Technical description and composition of the TV SHARP LC-20T1RU, type of panel and applicable modules. The composition of the modules.SHARP
Model: LC-20T1RU
Panel: 20 inch
Inverter (backlight): DUNTKD282WE
Mainboard: KD290
Tuner: DUNTKD289
Control: LCDTV GA411WJSA
Technical Specifications LC-20T1RU
SHARP LC-20T1RU
General recommendations for repairing TV LCD
Repair of the SHARP LC-20T1RU TV is best started with a thorough external inspection and diagnosis of the malfunction. It is advisable to carefully examine the internal and external components. Any external damage can sometimes prompt the repairman to take further steps to determine the malfunction of the TV and localize the defect. 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 SHARP LC-20T1RU does not turn on, no control lights on the front panel will light or blink, therefore, there is a very high probability of a power module malfunction. It is advisable to start the troubleshooting of the power supply module by checking the mains fuse. If it is broken, it is necessary to check first of all the power semiconductor elements - rectifier diodes and the power switch of the converter, which are often found in breakdown conditions in such situations.
Power switches in flyback converters fail extremely rarely for no reason and, if they are broken, it is necessary to look for a malfunction in the stabilization circuits by checking electrolytic capacitors, semiconductor devices, and resistors in the primary circuit. The cause may be a malfunction of the PWM controller chip, which can only be checked by replacing it with a new or obviously working one.
In cases where the Power Factor Corrector (PFC) is used in the power supply, troubleshooting can be a bit more complicated.
In cases where the SHARP LC-20T1RU TV has lost an image, and the sound is there and all the other functions are functional, there is a possibility of a malfunction of the inverter (converter for powering the backlight). When you turn on the TV, the image may appear briefly and immediately disappear. It must be borne in mind that with such manifestations, the lamps themselves also fail, the malfunction of which can be detected by replacement, by connecting to the connectors for diagnostics that are known to be serviceable and suitable in power.
When repairing the DUNTKD282WE inverter, it is often necessary to disable the protection for diagnostics, which, for the purpose of fire safety, turns it off in any emergency situation, for example, during a malfunction or uneven wear of the lamps, which makes it difficult to find a defect.
It should be remembered that when the protection is turned off, there is always a risk of failure of the power elements of the inverter during diagnosis. After repair, it is necessary to restore all standard converter protection circuits.
Repair of the KD290 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.
If the TV works normally from external devices, but does not tune into television channels, the tuner DUNTKD289 may be malfunctioning. In such cases, first of all, you should make sure that there are supply voltages at its corresponding terminals, as well as the power supply of varicaps (30-33V).
Owners and users of the SHARP LC-20T1RU television 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 SHARP LC-20T1RU Chassis
Main features of the SHARP LC-20T1RU device:Installed matrix (LCD-panel) 20 inches.
To power the backlight used inverter DUNTKD282WE.
The necessary supply voltage for all nodes of the TV SHARP LC-20T1RU provides a switching power supply.
MainBoard - the main board (motherboard) is a KD290 module.
The DUNTKD289 tuner provides TV reception and channel tuning.
In some cases, before calling the repair service, you should make sure that your TV is really defective.
If the SHARP LC-20T1RU does not turn on or periodically turns off, it is useful to check the sockets and extension cords at the points where the TV is connected to the network, for example, using a regular table lamp.
If the SHARP LC-20T1RU does not respond to the remote, but the control buttons on the panel work, there is a certain probability of a malfunction of the remote (the remote does not work). It is advisable to check or replace the batteries in it.
If, when watching broadcasting programs, a notification of the absence of a signal appears (no signal), you should make sure that the TV is in the TV reception mode (digital / analog), or check the antenna or cable equipment.
You can check the operation of the TV from other external devices.
If there is no sound only when watching analog television programs, you should check the sound system in the settings. For Russia, D / K (6.5 MHz), for European countries B / G (5.5 MHz). In modern TVs, a region is usually chosen to set the color and sound standards - for Russia, “East Europe” (Eastern Europe).
If SHARP LC-20T1RU hangs during operation, does not respond to either the remote control or the buttons on the control panel, rebooting sometimes helps. To do this, you must completely disconnect the TV from the network by pulling the plug from the outlet, and turn it back on after 10-15 seconds.