Saturday 7 March 2020

REPAIR / SERVICING TV SONY KDL-37U4000

Technical description and composition of the TV SONY KDL-37U4000, type of panel and applicable modules. The composition of the modules.
SONY
Model: KDL-37U4000
Chassis / Version: SE2AG
Panel: T370XW02 VC
T-CON: T370XW02 VC Ctrl BD 37T03-C00
Inverter (backlight): VIT71060.50 LOGAN REV: 1
PWM Inverter: OZ964GN
Power Supply (PSU): 1-876-636-11 GA3
PWM Power: FA5501AN (PFC), MCZ3001DB, MIP2H2
MOSFET Power: 2SK3797, 2SK3568
MainBoard: 1-876-638-11 - BC1
IC MainBoard: VCT7593 A1 H08, TDA9973AHL / 8/12, CXA1444R, CXD1978, NJM3414, SIL9021CTU, D61123F1-100, HY27US0828IA
Tuner: BTF-HF412T
Technical Specifications KDL-37U4000
SONY KDL-37U4000
General recommendations for repairing TV LCD
It is advisable to start the repair and diagnostics of the SONY KDL-37U4000 TV with a careful external examination of the internal and external elements, including case parts, a display, buttons and cables. It often happens that some damage to elements or connections will help determine the correct direction of troubleshooting and localization of the defect. Experienced repairmen are often aware of the causes of the defect and the possible consequences, for example, from ring cracks in the soldering of the leads of the elements, as well as from swollen capacitors or resistors burnt to coal dust and other external indirect signs.
In the case when the KDL-37U4000 does not turn on, does not respond to the remote control and buttons on the front panel, does not blink bulbs and does not show any signs of operability, most likely in this case the GA3 power module is faulty. When repairing the power supply, it is advisable to start the diagnostics by checking the mains fuse and, in the event of an open circuit, the reason should be sought in the power semiconductor elements of the pulsed flyback converter of the main PSU. First of all, it is necessary to check the diodes of the bridge of the rectifier of the mains voltage and the power switch of the 2SK3797, 2SK3568 converter, which can be installed separately on the radiator, or integrated with a PWM controller.
It should be borne in mind that in the practice of repair it is extremely rare that key transistors of the N-FET type fail for no reason that should be sought by checking other components, for example, a breakdown of the key can provoke faulty elements of the damper circuits, either dried electrolytic capacitors or dangling resistors of the primary circuit of the PSU, involved in the stabilization process. In this case, all semiconductor elements of the strapping of the PWM regulator chip FA5501AN-D1-TE1, MCZ3001DB, MM1431AURE, MM1431AURE, MIP2H2, which it is desirable to check by replacement, are subject to verification.
When using a power factor correction unit (PFC) in the power modules, troubleshooting becomes somewhat more complicated and requires additional experience and knowledge of their operation.
If the SONY KDL-37U4000 TV does not have an image, but there is sound, the malfunction should be sought in the power converter of the backlight (inverter). It is also necessary to check the serviceability of the electrolytic capacitors of the filter of the secondary rectifiers of the BP (power supply) for an overstated ESR.
The operation of the power circuits of the inverter and the backlight in the normal mode are controlled by special protection, which is organized for fire safety, for example, to disconnect during short circuits or breaks in high-voltage connections or when the lamps are depressurized. This protection makes it difficult to diagnose and repair the inverter.
It should be remembered that when the protection is turned off, there is always a risk of failure of the inverter power elements during diagnosis. After repair, it is necessary to restore all standard converter protection circuits.
Diagnosis and repair of the BC1 motherboard is carried out by checking the performance of power stabilizers or updating the software (software). Board repair and replacement of CXD1978, NJM3414, SIL9021CTU microcircuits are carried out with the necessary equipment, and the corresponding element base.
Once again, remind users! Attempts to self-repair a SONY KDL-37U4000 TV without the appropriate qualifications and experience can lead to its complete non-repairability!


Service manual / schematic diagram ------------->   Sony KDL-26U4000 OIRT, KDL-32U4000, KDL-37U4000 CHASSIS SE2AG

PSU / schematic diagram ------------->   Sony 1-876-636-11, 1-876-636-12 GA3


 The appearance of MainBoard 1-876-638-11 is shown in the figure below:
1-876-638-11
1-876-638-11 can be used in televisions:
SONY KDL-26U4000 (Panel LTA260AP01), SONY KDL-32V4000 (Panel LTZ320AA01), SONY KDL-37S4000 (Panel T370XW02 V.C), SONY KDL-37U4000 (Panel T370XW02 VC), SONY KDL-37V4000 (Panel T370XW02 V.C).
PSU Advanced
The GA3 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 node is a Step-Up Converter based on the FA5501AN PWM controller, which 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-37U4000:
Installed matrix (LCD panel) T370XW02 VC.
The matrix control uses the Timing Controller (T-CON) T370XW02.
The VIT71060.50 inverter is used to power the backlight lamps, it is controlled by the OZ964GN PWM controller.
The necessary supply voltages for all nodes of the SONY KDL-37U4000 TV are generated by the power module 1-876-636-11, or its analogs using the FA5501AN (PFC), MCZ3001DB, MIP2H2 microchips and power switches of the type 2SK3797, 2SK3568.
MainBoard - the main board (motherboard) is a module 1-876-638-11, using VCT7593 A1 H08, TDA9973AHL / 8/12, CXA1444R, CXD1978, NJM3414, SIL9021CTU, D61123F1-100, HY27US0828IA, and others.
The BTF-HF412T tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: AUO
Model: T370XW02 VC02
Type: a-Si TFT-LCD, Panel
Diagonal size: 37 inch
Resolution: 1366x768, WXGA
Display Mode: AMVA, Normally Black, Transmissive
Active Area: 819.6x460.8 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