Saturday 28 December 2019

REPAIRING / SERVICING TV SAMSUNG LE40R81B

Technical description and composition of the SAMSUNG LE40R81B TV, panel type and applicable modules. The composition of the modules.
SAMSUNG
Model: LE40R81B LE40R81BS-KLG
Chassis / Version: BP40EO
Panel: LTA400WT-L07
T-CON: 4046HDCM4LV0.2
Inverter (backlight): SSB400WA16V REV0.1
PWM Inverter: LX1691A
MOSFET Inverter: FQPF13N50C
Power Supply (PSU): BN44-00167A SIP400B
PWM Power: ICE1PCS02 (PFC), ICE3B0365J, FSDM0565
MOSFET Power: FQA13N50CF
MainBoard: BN41-00839E BN94-01311G
IC MainBoard: 7568U-LF, M308AOSGP, EM6A9320BI-4MG, NTP-3000, MAX232EC, 24C256BN, 74HC4052D, SIL9185CTU
Tuner: HTM2-6L2 / 235S
Technical Specifications LE40R81B
SAMSUNG LE40R81B
General repair guidelines for TV LCD
Possible manifestations of defects
- SAMSUNG LE40R81B does not turn on. The control lights do not light or flash. The TV on the remote control and the control panel buttons do not respond.
Failure in such cases should begin to be sought in the power supply circuits BN44-00167A. It is necessary to measure its output voltages and, if they are completely absent, check the power switches (FQA13N50CF) and rectifier diodes for the probability of short circuit in the converters. The operability of the standby mode node implemented on the PWM controller ICE3B0365J should be checked first.
In case of any breakdown of semiconductors 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 a current sensor at the source of the key usually 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. It can be supply, damper circuits, or elements of OOS (negative feedback) stabilization.
PWM circuits ICE1PCS02 (PFC), ICE3B0365J, FSDM0565 are checked by replacing with obviously good ones.
- There is no image, but there is sound and reaction to the remote control. Or for a second, the image may appear immediately after switching on.
The defect can be caused by problems in the nodes or elements of the backlight of the display, or in the power supply of the lamps or the inverter.After checking all the electrolytic capacitors of the filters that are involved in the power supply of the inverter, you must ring in its converter power keys for breakdown and secondary windings of transformers for an open.
If in diagnosing a malfunction, it is necessary to disable the inverter protection, there is a risk of failure of the power elements of the inverter, and special care is required during operations, and after their completion, it is necessary to restore the protection circuits for further safe operation of the TV by the owner in normal mode.
- The TV does not enter the operating mode, does not respond to the remote control. The indicator on the front panel lights up constantly or blinks.
Repair or diagnostics of the BN41-00839E 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). Board repair and chip replacement 7568U-LF, M308AOSGP, EM6A9320BI-4MG, NTP-3000, MAX232EC, 24C256BN, 74HC4052D, SIL9185CTU are made with the necessary equipment, and the corresponding element base. Faults associated with the application of BGA processor soldering technologies can be localized by the heating method.
If the TV works normally from external devices, but does not tune to television channels, the tuner HTM2-6L2 / 235S may be malfunctioning. In such cases, first of all, you should make sure that there are supply voltages at its corresponding terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus. Sometimes the cause of the inoperability of the tuner may be a software failure.
Owners and users of the SAMSUNG LE40R81B TV should remember that self-repair without special knowledge, skills and qualifications can be fraught with negative consequences that can lead to complete non-repairability of the device!

PSU SCHEMATIC --------> Samsung BN44-00167A Power supply.




 The appearance of the MainBoard BN41-00839E is shown in the figure below:
BN41-00839E
BN41-00839E can be used in TVs:
SAMSUNG LE32R81B LE32R81W (Panel LTF320AB01), SAMSUNG LE32R81BX (Panel V315B1-L01 Rev. C3), SAMSUNG LE37R82BX LE37R82B (Panel T370XW02 V6), SAMSUNG LE40R82BX (Panel LTA400WTLT. 081, LT40BTWT-L07 081, LT40BTL07
The appearance of the power supply
Main features of the SAMSUNG LE40R81B device:
Installed matrix (LCD-panel) LTA400WT-L07.
The matrix control uses the Timing Controller (T-CON) 4046HDCM4LV0.2.
To power the backlight, an SSB400WA16V inverter is used, it is controlled by the LX1691A PWM controller. As power elements of the inverter, keys of the type FQPF13N50C are used.
The necessary supply voltages for all nodes of the SAMSUNG LE40R81B TV are generated by the BN44-00167A power module or its analogs using ICE1PCS02 (PFC), ICE3B0365J, FSDM0565 microcircuits and FQA13N50CF type power switches.
MainBoard - the main board (motherboard) is a BN41-00839E module, using chips 7568U-LF, M308AOSGP, EM6A9320BI-4MG, NTP-3000, MAX232EC, 24C256BN, 74HC4052D, SIL9185CTU and others.
The HTM2-6L2 / 235S tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: SAMSUNG
Model: LTA400WT-L07
Type: a-Si TFT-LCD, Panel
Diagonal size: 40 inch
Resolution: 1366x768, WXGA
Display Mode: S-PVA, Normally Black, Transmissive
Active Area: 885.168x497.664 mm
Display Colors: 16.7M (8-bit), CIE1931 72%
Frequency: 60Hz
Lamp Type: CCFL