LG
Model: RZ-20LZ50
Chassis / Version: ML-041B
Panel: LC201V02 (A3) (KA)
Inverter (backlight): PT-002726-2 TCI-AJS D
PWM Inverter: BTT3105P
MOSFET Inverter: FDS8958
Power Supply (PSU): TCI-AJS D / PT-002726-2 / AIV-0001 rev-M
PWM Power: NCP1203 (code 203Dx)
MOSFET Power: SSM07N70
MainBoard: 6870TA20A16 // 6870TA20A60, 6870T808J66
IC MainBoard: VCT49xyF, GM2221-LF, AT49F002AN, LA7222,
Tuner: 6700VS0003E
Control: IR: 6870T964C11
Technical Specifications RZ-20LZ50
LG RZ-20LZ50
General recommendations for repairing TV LCD
Diagnostics of malfunctions and repair of LG with the ML-041B chassis, as well as other electronic devices, is recommended to begin with an external examination of the external and internal elements. Visible damage to elements can sometimes indicate the direction of the search for a defect even before the necessary measurements are taken. 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.
Faults in the PT-002726-2 power supply module can be expressed in different ways, for example, the LG RZ-20LZ50 does not turn on at all and the control lamps on its front panel do not light up and do not blink, there are no signs of operability. It should be noted that with the same external manifestations, the processor power regulator (converter) may be faulty. In the general case, first of all, it is necessary to check the electrolytic capacitors of the secondary rectifier filters and the fuse at the input of the network. If it is broken, then you should check for breakdown of the PN junctions of the rectifier bridge diodes and the key transistor of the converter, which can either be on a separate radiator or integrated with a PWM controller in a common chip. SSM07N70 variants are possible.
It should be borne in mind that in the practice of repair it is extremely rare that key transistors in switching power supplies (SMPS) fail for no reason that should be sought by checking other components, for example, a breakdown of the key can provoke faulty elements of the damper circuits, or dried electrolytic capacitors or dangling primary resistors BP circuits involved in the stabilization process. In this case, all semiconductor elements of the strapping of the PWM controller chip are subject to verification, which it is desirable to verify by replacement.
Sometimes the LG RZ-20LZ50 TV does not have an image, but there is sound, or the image appears and immediately disappears. In this case, there is a high probability of a malfunction of the backlight converter, or of the lamps themselves, which can be checked by replacement. In such cases, it is necessary to verify the serviceability of all electrolytic capacitors of the filter according to the power supply of the inverter itself, including in the power supply unit (power supply unit). When disabling the inverter protection (to enable diagnostics), special care must be taken in view of the risk of failure of the power elements. After completing all repair work, it is imperative to restore the protection circuits for full and safe further operation of the TV by the user.
Repair or diagnostics of the ML-041B motherboard should begin by checking the stabilizers or power converters of its microcircuits. If necessary, you should update the software (software). Often, the MB (SSB) card must be replaced in case of complex malfunctions that are difficult to detect. When trying to repair, you should check its elements - VCT49xyF, GM2221-LF, AT49F002AN, LA7222, TUNER: 6700VS0003E and replace failed chips with new ones. Some malfunctions may be due to the use of BGA soldering technologies in modern Main Board technologies. Typically, such defects are detected by local heating of the chip.
Attention! For users and owners of RZ-20LZ50 TVs who do not have the appropriate qualifications, knowledge and experience, we categorically do not recommend attempting self-repair in order to avoid negative consequences that could lead to complete non-repairability of the device.
Service manual / schematic diagram -------------> LG RZ-20LZ50, RT-20LZ50 Chassis ML-041B
Main features of the device LG RZ-20LZ50:Installed matrix (LCD panel) LC201V02 (A3) (KA).
To power the backlight, an inverter PT-002726-2 is used, it is controlled by the BTT3105P PWM controller. As power elements of the inverter, keys of the FDS8958 type are used.
The necessary supply voltages for all nodes of the TV LG RZ-20LZ50 are generated by the TCI-AJS power module or its analogs using NCP1203 microcircuits (code 203Dx) and power switches of the SSM07N70 type.
MainBoard - the main board (motherboard) is a module 6870TA20A16, using microcircuits VCT49xyF, GM2221-LF, AT49F002AN, LA7222, and others.
The tuner 6700VS0003E provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: LG.Philips LCD
Model: LC201V02-A3KA
Type: a-Si TFT-LCD, Panel
Diagonal size: 20.1 inch
Resolution: 640x480, VGA
Active Area: 408x306 mm
