Technical description and composition of the SHARP LC-20S5E-BK TV, panel type and applicable modules. The composition of the modules.SHARP
Model: LC-20S5E-BK
Chassis / Version: CMF102B PAL
Panel: LK197V3GZ91
Inverter (backlight): CEF279A
MOSFET Inverter: C5886A
Power Supply (PSU): CEF279A PSU + inverter -
PWM Power: STR-W6765, FMX22S,
MainBoard: CMF102B PAL
IC MainBoard: VCT6773G B3 000, 24C256BN, KE454U2380, BD8139AEFV, LA42052, LA5779
Tuner: TAFV-W323D
Control: GA339WJSA
Appearance
SHARP LC-20S5E-BK
General recommendations for repairing TV LCD
Like any other TV, it is advisable to start repairing the SHARP LC-20S5E-BK with an external inspection of the visible changes in the external and internal elements. In some cases, visible external damage to the elements can suggest directions for troubleshooting and localizing the defect before starting the necessary measurements at the control points of the nodes of electronic circuits. Ring cracks in the soldering of the leads of the heating elements, swollen electrolytic capacitors, a charred paint layer on the resistors - all this for the repairman can be a hint in the assumptions about the causes and consequences of the malfunction.
Malfunctions of the CEF279A PSU + inverter power supply module - can be expressed in different ways, for example, the SHARP LC-20S5E-BK 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. When diagnosing and repairing the power supply, first of all, it is necessary to check the fuse and, if it is broken, it is necessary to identify the cause. Often in such cases, an avalanche (thermal) breakdown is detected in the power semiconductor elements of the module - rectifier diodes or power switch.
It should be remembered that in the practice of repair, usually the power keys of N-Fet converters do not fail due to their poor quality and, in such cases, it is necessary to look for the cause that led to a malfunction and provoked a breakdown of the key. Most often, the culprits of the accident are dried electrolytic capacitors or dangling resistors in the primary circuit, or the PWM controller microcircuit STRW6765, FMX22S, may be faulty. It is also necessary to check all the semiconductor elements of the stabilization circuit in the primary and secondary circuits.
When using the Active Power Factor Correction (CMC) circuitry in the power module, the search for faulty elements is somewhat more complicated.
If the SHARP LC-20S5E-BK does not have an image, there is sound and the channels are switched, there is a possibility of a malfunction of the display backlight, or their power converter - inverter. Sometimes when you turn on the image appears and disappears immediately. In such cases, it is necessary to check the electrolytic capacitors of the power filter of the inverter itself, including in the secondary rectifier of the main PSU.
The operation of the power circuits of the inverter and the backlight in the normal mode are controlled by special protection, which is organized for fire safety, for example, to disconnect during short circuits or breaks in high-voltage connections or when the lamps are depressurized. This protection makes it difficult to diagnose and repair the inverter.
When diagnosing with the protection off, special precautions must be taken, because there is a risk of failure of the power elements of the inverter. After the diagnosis, it is imperative to restore the protection circuits for the inverter to operate normally.
Repair of the CMF102B PAL motherboard must begin with the diagnosis and verification of all linear stabilizers or power converters of its microcircuits. Sometimes it may be necessary to update the software (software) - flashing FLASH or EEPROM. In some cases, it is necessary to check or replace (if necessary) the elements of the MB board (SSB) - VCT6773G B3 000, 24C256BN, KE454U2380, BD8139AEFV, LA42052, LA5779.
Before replacing the TAFV-W323D tuner, if there is no tuning for the channels, first you need to check the supply voltage at its terminals, including the power supply of varicaps (30-33V).
Owners and users of the SHARP LC-20S5E-BK 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!
schematic / manual -------------------> Sharp LC-20S5E-BK
The appearance of the MainBoard CMF102B is shown in the figure below:CMF102B
CMF102B can be used in TVs:
SHARP LC-20S5E-BK (Panel LK197V3GZ91), SHARP LC-20V1RU-BK (Panel LK197V3GZ91).
Main features of the SHARP LC-20S5E-BK device:
Installed matrix (LCD panel) LK197V3GZ91.
To power the backlight used inverter CEF279A. As power elements of the inverter, keys of the type C5886A are used.
The necessary supply voltages for all nodes of the SHARP LC-20S5E-BK TV are generated by the power module CEF279A, or its analogs using microcircuits STR-W6765, FMX22S,.
MainBoard - the main board (motherboard) is a CMF102B module, using VCT6773G B3 000, 24C256BN, KE454U2380, BD8139AEFV, LA42052, LA5779 and other chips.
The TAFV-W323D tuner provides TV reception and channel tuning.
