Monday 23 March 2020

REPAIR / SERVICING TV BBK 42LEM-1009

Technical description and composition of the BBK 42LEM-1009 TV, type of panel and applicable modules. The composition of the modules.
BBK LED
Model: 42LEM-1009 / FT2C
Chassis / Version: CV512H-B42
Panel: T420HVN06.1 CX420DLEDM
LED backlight: RF-AD420E32-1201S-03 A2 180.DT0-421900-0H
T-CON: T420HVN06.1 42T34-C01 + 42T34-S02 42T34-S03
LED driver (backlight): integrated into MainBoard
PWM LED driver: BIT3267
MOSFET LED driver: ME15N10
Power Supply (PSU): integrated into MainBoard
PWM Power: PWM SOT23-6
MOSFET Power: SMK0760F
MainBoard: CV512H-B42
IC MainBoard: CPU: 9206B 1533-DBN, SPI Flash: 25Q64
Tuner: DMI21-C512RH
Technical Specifications 49LEX-5048 / FT2C
BBK 42LEM-1009
General repair guidelines for TV LCD LED
Possible manifestations of defects
- BBK 42LEM-1009 does not turn on, the indicators on the front panel do not light or flash. The TV does not respond to the control buttons and the remote control.
In this case, first of all, you should check the operability of the main power source - AC / DC network voltage converter, all of whose elements are located on the MainBoard CV512H-B42 board. It is necessary to measure its output voltages, and in case of their absence (full or partial), it is necessary to check the serviceability of power switches (SMK0760F) of converters and rectifier diodes for the presence of a possible short circuit.
In case of breakdowns in the secondary circuits, the converter can operate in a short circuit mode, and during a short circuit in the elements of the primary circuit, the mains fuse 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. 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) PWM SOT23-6, in the absence of external damage and short circuit between the terminals, are checked by replacing with obviously good ones.
- There is no image, there is sound, it responds to the remote control, the channels are switched. In some cases, the image appears when you turn on and immediately disappears.
Often in such cases, there is no LED backlight. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
When trying to detect a break in the LED lines, it should be taken into account that it is difficult to do this without disassembling the panel. For example, a current source is needed to open PN junctions connected in series.
- The indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the CV512H-B42 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - CPU: 9206B 1533-DBN, SPI Flash: 25Q64 and replace failed chips with new ones. Some malfunctions may be due to the use of BGA soldering technologies in modern Main Board technologies. Typically, such defects are detected by local heating of the chip.
If you suspect a malfunction of the DMI21-C512RH tuner, first of all, you need to verify the correctness of the software, as well as the presence of the necessary voltage levels and pulses of data exchange with the processor via the I2C bus at the corresponding terminals of the tuner.
Attention TV owners! Attempts at self-repair of BBK 42LEM-1009 are not recommended by the manufacturer and can lead to serious negative consequences!


SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>   MainBoard CV512H-B42-12

 The appearance of the MainBoard CV512H-B42 is shown in the figure below:
CV512H-B42
CV512H-B42 can be used in TVs:
BBK 40LEM-1010/FT2C (Panel CX390DLEDM), BBK 32LEM-1023/TS2C (Panel V320BJ6-Q01), BBK 32LEM-3035/T2C (Panel LS320TU9A00 NJ), BBK 32LEM-1036/TS2C (Panel DS32D6AP0113), BBK 42LEM-1009/FT2C (Panel T420HVN06.1 CX420DLEDM), DEXP F40B7000E (Panel V400HJ6-PE1 CX400DLEDM).
Main features of the BBK 42LEM-1009 device:
Installed matrix (LED panel) T420HVN06.1 CX420DLEDM.
The matrix control uses the Timing Controller (T-CON) T420HVN06.1.
To power the backlight LEDs, a converter is used, combined with the main board CV512H-B42, controlled by the BIT3267 PWM controller. As the power elements of the LED driver, keys of the type ME15N10 are used.
The power module is combined with the MainBoard and is designed according to a flyback AC / DC voltage converter using PWM SOT23-6 microcircuits and power switches of the SMK0760F type.
MainBoard - the main board (motherboard) is a CV512H-B42 module, using CPU chips: 9206B 1533-DBN, SPI Flash: 25Q64 and others.
The DMI21-C512RH tuner provides TV reception and channel tuning.