Wednesday 19 February 2020

REPAIR / SERVICING TV LG 32LM620T

Technical description and composition of the LG 32LM620T TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 32LM620T
Chassis / Version: LD22E
Panel: LC320EUN (SE) (F3)
LED backlight: 6922L-0011A 1-1
T-CON: 32.37.42.47.55 FHD TM120 VER0.2 6870C-0401B
LED driver (backlight): PPW-LE32SE-O (A) REV0.5 6917L-0080A
PWM LED driver: SW5516
MOSFET LED driver: FDD850N10L
Power Supply (PSU): EAX64310001 (1.7) REV1.0 EAY62512401
PWM Power: FAN7930B (PFC), L6599AD, ICE3BR4765JZ (ICE3B0365J Standby)
MOSFET Power: TK6P60V
MainBoard: EAX64307906 (1.0) EBR75429102
IC MainBoard: LCE2112, H5TQ2G63DFR, KLM2G1HE3F, MICOM R5F100GEA, TPS65178, STA3808WE, 24C16
Tuner: TDSN-G351D
Control: MB32B00 1BF-3010B EBR74986703
Specifications 32LM620T
LG 32LM620T
General repair guidelines for TV LCD LED
Possible manifestations of defects
- The LG 32LM620T TV does not turn on and does not show any signs of operability at all. There is no reaction to the remote control and control buttons from the front panel.
With such manifestations, the EAX64310001 power module usually fails. In the absence of the necessary supply voltage in the secondary circuits of the converters, it is necessary to check the power switches (TK6P60V) and rectifier diodes for a possible partial or complete 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 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 FAN7930B (PFC), L6599AD, ICE3BR4765JZ (ICE3B0365J Standby), in the absence of visible damage or explicit short-circuit between the terminals, are checked by replacing with new ones, or obviously working.
- There is no image, but there is sound, it reacts to the remote control. Or the image appears when you turn it on and immediately disappears
Usually in such cases, a malfunction is detected in the backlight nodes of the LED panel. 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 detect a break in the LED line without disassembling the panel with a simple multimeter. The LEDs are connected in series and to open their transitions, a voltage of several tens of volts is required. Ideally, a current source is suitable for such purposes. You can open the panel and check each LED separately. Typically, Chinese multimeters light up a single 3-volt LED, if you connect the probes in the forward direction to it (red probe to the anode, 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 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 EAX64307906 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). Sometimes it is necessary to check or replace (if necessary) the elements of the MainBoard board - LCE2112, H5TQ2G63DFR, KLM2G1HE3F, MICOM R5F100GEA, TPS65178, STA3808WE, 24C16. In cases where the BGA processor is used, its malfunction is usually detected by the local heating method.
The malfunction of the TDSN-G351D tuner is established after checking the software and all the supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
Owners and users of the LG 32LM620T 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  --------------> LG CHASSIS LD22E; 32LM620S, 32LM6620T, 32LM620S-ZE, 32LM620T-ZE.


 To reduce the backlight current in LED drivers with the SW5516 controller, it is necessary to proportionally increase the total resistance of the resistors connected between the 28 output of SW5516 and the housing, for example, by removing one of the resistors. You can calculate the resistance when connecting resistors in parallel

More details on this page


 The appearance of the MainBoard EAX64307906 is shown in the figure below:
EAX64307906
EAX64307906 can be used in TVs:
LG 32LM640T ZA (Panel LC320EUA PE F2), LG 32LS570T (Panel LC320EUN (SE)(M2)), LG 47LM620S (Panel LC470EUE (SE)(F4)), LG 42LM670T (Panel LC420EUG(PE)(F2)), LG 42LM640T 42LM640S (Panel LC420EUG (PE)(F1)), LG 42LM620T (Panel LC420EUE (SE)(F1)), LG 47LM660T (Panel LC470EUG (PE)(F1)), LG 42LS570T (Panel T420HVN01.0), LG 42LS570S ZB (Panel LC420EUE (SE)(M1)), LG 42LM669T (Panel LC420EUG (PE)(F2)), LG 42LM669S (Panel LC420EUG (PE)(F1)), LG 37LM620T (Panel LC370EUN (SE)(F2)), LG 47LM669 (Panel LC470EUG (PE)(F2)), LG 32LS570S ZB (Panel LC320EUN (SE)(M2)), LG 47LM620T (Panel LC470EUE (SE)(F3)), LG 47LM761T ZA (Panel LC470EUH (PE)(F1), LG 32LM620S (Panel LC320EUN (SE)(F2) ), LG 47LM670T 47LM670T-ZA.BRUWLJU (Panel LC470EUG (PE)(F1)), LG 42LM660S 42LM660S-ZA.BRUWLJU (Panel LC420EUG (PE)(F1)), LG 42LM660T 42LM660T-ZA.BRUWLJU (Panel LC420EUG (PE)(F1) ), LG 32LM620T (Panel LC320EUN (SE)(F3)), LG 55LM620T 55LM620T-ZE (Panel LC550EUE (SE)(F1)).
The appearance of the power supply
Main features of the device LG 32LM620T:
Installed matrix (LED-panel) LC320EUN (SE) (F3).
The matrix control uses the Timing Controller (T-CON) 3237424755.
The LED driver PPW-LE32SE-O (A) is used to power the backlight LEDs, it is controlled by the PWM controller SW5516. As the power elements of the LED driver, keys of the FDD850N10L type are used.
The necessary supply voltages for all nodes of the LG 32LM620T TV are generated by the EAX64310001 power module, or its analogs using FAN7930B (PFC), L6599AD, ICE3BR4765JZ (ICE3B0365J Standby) microcircuits and TK6P60V power switches.
MainBoard - the main board (motherboard) is an EAX64307906 module, using microcircuits LCE2112, H5TQ2G63DFR, KLM2G1HE3F, MICOM R5F100GEA, TPS65178, STA3808WE, 24C16 and others.
The TDSN-G351D tuner provides television reception and channel tuning.