Tuesday 10 March 2020

REPAIR / SERVICING TV SONY KDL-55W808A

Technical description and composition of the SONY KDL-55W808A TV, panel type and applicable modules. The composition of the modules.
SONY LED
Model: KDL-55W808A
Chassis / Version: RB2-G HE-L 3D
Panel: LC550EUF FF P2
LED backlight: 6922L-0066A 401 NLAC40225R, NLAC40225L
T-CON: LC420 / 470 / 550EUF-FFP1 Ver. 1.0
LED driver (backlight): integrated into PSU
PWM LED driver: CXA3854M
MOSFET LED driver: MDF3N50
Power Supply (PSU): APS-342 / B GL2E
PWM Power: CXA3810M (PFC & PWM resonant), MIP2H2 (StandBy)
MOSFET Power: KF7N50F, TK15A50D (PFC)
MainBoard: 1-888-101-41 BA2S
IC MainBoard: CPU: CXD4739GB; NAND Flash: TC58DVG3S0ETA00
Control: RMF-ED003, RM-ED052
Technical Specifications KDL-55W808A
SONY KDL-55W808A
General repair guidelines for TV LCD LED
Repair and diagnostics of any electronic device, in particular SONY KDL-55W808A, it is advisable to start with a careful external examination of internal and external elements. Using visible changes in the state of components, it is usually possible to determine the further direction of troubleshooting and localization of the defect before the necessary measurements are taken. 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.
In the case when the KDL-55W808A does not turn on, does not respond to the remote control and front panel buttons, does not blink bulbs and does not show any signs of operability, the APS-342 / B GL2E power supply module is probably faulty in this case. If it is serviceable with such manifestations, it is necessary to check the stabilizer (converter) of the processor power supply on the motherboard. Diagnostics and repair of the general power supply unit should always begin by checking the mains fuse and the condition of the electrolytic capacitors of the secondary rectifier filters. Defective and swollen capacitors should be replaced with new ones. If the fuse breaks, it is advisable to check for a breakdown, first of all, all the power semiconductor elements of the converter and the diode bridge of the rectifier network, as well as the large electrolytic capacitor of the filter of the rectifier network.
Mos-Fet keys used in switching power supplies (SMPS) rarely fail for no reason to look for when checking other circuit elements. Often the breakdown is caused by malfunctions of electrolytic capacitors or semiconductor elements in the primary circuit, or by a break in the resistors in the stabilization circuits. The MIP2H2 PWM controller microcircuit can also cause a breakdown of the power switch of the converter.
If there is no image when you turn on the SONY KDL-55W808A, or it appears for a second and disappears, but there is sound, most likely there is a malfunction in the backlight LED circuit of the LC550EUF FF P2 panel, or in their power converter. It is necessary to check the electrolytic capacitors of the filter of the secondary rectifiers in the general power supply unit.
To check the health of the LEDs and contact connections in their power circuit, the panel must be disassembled.
To check the LED lines for breaks without disassembling the panel, for example, a current source will help. It is impossible to open series-connected PN junctions with a simple multimeter, a voltage of the order of several tens of volts is required.
Remember! Attempts to self-repair by users of the SONY KDL-55W808A TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!


Schematic manual -------------------> Sony KDL-42W802A/805A/807A, KDL-42W808A/809A, KDL-47W802A/805A/807A/808A/809A, KDL-55W802A/805A/807A/808A/809A chassis RB1G

 Service Manual 28 pages 2013 for  model ------------------>  KDL-42W802A, KDL-42W805A, KDL-42W807A, KDL-42W808A, KDL-42W809A, KDL-47W802A, KDL-47W805A, KDL-47W807A, KDL-47W808A, KDL-47W809A, KDL-55W802A, KDL-55W805A, KDL-55W807A, KDL-55W808A, KDL-55W809A




 The appearance of MainBoard 1-888-101-41 is shown in the figure below:
1-888-101-41
1-888-101-41 can be used in TVs:
SONY KDL-47W808A (Panel LC470EUF FF P2), SONY KDL-55W808A (Panel LC550EUF FF P2).
PSU Advanced
The APS-342 / B GL2E power supply module is made using the 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 CXA3810M & PWM resonant PWM controller that evenly distributes high-frequency pulses of the charging current of the electrolytic capacitor of the rectifier filter of the mains voltage 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 device SONY KDL-55W808A:
Installed matrix (LED-panel) LC550EUF FF P2.
The matrix control uses the Timing Controller (T-CON) LC420.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by a CXA3854M PWM controller. As power elements of the LED driver, keys of the MDF3N50 type are used.
The necessary supply voltages for all nodes of the SONY KDL-55W808A TV are generated by the APS-342 power module or its analogs using CXA3810M (PFC & PWM resonant), MIP2H2 (StandBy) microcircuits and power switches of the KF7N50F, TK15A50D (PFC) type.
MainBoard - the main board (motherboard) is a module 1-888-101-41, using CPU chips: CXD4739GB; NAND Flash: TC58DVG3S0ETA00 and others.
Additional technical information about the panel:
Brand: LG Display
Model: LC550EUF-FFP2
Type: a-Si TFT-LCD, Panel
Diagonal size: 55 inch
Resolution: 1920x1080, FHD
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 1209.6x680.4 mm
Surface: Antiglare, Hard coating (2H)
Brightness: 380 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M / 1.06B (8-bit / 8-bit + Dithering), CIE1931 72%
Response Time: 5 (G to G); 8 (MPRT)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: V-by-One 4 lane, 92 pins
Voltage: 12.0V