Friday, 27 December 2019

REPAIRING / SERVICING TV SAMSUNG LE40A656A1F

Technical description and composition of the SAMSUNG LE40A656A1F TV, panel type and applicable modules. The composition of the modules.
SAMSUNG
Model: LE40A656A1F
Chassis / Version: N46A
Panel: LTF400HC01 A02
T-CON: FRCM_TCON_V01
Inverter (backlight): integrated into PSU
PWM Inverter: LX1692, 74UHC123A
MOSFET Inverter: 2SK3568
Power Supply (PSU): BN44-00202A - IP-271135A
PWM Power: UCC28060 (PFC), FSQ0765R (PWM)
MainBoard: BN41-00974B
IC MainBoard: MT8226, MT8291E, NTP-3100, WT61P8, SDP72, D61211GM, HYB25DC256163CE-4, K4T56163QT
Tuner: BN40-00120A
Technical Specifications LE40A656A1F
SAMSUNG LE40A656A1F
General repair guidelines for TV LCD
Repair of the SAMSUNG LE40A656A1F TV should begin with a fault diagnosis, which involves a careful inspection of the external and internal elements of the device. It often happens that visible damage to elements or connections helps determine the direction of the troubleshooting. Electrolytic capacitors of filters with a swollen body, as well as ring cracks or a layer of coal on burned-out resistors formed in soldered leads of heated elements, sometimes tell the repairman the causes of the malfunction and possible consequences.
A malfunction of the power supply is often manifested corny - the TV does not turn on, does not make any sounds, does not light up and does not blink with any indicators. First of all, it is necessary to replace the swollen capacitors of the rectifier filters, if any. If the mains fuse is broken in the power supply, in most cases a breakdown of the power key (s) is detected, which can be integrated with the PWM controller, or a separate field-effect transistor can be used. The rectifier bridge diodes and the electrolytic capacitor of the mains rectifier filter should also be checked.
Mos-Fet keys used in switching power supplies (SMPS) rarely fail for no reason to look for when checking other circuit elements. Often the breakdown is caused by malfunctions of electrolytic capacitors or semiconductor elements in the primary circuit, or by a break in the resistors in the stabilization circuits. The chip of the PWM controller UCC28060 (PFC), FSQ0765R (PWM) can also cause a breakdown of the power switch of the converter.
If the SAMSUNG LE40A656A1F TV does not have an image, but there is sound, make sure that the backlight power converter (inverter) is working properly. It is also necessary to check the electrolytic capacitors of the filter of the BP secondary rectifiers (power supply) for an overstated ESR. When disabling the inverter protection (to enable diagnostics), special care must be taken in view of the risk of failure of the power elements. After completing all repair work, it is imperative to restore the protection circuits for full and safe further operation of the TV by the user.
Repair of the BN41-00974B motherboard must begin with the diagnosis and verification of all linear stabilizers and power converters of its microcircuits. Sometimes it may be necessary to update the software (software) - flashing FLASH or EEPROM. Complex repair of MB (SSB) is possible only in the conditions of a service center with the necessary equipment. Verification or replacement of elements MT8226, MT8291E, NTP-3100, WT61P8, SDP72, D61211GM, HYB25DC256163CE-4, K4T56163QT requires the necessary training and professional skills in repairing modules at the component level. Problems associated with the use of BGA soldering technologies can sometimes be diagnosed by warming up.
If there is no reception of television channels, but the TV is working properly from external devices, first of all you need to check the voltage of the tuner BN40-00120A and update the software. The pulses from the I2C bus must be controlled with an oscilloscope.
It is necessary to remember to users that attempts to self-repair a SAMSUNG LE40A656A1F TV without the appropriate qualifications and necessary experience can lead to serious negative consequences!


SCHEMATICS ------->  Samsung Chassis: N46A, Model: LE32A65*A, LE37A65*A, LE40A65*A, LE46A65*A, LE52A65*A.


PSU SCHEMATICS ----->  BN44-00202A.




The appearance of the MainBoard BN41-00974B is shown in the figure below:
BN41-00974B
BN41-00974B can be used in TVs:
SAMSUNG LE32A556P1 LE32A556P1F (Panel LTF320HA01 A04), SAMSUNG LE37A552 LE37A552P3R (Panel T370HW02 V.4), SAMSUNG LE37A656A1 LE37A656A1FXRU (Panel T370HW02 V6), SAMSUNG LE32A558P3F (Panel LTF320HA01), SAMSUNG LE40A656A1F (Panel LTF400HC01 A02), SAMSUNG LE37A615A3F LE37A615 (Panel T370HW02 V.4), SAMSUNG LE40A556P1F (Panel V400H1-L03 REV C1), SAMSUNG LE40A558P3F LE40A558 (Panel LTF400HA03), SAMSUNG LE32A656A1F (Panel LTF320HA04).
The appearance of the power supply
Main features of the SAMSUNG LE40A656A1F device:
Installed matrix (LCD-panel) LTF400HC01 A02.
The matrix control uses the Timing Controller (T-CON) FRCM_TCON_V01.
To power the backlight, a converter is used, combined with a power supply, controlled by a PWM controller LX1692, 74UHC123A. As power elements of the inverter, keys of the 2SK3568 type are used.
The necessary supply voltages for all nodes of the SAMSUNG LE40A656A1F TV are generated by the BN44-00202A power supply module or its analogs using UCC28060 (PFC), FSQ0765R (PWM) microcircuits.
MainBoard - the main board (motherboard) is a BN41-00974B module, using chips MT8226, MT8291E, NTP-3100, WT61P8, SDP72, D61211GM, HYB25DC256163CE-4, K4T56163QT and others.
The tuner BN40-00120A provides the reception of television programs and tuning to channels.