Technical description and composition of the LG 28LN450U TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 28LN450U ZB
Chassis / Version: LD31T
Panel: 328041561 Kenmos
LED backlight: LG INNOTEK 28INCH 4014PKG 56EA
T-CON: MT3151A05-1-XC-7
LED driver (backlight): MT2751A01-1-P-4
Power Supply (PSU): Adapter 19V
MainBoard: EAX65303801 (1.2) EBR77200503
IC MainBoard: LGE2121, H5TQ2G63CFR, NTP7513
Tuner: TDSQ-G601D (B) EBL61240503
Specifications 28LN450U
LG 28LN450U
General repair guidelines for TV LCD LED
Possible malfunctions
- LG 28LN450U does not turn on, the indicators on the front panel do not light up and do not blink. The TV does not respond to the control buttons and the remote control.
Often in such cases, the Adapter power module is faulty.
This TV model is equipped with an external power adapter type Adapter 19V, which the owner can purchase independently, and repairing it may not always be advisable, however, sometimes there is a certain sense to open it and eliminate simple typical defects typical of IPS. Then we recommend that you measure its output voltages and, if they are absent, you should check the health of the power switches and rectifier diodes of the converters for possible short-circuit.
In case of any breakdowns 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 the current sensor at the source of the key more often 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, in the absence of visible damage or frank 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.
The most likely in these cases is a malfunction of the LED backlight. The reason can be both in the power supply of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
It is impossible to check the LED line for breaks without disassembling the panel with a multimeter or tester. For these purposes, it is necessary to open all series-connected PN junctions and a voltage of the order of tens of volts is required, and ideally, a current source. Having disassembled the panel, it is necessary to check each LED separately. Chinese multimeters, as a rule, light up a single 3-volt LED in the forward direction. In the case of using dual 6-volt LEDs, the PN junction of its protective zener diode can serve as a health indicator. In faulty LEDs, the zener diode will either be cut off or broken into short-circuit.
- The TV does not enter the operating mode, does not respond to the remote control. The indicator on the front panel lights constantly or blinks.
Repair or diagnostics of the EAX65303801 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 cases of attempts to repair the MB board (SSB), it is necessary to check the serviceability of its elements - LGE2121, H5TQ2G63CFR, NTP 7513 which may require replacement with new ones. If a BGA processor is installed, there is a possibility of a violation of the soldering of the contacts of its conclusions with the board (it is diagnosed by heating).
If a TDSQ-G601D (B) EBL61240503 tuner is suspected, it is first necessary to verify the correctness of the software, as well as the presence of the required power supply voltage levels and data exchange pulses with the processor via the I2C bus on the corresponding tuner pins.
Owners and users of the LG 28LN450U 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!
Service manual and schematic diagram LG 28LN450U Chassis LD31T
The appearance of the MainBoard EAX65303801 is shown in the figure below:EAX65303801
Main features of the device LG 28LN450U:
Installed matrix (LED-panel) 328041561 Kenmos.
The matrix control uses the Timing Controller (T-CON) MT3151A05-1-XC-7.
The LED driver MT2751A01-1-P-4 is used to power the backlight LEDs.
To power all the internal components of the LG 28LN450U TV, an external adapter 19V type source is used.
MainBoard - the main board (motherboard) is an EAX65303801 module, using LGE2121, H5TQ2G63CFR, NTP7513 and other chips.
Tuner TDSQ-G601D (B) EBL61240503 provides the reception of television programs and tuning to channels.