REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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Saturday 21 March 2020

REPAIR / SERVICING TV BBK LT4217HD

Technical description and composition of the BBK LT4217HD TV, panel type and applicable modules. The composition of the modules.
BBK
Model: LT4217HD
Chassis / Version: RSAG7.820
Panel: V420H1-L11 revC1
Inverter (backlight): I420B1-16A-Master 4H.V2308.021 / D2
PWM Inverter: OZ9928SN (28)
MOSFET Inverter: AO4614 (8) P2804N05G
Trans Inverter: 4022Q 74500 3 (GP)
Power Supply (PSU): RSAG7.820.1185 ver.D TU25C74-1
PWM Power: 1207AP (8), MC33262D (PFC), NCP1395AP (16)
MainBoard: RSAG7.820.1410 / ROH ver C
IC MainBoard: TFA9810 Sound
Tuner: TDQ-6FT / W126ROH
Control: GX080612
Technical Specifications LT4217HD
BBK LT4217HD
General recommendations for repairing TV LCD
Possible manifestations of defects
- BBK LT4217HD TV does not turn on at all. There is no reaction to the remote control or to the control buttons from the front panel. Indicator lights do not light or flash.
With such manifestations, the RSAG7.820.1185 power module usually fails. It is necessary to measure the secondary output voltage, and in case of their absence, check the serviceability of the power switches of the converters and rectifier diodes for a short circuit.
In case of breakdowns in the secondary circuits, the converter can operate in a short circuit mode, and during short circuit in the elements of the primary circuit, the mains fuse usually breaks.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements that can put it out of operation in key mode or provoke an excess of the maximum current or voltage. It can be supply, damper circuits, or elements of OOS (negative feedback) stabilization. The reason for the breakdown of the power key may be PWM (PWM) 1207AP (8), MC33262D (PFC), NCP1395AP (16). It is checked only by replacement with a known good one.
- There is no image, but there is sound and reaction to commands from the remote control. Or the image appears immediately after turning on and disappears.
The defect can be caused by problems in the nodes or elements of the backlight of the display, or in the power supply of the lamps or inverter. If all the electrolytic capacitors of the filter according to the power supply of the inverter are working, make sure that the lamps are working, then you need to check the converter keys and the secondary windings of the transformers.
Sometimes, for diagnostic purposes, inverter protection must be disabled. In such cases, special care must be taken during work, and the protection circuits should be restored immediately after the repair is completed.
- The indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the motherboard RSAG7.820. you should start by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). When repairing an MB board, you need to check its components sound TFA9810. Defective items should be replaced. If chips with BGA soldering technology are used, a problem in its implementation is detected by the local heating of the chip.
The malfunction of the TDQ-6FT / W126ROH tuner is established after checking the software and all the supply voltages at its terminals. The data exchange of the tuner with the processor via the I2C bus can be controlled by an oscilloscope.
Attention TV owners! Attempts at self-repair of BBK LT4217HD are not recommended by the manufacturer and can lead to serious negative consequences!
Service Manual with Schematic Diagram 54 pages of 2008 on the LT4217HD, LT4219HD, LT4221HD, LT4221HDU.

The appearance of the MainBoard RSAG7.820.1037 is shown in the figure below:
RSAG7.820.1037
RSAG7.820.1037 can be used in TVs:
BBK LT2614S (Panel V260B1-L02), BBK LT3214S (Panel LC320W01 (SL)(A1)), BBK LT4214S (Panel LC420WX7 Sl A1), BBK LT3215S (Panel LC320WX3 (SL)(C1)), BBK LT4014S (Panel LTA400WT-L17), DAEWOO DLP-26H1C (Panel V260B1-L02).
PSU Advanced
According to the conditions of compliance with modern world standards for household switching power supplies, the RSAG7.820.1185 module provides for the use of a Power Factor Correction unit. The PFC circuit is a flyback converter based on the MC33262P PWM controller. The reactance of the electrolytic capacitor of the 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.
Main features of the BBK LT4217HD device:
Installed matrix (LCD panel) V420H1-L11 revC1.
To power the backlight, an I420B1-16A-Master inverter is used, it is controlled by the OZ9928SN PWM controller (28). A transformer 4022Q 74500 3 (GP) is installed in the inverter converter. As power elements of the inverter, keys of the type AO4614 (8) P2804N05G are used.
The necessary supply voltages for all nodes of the TV BBK LT4217HD are generated by the power module RSAG7.820.1185, or its analogs using microcircuits 1207AP (8), MC33262D (PFC), NCP1395AP (16).
MainBoard - the main board (motherboard) is an RSAG7.820.1410 module, using TFA9810 sound chips and others.
The TDQ-6FT / W126ROH tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: CMO
Model: V420H1-L11
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: Super MVA, Normally Black, Transmissive
Active Area: 930.24x523.26 mm
Surface: Antiglare
Brightness: 430 cd / m²
Contrast Ratio: 2000: 1
Display Colors: 16.7M (8-bit), CIE1931 72%
Response Time: 6.5 (G to G)
Frequency: 60Hz
Lamp Type: 16 pcs CCFL Embedded (Inverter)
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V



Posted By: FRANK at 07:58
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