Technical description and composition of the LG 52LG70YD TV, panel type and applicable modules. The composition of the modules.LG
Model: 52LG70YD
Chassis / Version: LB81D
Panel: EBT51597301
Power Supply (PSU): LGP52-08H Part No: B12520127012, Rev 1.3 080228, B9DPE417527011993
PWM Power: UCC28060 (PFC 16pin), STL6599D (PWM Resonant), NCP1207A (Standby)
MainBoard: 52LG70YD-AA Part No: EBU51597501
IC MainBoard: Micronas FRC9459M, CPU: LGE7363C-LF. AZ1085, AZ1117, SC1566IM, SC1565IM
Specifications 52LG5030
LG 52LG70YD
General recommendations for repairing TV LCD
Repair of electronic equipment usually begins with its external inspection and diagnosis of the malfunction. In this case, you should examine all the internal elements of the chassis, as well as the external case. According to some external signs of a change in the state of some elements, it is sometimes possible to make assumptions about the nature of the defect, as well as determine the further direction of the troubleshooting. If ring cracks are detected in the soldering of the terminals of the elements or dangling connecting tracks, swollen capacitors or charred resistors - all this can be characteristic signs of the causes or consequences of an already known typical malfunction.
In the absence of any signs of operability, when the LG 52LG70YD does not turn on and does not signal anything with the control lights on the panel, there is a possibility of a malfunction of the power module LGP52-08H, Part No: B12520127012, Rev 1.3 080228, B9DPE417527011993 of the TV. With the same manifestations, the power regulator of the control processor on the motherboard may be faulty. It is advisable to start the troubleshooting of the power supply module by checking the state of the electrolytic capacitors of the rectifier filters and the mains fuse. Defective capacitors should be replaced. If the mains fuse is broken, it is necessary to check first of all the power semiconductor elements - rectifier diodes and transistors, which are often found in such a state of breakdown.
In most cases, key breakdowns in switching power supplies (SMPS) do not occur for no reason and you should look for other faulty circuit elements that could provoke a defect. This can be dried electrolytic capacitors in the primary circuit, and faulty damper elements, as well as dangling resistors or punched semiconductor elements in the stabilization circuits. Possible defective PWM PFC chip: UCC28060, Worker: STL6599D, Standby: NCP1207A from the manufacturer.
If the LG 52LG70YD does not have an image, but there is sound, there is a possibility of a malfunction of the backlight or power converter. You should also make sure that the electrolytic capacitors of the secondary rectifiers of the common power supply are working. When disabling protection in order to enable the diagnosis of a malfunction, special care should be taken, and after completion of all repair work, it is necessary to restore the circuit and the inverter protection for further safe operation of the TV.
Diagnostics and repair of the motherboard 52LG70YD-AA.AAUQLH BRAND LB81D, Part No: EBU51597501 is carried out by checking the operability of the stabilizers or power converters of the module chips. In some cases, a software update is required. Complex repair of MB (SSB) is possible only in the conditions of a service center with the necessary equipment. Checking or replacing elements of Micronas FRC9459M, CPU: LGE7363C-LF. AZ1085, AZ1117, SC1566IM, SC1565IM requires the necessary training and professional skills to repair modules at the component level. Problems associated with the use of BGA soldering technologies can be diagnosed by warming up.
Owners and users of the LG 52LG70YD 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!
Service manual / schematic diagram ------------> LG 52LG70YD CHASSIS LB81D
The appearance of the MainBoard 52LG70YD-AA is shown in the figure below:52LG70YD-AA
PSU Advanced
According to the conditions of compliance with modern world standards for household switching power supplies, the LGP52-08H module provides for the use of a Power Factor Correction unit. The PFC circuit is a flyback converter based on the UCC28060 16pin PWM controller. The reactance of an electrolytic capacitor of a line filter at a frequency of 50-60 Hz is usually not more than 20-30 ohms and its charge directly from the network through open diodes could reach tens of amperes per pulse if no filtering were applied.
As a result of the PFC conversion, an increased voltage on the capacitor (about 380V) cannot directly open the rectifier diodes, on the anode of which the voltage will always be slightly less (about 300V) and then its charging current will always be limited by the elements of the PWM controller. As a result, the envelope of the high-frequency pulses of the consumed current will repeat the shape and phase of the input sinusoidal voltage. The presence of an increased voltage (+ 380V) on the network capacitor indicates the serviceability of the PFC node.
The appearance of the power supply
Main features of the device LG 52LG70YD:
Installed matrix (LCD panel) EBT51597301.
The necessary supply voltages for all nodes of the LG 52LG70YD TV are generated by the LGP52-08H power supply module or its analogs using UCC28060 (PFC 16pin), STL6599D (PWM Resonant), NCP1207A (Standby) microcircuits.
MainBoard - the main board (motherboard) is a 52LG70YD-AA module using Micronas FRC9459M chips, CPU: LGE7363C-LF. AZ1085, AZ1117, SC1566IM, SC1565IM and others.
