Technical description and composition of the LG 32LB551U TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 32LB551U
Chassis / Version: LD43B / LD44B
Panel: LC320DXE (FG) (A5) // NC320DXN
T-CON: 6870C-0442B
LED driver (backlight): integrated into PSU
PWM LED driver: SSC1S311, A27RAE (sot23-6)
MOSFET LED driver: STD11N65M5, STN4NF20L
Power Supply (PSU): LGP32-14PL1 EAX65391401 (2.6)
PWM Power: NCP1251 (PWM SOT23-6), NR134S
MOSFET Power: KP8N65
MainBoard: EAX65388003 (1.0)
IC MainBoard: CPU: LGE2132, NAND Flash: H27U1G8F2CTR, SPI Flash: 25Q80, EEPROM: 24C256, SOUND: TAS5733
Tuner: TDJM-G101D
Specifications 32LB551U
LG 32LB551U
General repair guidelines for TV LCD LED
Possible manifestations of defects
- LG 32LB551U 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 some of these cases, the main switching power supply, the LGP32-14PL1 module, is faulty. In the absence of the necessary supply voltages in the secondary circuits of the converters, it is necessary to check the power switches (KP8N65) and rectifier diodes for a possible partial or complete breakdown.
In the event of breakdowns in the secondary circuits of the converter, it can usually fail in short circuit mode, and in the event of a short circuit in the power elements of the primary circuit, the mains fuse or current sensor at the source of the key most often breaks.
Breakdown of power switches (MosFet) in pulsed sources is sometimes caused by malfunctions of other circuit elements, for example, in circuits supplying a PWM controller, frequency-setting or damper ones, as well as in negative feedback circuits (OOS) of stabilization. PWM controllers (PWM) NCP1251 (PWM SOT23-6), NR134S, if they do not have visible damage to the case and open fault between the terminals, are usually checked by replacement.
- 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.
In such cases, the most likely malfunction of the LED backlight elements. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
It is impossible to check the line of series-connected LEDs without a special current source, and for this purpose it is not safe to use any voltage sources above 12V for them. Then it remains only to open the panel and check each LED separately. Usually, Chinese 9V-powered multimeters light up a single 3-volt LED, if you connect the probes in the forward direction, the red probe to the anode, and the black to the cathode. In dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of health. In the event of a LED malfunction, its zener diode will either be cut off or broken into short-circuit.
- The TV does not turn on, the indicator indicates standby or operating mode, or blinks.
Repair or diagnostics of the EAX65388003 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: LGE2132, NAND Flash: H27U1G8F2CTR, SPI Flash: 25Q80, EEPROM: 24C256, SOUND: TAS5733 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 there is no reception of television channels, but the TV is working properly from external devices, first of all it is necessary to check the power supply to the TDJM-G101D tuner and update the software. The pulses from the I2C bus must be controlled with an oscilloscope.
Attention to users! Self-repair of the LG 32LB551U TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
Service manual and schematic diagram ------------------> LG 32LB551U Chassis LD43B / LD44B
FIRMWARE FOR SPI FLASH ------> LG 32LB551U LD43B / LD44B, Main: EAX65388003 (1.0), Panel: LC320DXE (FG)(A5)
You can reduce the backlight current in LG TVs with LGP32-14PL1 power supplies (EAX65391401) as follows. The current sensor consists of six resistors R816-R821 connected in parallel - 1 Ohm, 1 Ohm, 1 Ohm, 1 Ohm, 2 Ohm, 8.2 Ohm. The total resistance in this case will be 0.22 Ohm. If you remove one resistor 1 Ohm, the total resistance increases to 0.28 Ohm, the current decreases proportionally from 250 mA to about 190 mA.
More details on this page
The appearance of the MainBoard EAX65388003 is shown in the figure below:EAX65388003
EAX65388003 can be used in TVs:
LG 42LB551V (Panel LC420DUE (FG)(A5)), LG 42LB620V ZD (Panel LC420DUE (FG)(P2)), LG 39LB561V (Panel NC390DUN VXBP1), LG 32LF580V (Panel NC320DUN).
The appearance of the power supply
Main features of the device LG 32LB551U:
Installed matrix (LED-panel) LC320DXE (FG) (A5) or NC320DXN.
The matrix control uses the Timing Controller (T-CON) 6870C-0442B.
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by a PWM controller SSC1S311, A27RAE (sot23-6). As power elements of the LED driver, keys of the type STD11N65M5, STN4NF20L are used.
The necessary supply voltages for all nodes of the LG 32LB551U TV are generated by the LGP32-14PL1 power module or its analogs using NCP1251 (PWM SOT23-6), NR134S microcircuits and KP8N65 type power switches.
MainBoard - the main board (motherboard) is an EAX65388003 module using CPU chips: LGE2132, NAND Flash: H27U1G8F2CTR, SPI Flash: 25Q80, EEPROM: 24C256, SOUND: TAS5733 and others.
The TDJM-G101D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC320DXE-FGA5
Type: a-Si TFT-LCD, Panel
Diagonal size: 31.5 inch
Resolution: 1366x768, WXGA
Display Mode: IPS, Normally Black, Transmissive
Active Area: 697.685x392.256 mm
Surface: Antiglare (Haze 1%), Hard coating (3H)
Brightness: 300 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (6-bit + Hi-FRC), CIE1931 68%
Response Time: 7 (G to G)
Frequency: 60Hz
Lamp Type: WLED Without Driver
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 12.0V