Tuesday 10 March 2020

REPAIR / SERVICING TV SONY KLV-26S550A

Technical description and composition of the SONY KLV-26S550A TV, panel type and applicable modules. The composition of the modules.
SONY
Model: KLV-26S550A
Chassis / Version: EX2T
Panel: T260XW02 V.Q
T-CON: no
Inverter (backlight): VIT1866.50 LOGAH REV: 1
PWM Inverter: OZ964GN (20)
MOSFET Inverter: P2504BDG
Power Supply (PSU): PS6203 PS6204
PWM Power: MIP2H2 (8), CXD9841P (18), FA5501A (PFC)
MOSFET Power: K4085
MainBoard: 1-878-659-11 (A1708536B)
IC MainBoard: TDA15420E / N1C00, MB90F334APMCGE1, CXB1444R-T6
Tuner: TEQE3-L02A
Control: RM-GA016
Technical Specifications KLV-26S550A
SONY KLV-26S550A
General recommendations for repairing TV LCD
Repair of a SONY KLV-26S550A TV is advisable to start with an external inspection of all its constituent elements, both internal electronic components and external. Inspection is also subject to body elements, control buttons, screen, connectors and cords. Visible damage to elements can sometimes suggest further directions for finding a defect before starting the necessary measurements. Carbonized paint on the upper layer of resistors, electrolytic capacitors of rectifier filters swollen after boiling, cracked soldering at the terminals of heating elements or transformers can often suggest the cause of the defect and possible consequences.
In cases where the SONY KLV-26S550A TV does not turn on, does not respond to the remote control and buttons, no indicators on the front panel light up or blink, and there are no sounds and no signs of operability when turning on, the GT3 PS6203 PS6204 power supply module is most likely to be faulty or, which is much less common, there is no processor power on the motherboard. In this case, the diagnosis and repair of the common power supply should always be started by checking the mains fuse. If it breaks, it is advisable to check for a breakdown, first of all, all power semiconductor elements of the converter and the rectifier diode bridge of the network, as well as the large electrolytic capacitor of the filter of the network rectifier and the key transistor K4085.
The reasons for the breakdown of the power switch of the flyback converter of the power supply module can be different, for example, a malfunction of semiconductor elements or electrolytic capacitors in the stabilization circuits of the primary circuit, as well as a failure in the operation of the MIP2H2 (8) CXD9841P (18) 5501A (8) PWM controller or breaks resistors in its harness.
When using a power factor correction unit (PFC) in the power modules, troubleshooting becomes somewhat more complicated and requires additional experience and knowledge of the device for their operation.
In cases where the SONY KLV-26S550A TV has lost its image, and the sound is there and all other functions are operational, there is a possibility of an inverter (converter for powering the backlight) malfunction. 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.
Often, attempts to repair the VIT1866.50 LOGAH REV: 1 inverter are complicated by the fact that the fault diagnosis is complicated by the operation of its protection, which is designed to turn off the inverter in emergency conditions - when the lamps are depressurized, breaks or short circuits in high-voltage connections and other emergency situations. Lock protection to localize the defect is popular among repairmen.
It should be remembered that in such cases there is a risk of failure of the power elements of the inverter and to take special care. After carrying out repairs, the protection circuit must be restored for further safe operation of the TV.
The motherboard BT22T A1708536B must be checked if there is no reaction to the remote control and function buttons, the standby indicator blinks or lights up constantly. In such cases, if the power supply circuits of the microcircuits are working, a software update may be necessary.
If you suspect a malfunction of the TEQE3-L02A tuner, first of all, you need to make sure that the voltage of the varicaps (30-33V) is present on the corresponding output of the tuner, as well as other voltage supplying it.
We recommend the owners of the KLV-26S550A TV for repair only to qualified specialists with experience! Self-repair attempts without the appropriate knowledge and skills can lead to serious negative consequences!


schematic  manual ----------------->  Sony KLV-26S550A KLV-32S530A KLV-32S550A KLV-37S550A/L/T CHASSIS EX2T ; KLV-26S550A, KLV-32S530A, KLV-32S550A, KLV-32S550A/L, KLV-32S550A/T, KLV-37S550A.


 The appearance of the MainBoard BT22T is shown in the figure below:
BT22T
BT22T can be used in TVs:
SONY KLV-22S570A (Panel T216XW01), SONY KLV-26S550A (Panel T260XW02 V.Q), SONY KLV-37S550A (Panel T370XW02 v.c).
PSU Advanced
According to the conditions of compliance with modern world standards for household switching power supplies, the GT3 module provides for the use of a Power Factor Correction unit. The PFC circuit is a 5501A PWM boost converter. The reactance of an electrolytic capacitor of a line filter at a frequency of 50-60 Hz is usually not more than 20-30 ohms and its charge directly from the network through open diodes could reach tens of amperes per pulse if no filtering were applied.
As a result of the PFC conversion, an increased voltage on the capacitor (about 380V) cannot directly open the rectifier diodes, on the anode of which the voltage will always be slightly less (about 300V) and then its charging current will always be limited by the elements of the PWM controller. As a result, the envelope of the high-frequency pulses of the consumed current will repeat the shape and phase of the input sinusoidal voltage. The presence of an increased voltage (+ 380V) on the network capacitor indicates the serviceability of the PFC node.
The appearance of the power supply
Main features of the device SONY KLV-26S550A:
Installed matrix (LCD panel) T260XW02 V.Q.
The matrix control uses the Timing Controller (T-CON) no.
The VIT1866.50 inverter is used to power the backlight lamps; it is controlled by the OZ964GN PWM controller (20). As power elements of the inverter, keys of the type P2504BDG are used.
The necessary supply voltages for all nodes of the SONY KLV-26S550A TV are generated by the PS6203 power module or its analogs using MIP2H2 (8), CXD9841P (18), FA5501A (PFC) microcircuits and K4085 type power switches.
MainBoard - the main board (motherboard) is a module 1-878-659-11, using chips TDA15420E / N1C00, MB90F334APMCGE1, CXB1444R-T6 and others.
The TEQE3-L02A tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: AUO
Model: T260XW02 VQ
Type: a-Si TFT-LCD, Panel
Diagonal size: 26.0 inch
Resolution: 1366x768, WXGA
Display Mode: VA, Normally Black, Transmissive
Active Area: 575.769x323.712 mm
Surface: Antiglare (Haze 11%), Hard coating (3H)
Brightness: 450 cd / m²
Contrast Ratio: 3000: 1
Display Colors: 16.7M (8-bit), CIE1931 72%
Response Time: 6.5 (G to G)
Frequency: 60Hz
Lamp Type: CCFL Embedded (Inverter)
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 12.0V