Technical description and composition of the LG 32LF550U TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 32LF550U
Chassis / Version: LD55T
Panel: LC320DXE (MG) (A1) // NC320DXN
LED driver (backlight): integrated into PSU
Power Supply (PSU): EAX66171501 (2.1)
PWM Power: SSC3S111
MOSFET Power: MDF11N65B
MainBoard: EAX66203803 (1.0)
IC MainBoard: CPU: LGE2134, NAND Flash: TC58NVG0S3HTA00, SPI Flash: MX25L8035EM2I, EEPROM: 24C256
Tuner: TDJM-G301D
Specifications 32LF550U
LG 32LF550U
General repair guidelines for TV LCD LED
Possible malfunctions
- LG 32LF550U TV does not turn on at all. There is no reaction to the remote control and control buttons from the front panel. Indicator lights do not light or flash.
In such cases, the malfunction should be sought first in the EAX66171501 power module. Then we recommend that you measure its output voltages and, if they are absent, you should check the health of the power switches (MDF11N65B) and rectifier diodes of the converters for 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 power switches, used in switching power supplies, sometimes fail due to a malfunction of any other elements that can put it out of operation in key mode or create an excess of the maximum permissible parameters of the switch. These can be elements supplying the PWM controller, frequency-setting or damping circuits, or negative feedback elements in the stabilization circuit. PWM controllers SSC3S111, in the absence of visible damage or obvious short-circuit between the terminals, are checked by replacing with new, or obviously working.
- There is no image, there is sound, it responds to the remote control. Or the image may appear for a second when turned on and immediately disappears.
In most of these cases, a malfunction is detected in the nodes and backlight elements of the LED panel. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To check the LED strips, to open all the transitions of the LEDs, several tens of volts or more are needed, it is best to use a current source for such purposes. The breakage of several PN junctions connected in series cannot be detected with a multimeter or tester. In such cases, it is necessary to open the panel and check each LED. If your multimeter cannot open the LED transitions in forward bias, you can sometimes detect the presence of a PN junction of the protective zener diode by connecting the probes in the opposite direction. If the zener diode is broken or broken in short-circuit, then the LED is faulty and needs to be replaced.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the EAX66203803 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). In some cases, to repair the MB board (SSB), it may be necessary to replace the chips - CPU: LGE2134, NAND Flash: TC58NVG0S3HTA00, SPI Flash: MX25L8035EM2I, EEPROM: 24C256 with new or obviously working ones. In cases where BGA technologies are used, defects are usually localized by the heating method.
Before changing the tuner TDJM-G301D, if it is not possible to tune to television channels, make sure that there are power supply voltages that must be measured at the corresponding terminals of the tuner and check the software for correctness. The pulses of the data exchange of the tuner with the processor can be controlled by an oscilloscope
Owners and users of the LG 32LF550U 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!
SCHEMATIC MANUAL ----------------------------> LG CHASSIS LD55T.
You can reduce the backlight current in TVs with LGP32D-15CH1 power supplies (EAX66171501) if you increase the resistance of the current sensor - the R816 resistor from 2.4 Ohm to 3 Ohm. Then the backlight current will proportionally decrease from 250 mA to 200 mA. If you install a 3.3 Ohm resistor, the current will decrease to 180 mA
More details on this page
The appearance of the MainBoard EAX66203803 is shown in the figure below:EAX66203803
The appearance of the power supply
Main features of the device LG 32LF550U:
Installed matrix (LED-panel) LC320DXE (MG) (A1) or NC320DXN.
To power the backlight LEDs, a converter is used, combined with a power supply.
The necessary supply voltages for all nodes of the LG 32LF550U TV are generated by the EAX66171501 power module or its analogs using SSC3S111 microcircuits and power switches of the MDF11N65B type.
MainBoard - the main board (motherboard) is an EAX66203803 module using CPU chips: LGE2134, NAND Flash: TC58NVG0S3HTA00, SPI Flash: MX25L8035EM2I, EEPROM: 24C256 and others.
The TDJM-G301D tuner provides TV reception and channel tuning.