Monday 17 February 2020

REPAIR / SERVICING TV LG 32LF562U

Technical description and composition of the LG 32LF562U TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 32LF562U - ZC
Chassis / Version: LD55T
Panel: NC320DXN-VSBP5
LED backlight: LG Innotek DRT 3.0 32 "_A / B type Rev0.2
LED driver (backlight): integrated into PSU; 119.7V 250mA
Power Supply (PSU): EAX66171501 (2.1)
PWM Power: SSC3S111
MOSFET Power: MDF11N65B
MainBoard: EAX66203805 (1.2)
IC MainBoard: CPU: LGE2136, SPI Flash: MX25L8035EM2I, EEPROM: 24C256
Tuner: TDJM-G301D
Specifications 32LF562U
LG 32LF562U
General repair guidelines for TV LCD LED
Possible malfunctions
- The LG 32LF562U TV does not turn on at all. The control lights do not light or flash. The TV on the remote control and the control panel buttons do not respond.
With such manifestations, in some cases, the EAX66171501 power module is faulty. It is necessary to measure its output voltages and, in case of their absence, check the serviceability of power switches (MDF11N65B) and rectifier diodes in the converters for possible breakdown.
In case of diode breakdowns in the secondary circuits, the converter can operate in emergency short-circuit mode without output voltages, and during short circuit in the power elements of the primary circuit, the mains fuse and / or current sensor at the source of the key 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) SSC3S111, in the absence of external damage and short circuit between the terminals, are checked by replacing with obviously good ones.
- There is no image, but there is sound and reaction to commands from the remote control. Or the image appears immediately after turning on and disappears.
In such cases, the most likely malfunction of the LED backlight elements. The reason can be both in the power 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 will be 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 turn on, the indicator indicates standby or operating mode, or blinks.
Repair or diagnostics of the EAX66203805 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 (SSB) board, it is necessary to check the health of its elements - CPU: LGE2136, SPI Flash: MX25L8035EM2I, EEPROM: 24C256 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).
Before replacing the TDJM-G301D tuner, if there is no tuning for the channels, you must first check the software and the supply voltage at its terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus
Owners and users of the LG 32LF562U 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  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 EAX66203805 is shown in the figure below:
EAX66203805
EAX66203805 can be used in TVs:
LG 32LF564U (Panel LC320DXE (MG)(A3)), LG 42LF550V (Panel LC420DUE (MG)(A6)), LG 32LF560U ZB (Panel NC320DXN VSBP5 ), LG 42LF560V (Panel LC420DUE (MG)(A3)), LG 32LF562V (Panel NC320DUN-VBBP3 (EAJ63171201)), LG 32LF564V (Panel NC320DUN VBBP3), LG 32LF560V (Panel NC320DUN-VBBP3), LG 49LF620V 49LF620V-ZB (Panel LC490DUE (MG)(P2)), LG 42LF551C (Panel LC420DUE-MGA6).
The appearance of the power supply
Main features of the device LG 32LF562U:
Installed matrix (LED-panel) NC320DXN-VSBP5.
To power the backlight LEDs, a converter is used, combined with a power supply.
The necessary supply voltages for all nodes of the LG 32LF562U 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 EAX66203805 module, using CPU chips: LGE2136, SPI Flash: MX25L8035EM2I, EEPROM: 24C256 and others.
The TDJM-G301D tuner provides TV reception and channel tuning.