Sunday 15 March 2020

REPAIR / SERVICING TV LC-32A47RU-BK

Technical description and composition of the SHARP LC-32A47RU-BK TV, panel type and applicable modules. The composition of the modules.
SHARP
Model: LC-32A47RU-BK
Panel: LK315T3GW4AY
Inverter (backlight): DUNKTF071WE, QPWBGF071WJZZ
PWM Inverter: BD9877FS, NJM2903
MOSFET Inverter: FDPF3860T
Trans Inverter: A343W
Power Supply (PSU): KF063WJ - QPWBFF063WJZZ
PWM Power: STR-Y6476, 1606B (PFC)
MOSFET Power: K3797
MainBoard: DUNTKF067 - QPWBXF067WJN1
IC MainBoard: VCT7993P A1 H000 Memory: S64 LCX157 SII9025CTU, LR388F5, BD8165, 95128WP, M2301ENE
Tuner: NQA054W
Control: GA607WJSA
Technical Specifications LC-32A47
SHARP LC-32A47RU-BK
General recommendations for repairing TV LCD
It is advisable to start diagnosing the malfunction of the SHARP LC-32A47RU-BK TV, like all others, with an external examination of possible changes, both external and internal elements. Any external damage can sometimes prompt the repairman to take further steps to determine the malfunction of the TV and localize the defect. In some cases, faulty elements can be seen with the naked eye, for example, charred resistors or swollen metal-ceramic capacitors, or electrolytic in rectifier filters. Ring cracks formed in the soldered terminals of transformers or heating elements of the circuit are also frequent sources of many malfunctions with a variety of external manifestations.
If the SHARP LC-32A47RU-BK does not turn on, no control lights on the front panel will light or blink, therefore, there is a very high probability of a malfunction of the KF063WJ power module. 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 K3797 converter, which are often found in a breakdown state in such situations.
The reasons for the breakdown of the power switch of the flyback converter of the power module can be different, for example, a malfunction of semiconductor cells or electrolytic capacitors in the stabilization circuits of the primary circuit, as well as a failure in the operation of the STRY6476 PWM controller chip or broken resistors in its bundle.
Diagnostics of power modules with a Power Factor Corrector (CMC) is somewhat more complicated and requires a more detailed approach.
In cases where the SHARP LC-32A47RU-BK TV has lost an image, and the sound is there and all other functions are operational, there is a possibility of an inverter (converter for powering the backlight) malfunctions. 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.
Diagnosis of the DUNKTF071WE inverter can be difficult due to the protection being triggered, which is organized by the designers to prevent negative consequences or fires in emergency cases, for example, during short circuits or breaks in the lamp power supply circuit, as well as their possible depressurization. To make the necessary measurements at control points or to take the necessary waveforms, repairmen have to block the protection circuits in order to be able to diagnose.
All necessary precautions must be observed when disabling the inverter protection during diagnostics and not leaving it disconnected after the repair is completed.
When repairing an MB board, you must check its components BD8165 SI19025LTU. Defective items should be replaced.
If the TV works normally from external devices, but does not tune into television channels, the tuner DUNTKF067 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).
Attention to users! Self-repair of a TV SHARP LC-32A47RU-BK without the appropriate qualifications and experience can lead to its complete non-repairability!



Service manual / schematic diagram -------------->  
SHARP LC-32A47RU-BK Chassis  LC-32A47E, LC-32A47RU, 

 The appearance of the MainBoard DUNTKF067 is shown in the figure below:
DUNTKF067
PSU Advanced
The KF063WJ power module is made using a Power Factor Correction (PFC) scheme to eliminate multiple AC harmonics introduced into the power supply by the device. The PFC assembly is a Step-Up Converter based on a 1606B PWM controller that evenly distributes high-frequency impulses of the charging current of the electrolytic capacitor of the rectifier filter of the mains voltage evenly over a period of 50 Hz. The current of its charge in this case will already be determined not by its reactance (usually 10-30 ohms for the network frequency), but by the elements of the converter. As a result, a change in the amplitude of the pulses (envelope) of the consumed current of the converter will repeat the shape and phase of the input sinusoidal voltage. The availability of an increased voltage (about + 380V) in the operating mode on the capacitor of the line filter indicates the serviceability of the PFC node.
The appearance of the power supply
Main features of the SHARP LC-32A47RU-BK device:
Installed matrix (LCD panel) LK315T3GW4AY.
To power the backlight, an inverter DUNKTF071WE is used, it is controlled by the PWM controller BD9877FS, NJM2903. A transformer A343W is installed in the inverter converter. As power elements of the inverter, keys of the FDPF3860T type are used.
The necessary supply voltages for all nodes of the SHARP LC-32A47RU-BK TV are generated by the KF063WJ power supply module or its analogs using STR-Y6476, 1606B (PFC) microcircuits and K3797 type power switches.
MainBoard - the main board (motherboard) is a DUNTKF067 module, using VCT7993P A1 H000 Memory chips: S64 LCX157 SII9025CTU, LR388F5, BD8165, 95128WP, M2301ENE and others.
The NQA054W tuner provides TV reception and channel tuning.