x1080, FHD
Display Mode: SPVA, Normally Black, Transmissive
Active Area: 698.4x392.85 mm
Surface: Antiglare (Haze 5.5%), Hard coating (2H)
Brightness: 430 cd / m²
Contrast Ratio: 5000: 1
Display Colors: 16.7M (8-bit), CIE1931 72%
Response Time: 8 (G to G)
Frequency: 60Hz
Lamp Type: 12 pcs CCFL Embedded (Balance board)
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V