Wednesday 19 February 2020

REPAIR / SERVICING TV LG 32LN548C

Technical description and composition of the LG 32LN548C TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 32LN548C
Chassis / Version: LD3AC
Panel: LC320DXE (SF) (R1)
T-CON: 32/37 ROWW2.1 HD VER0.1 6870C-0442B
LED driver (backlight): integrated into PSU; 70.3V 400mA
PWM LED driver: MAP3202
MOSFET LED driver: FDT86106, AP18N20GH
Power Supply (PSU): EAX64905001 (2.7) LGP32I-13PL1 EAY62810301
PWM Power: SSC1S311A (PWM flyback), NR891D (PWM Step-down 24/12)
MOSFET Power: MDF11N65B
MainBoard: EAX65120902 (1.0)
Tuner: TDSN-G301D (B)
Control: AKB73715679
Specifications 32LN548C
LG 32LN548C
General repair guidelines for TV LCD LED
Repair of electronic equipment usually begins with its external inspection and diagnosis of the malfunction. In this case, you should examine all the internal components of the LG 32LN548C TV, as well as the external elements of the housing. A visible physical change in some components can sometimes suggest a further troubleshooting direction. Swollen electrolytic or cermet capacitors, charred resistors, ring cracks in the soldered terminals of the elements - all this can significantly help the master to determine the causes and consequences of the malfunction of the TV.
If the TV does not turn on, no control lights are on or blinking, there are no sounds when you turn on, and there is not the slightest sign of operability - the most likely malfunction is in the power module. After checking the mains fuse and power elements of the primary power supply circuit, it should also check the absence of a short circuit in the loads of the secondary rectifiers.
If a breakdown of the power switch is detected, it should be remembered that in a switching power supply (IIP) it does not fail by itself without any reasons that should be sought by checking other elements of the primary circuit - electrolytic capacitors, a PWM controller, which can only be checked replacement, as well as other semiconductor elements (diodes, transistors, zener diodes).
In cases where the LG 32LN548C TV has lost its image, and the sound is there and all other functions are operational, there is a possibility of a malfunction of the LED driver (converter for powering the backlight LEDs of the LC320DXE (SF) panel (R1)). When you turn on the TV, the image may appear briefly and disappear immediately. It must be borne in mind that with such manifestations the LEDs themselves also fail.
In case of breaks in the LED circuit, a complete disassembly of the panel is required, the LEDs are checked for an open circuit, as well as the reliability of the connections in the connectors and rations of the terminals.
When trying to detect a break in the LED lines, it should be taken into account that it is difficult to do this without disassembling the panel. For example, a current source is needed to open PN junctions connected in series.
Repair of the EAX65120902 (1.0) motherboard should begin with the diagnosis and verification of all linear stabilizers and power converters of its microcircuits. Sometimes it may be necessary to update the software (software) - flashing FLASH or EEPROM.
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 voltage of the TDSN-G301D (B) tuner and update the software.
Owners and users of the LG 32LN548C TV must 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!
One of the typical malfunctions of the LG 32LN548C often occurs in LED panels LC320DXE (SF) (R1) manufacturer LG.
External manifestations: there is no image, the backlight does not work. In most of these cases, the LEDs turn out to be faulty, which, when tested, turn out to be either open or with broken internal zener diodes.
LEDs must be replaced, and the maximum current from the driver is limited to 10-20%.


 To reduce the backlight current in TVs with the LGP32-13PL1 power supply unit (EAX64905001), you can increase the resistance of the current sensor, which consists of a set of pairs of low-impedance resistors R822-R829, only 4 pairs of 3.9 + 4.3 Ohm.
Having repaired one pair, we increase the nominal value of the sensor by 25%, which proportionally reduces the current in the LEDs from 400 mA to 300 mA.

More details on this page


SCHEMATIC ----------> LG CHASSIS: LD3AC MODEL: 32LP360H, 32LP361H, 32LN548C, 32LN549C, 32LP360H, 32LP361H-ZA 32LN548C, 32LN549C-ZA.


PSU SCHEMATIC ---------->  LG LGP32-13PL1, LGP32I-13PL1



 Main features of the device LG 32LN548C:
Installed matrix (LED-panel) LC320DXE (SF) (R1).
The matrix control uses the Timing Controller (T-CON) 32.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the MAP3202 PWM controller. As power elements of the LED driver, keys of the type FDT86106, AP18N20GH are used.
The necessary supply voltages for all nodes of the LG 32LN548C TV are generated by the EAX64905001 power module or its analogs using SSC1S311A (PWM flyback), NR891D (PWM Step-down 24/12) microcircuits and MDF11N65B type power switches.
MainBoard - the main board (motherboard) is an EAX65120902 module.
The TDSN-G301D (B) tuner allows you to receive television programs and tune to channels.
Information from an alternative source:
LG 32LN548C-ZA Chassis LD3AC
Panel Type (Matrix): LC320DXE (SF) (R1)
Motherboard: EAX65120902 (1.0), Tuner: TDSN-G301D (B)
T-con: 32/37 ROWW2.1 HD VER0.1 6870C-0442B
PSU: LGP32I-13PL1 EAX64905001 (2.7)
Remote control: AKB73715679
Additional technical information about the panel:
Brand: LG Display
Model: LC320DXE-SFR1
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: 6 (G to G)
Frequency: 60Hz
Lamp Type: WLED Without Driver
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 12.0V