Monday 9 March 2020

REPAIR / SERVICING TV SONY KDL-48W705C

Technical description and composition of the SONY KDL-48W705C TV, panel type and applicable modules. The composition of the modules.
SONY LED
Model: KDL-48W705C
Chassis / Version: RB2G
Panel: LSY480HN02-001
LED backlight: LM41-00110A LED STRIP 48L60 REV 1.0
LED driver (backlight): 1-894-073-11 (173532911)
PWM LED driver: BD9397EFV
MOSFET LED driver: MBR5U100
Power Supply (PSU): ACDP-100N01 19.5V 5.2A.
MainBoard: 1-894-792-21
IC MainBoard: CXD4748GB, CXD4743GB, TH58NVG3S0HTAI0, YDA179-S
Tuner: 1-894-336-12
Control: WIFI: J20H076 REV.0 GP
Technical Specifications KDL-48W705C
SONY KDL-48W705C
General repair guidelines for TV LCD LED
Possible malfunctions
- The SONY KDL-48W705C TV does not turn on and does not show any signs of operability at all. There is no reaction to the remote control and control buttons from the front panel.
In such cases, the fault should be sought first in the ACDP-100N01 power supply module. It is necessary to measure its output voltages, and in case of their absence, check the operability of the power switches of the converters and rectifier diodes for the probability of a short circuit.
In case of breakdowns of semiconductors in the secondary circuits of any converter, as a rule, it can operate in emergency short-circuit mode without output voltages, and during short circuit in the elements of the primary circuit, the main fuse and, less often, the current sensor at the source of the key are most often cut off.
The breakdown of Mos-Fet keys used in pulsed sources is often caused by malfunctions of other elements, for example, in the power supply circuit of a PWM controller, in frequency-setting or damping circuits, as well as in Negative Stabilization Feedback. PWM microcircuits are usually checked by replacement with new ones, or obviously working.
- There is no image, but there is sound and reaction to the remote control. Or for a second, the image may appear immediately after switching on.
A malfunction is usually most likely in these cases at the backlight nodes of the display matrix. The reason can be both in the power supply of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
When diagnosing, it is necessary to take into account that it is impossible to check the open in the chain of LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally, a current source. By opening the panel, each LED can be checked separately. Typically, Chinese multimeters light up a single 3-volt LED, if you connect probes in the forward direction to it. In dual 6-volt LEDs, the PN junction of its emergency zener diode can serve as an indicator of health. In the event of a LED malfunction, its zener diode will either be cut off or broken into short-circuit.
- The TV does not enter the operating mode, does not respond to the remote control. The indicator on the front panel lights constantly or blinks.
Repair or diagnostics of the 1-894-792-21 motherboard should begin by checking the stabilizers and power converters needed to power the microcircuit and matrix. If necessary, update or replace the software (software). In some cases, to repair the MB (SSB) board, it may be necessary to replace the chips - CXD4748GB, CXD4743GB, TH58NVG3S0HTAI0, YDA179-S with new or obviously working ones. In cases where BGA technologies are used, defects are usually localized by the heating method.
Before replacing the tuner 1-894-336-12, if there is no tuning to the channels, you must first check the software and the supply voltage at its terminals. It is also necessary to make sure that the tuner and processor can exchange data via I2C
We recommend the owners of the KDL-48W705C TV for repair only to qualified specialists with the necessary work experience! Self-repair attempts without the appropriate knowledge and skills can lead to irreversible negative consequences!


Service manual / schematic diagram ------------->  SONY Chassis RB2G MODEL KDL-48W705C KDL-32W705C, KDL-40W705C, KDL-40W705C/9, KDL-48W705C, KDL-48W705C/9.

 The appearance of MainBoard 1-894-792-21 is shown in the figure below:
1-894-792-21
1-894-792-21 can be used in TVs:
SONY KDL-40W705C (Panel NS5S400VND11), SONY KDL-32W705C (Panel T320HVN05.3).
Main features of the device SONY KDL-48W705C:
The matrix (LED panel) LSY480HN02-001 is installed.
The LED driver 1-894-073-11 is used to power the backlight LEDs, it is controlled by the BD9397EFV PWM controller. As power elements of the LED driver, keys of the MBR5U100 type are used.
The formation of the necessary supply voltages for all nodes of the SONY KDL-48W705C TV is carried out by the ACDP-100N01 power module, or its analogues.
MainBoard - the main board (motherboard) is a 1-894-792-21 module, using CXD4748GB, CXD4743GB, TH58NVG3S0HTAI0, YDA179-S and others.
The tuner 1-894-336-12 provides reception of television programs and tuning to channels.