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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Monday, 6 April 2020

REPAIR / SERVICING TV AKAI LTA-27A901

Technical description and composition of the TV AKAI LTA-27A901, type of panel and applicable modules. The composition of the modules.
AKAI
Model: LTA-27A901
Panel: V270W1-L03
Inverter (backlight): 270W1-24-VD4
PWM Inverter: OZ960C, FDS8958A
Power Supply (PSU): 27POWER200.PCB
PWM Power: MC33260D (PFC), NCP1377DR2 (PWM flyback 8pin), NCP1203P60 (8)
MOSFET Power: FQP7N80, FQP18N50, STW12NK80Z
MainBoard: LCDTV-2601 MAINBOARD
IC MainBoard: PW113-20Q, PW1235, VPC3230D, SAA5264PS, M29LV800DT AUDIO- MSP3450, TDA8947J
Tuner: JS-6B3 / 121F2
Technical Specifications LTA-27A901
AKAI LTA-27A901
General recommendations for repairing TV LCD
Possible manifestations of defects
- The AKAI LTA-27A901 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 27POWER200.PCB 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 (FQP7N80, FQP18N50, STW12NK80Z) of 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 a short circuit in the elements of the primary circuit, the mains fuse usually breaks.
The breakdown of Mos-Fet keys used in pulsed sources is often caused by malfunctions of other elements, for example, power supply, frequency-setting, damper ... as well as elements of the Negative Stabilization Feedback. PWM chip MC33260D (PFC), NCP1377DR2 (PWM flyback 8pin), NCP1203P60 (8) can also cause a malfunction of the power switch of the converter and is checked by replacement.
- 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 the inverter.After checking all the electrolytic capacitors of the filters that are involved in the power supply of the inverter, you must ring in its converter power keys for breakdown and secondary windings of transformers for an open.
If in diagnosing a malfunction, it is necessary to disable the inverter protection, there is a risk of failure of the power elements of the inverter, and special care is required during work, and after their completion, it is necessary to restore the protection circuits for further safe operation of the TV by the owner in normal mode.
- 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 LCDTV-2601 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). Board repair and replacement of PW113-20Q, PW1235, VPC3230D, SAA5264PS, M29LV800DT AUDIO-MSP3450, TDA8947J microchips are carried out with the necessary equipment, and the corresponding element base. Faults associated with the application of BGA processor soldering technologies can be localized by the heating method.
Before changing the tuner JS-6B3 / 121F2, if it is not possible to tune to television channels, make sure that there are supply voltages that need to be measured on the corresponding terminals of the tuner and check the software for correctness. The pulses of the data exchange of the tuner with the processor can be controlled by an oscilloscope
Owners and users of the AKAI LTA-27A901 TV should remember that self-repair without special knowledge, skills and qualifications can be fraught with negative consequences that can lead to complete non-repairability of the device!
SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    AKAI 27A901


 According to the conditions of compliance with modern world standards for household switching power supplies, the 27POWER200.PCB module provides for the use of a Power Factor Correction unit. The PFC circuit is a flyback converter based on the MC33260D PWM controller. 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.
Key Features of the AKAI LTA-27A901:
Installed matrix (LCD panel) V270W1-L03.
The 270W1-24-VD4 inverter is used to power the backlight, controlled by the OZ960C, FDS8958A PWM controller.
The necessary supply voltages for all nodes of the TV AKAI LTA-27A901 are generated by the power module 27POWER200.PCB, or its analogs using microcircuits MC33260D (PFC), NCP1377DR2 (PWM flyback 8pin), NCP1203P60 (8) and power switches of the type FQP7N80, FQP18N80ZW, ST .
MainBoard - the main board (motherboard) is an LCDTV-2601 module, using chips PW113-20Q, PW1235, VPC3230D, SAA5264PS, M29LV800DT AUDIO-MSP3450, TDA8947J and others.
The JS-6B3 / 121F2 tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: CMO
Model: V270W1-L03
Type: a-Si TFT-LCD, Panel
Diagonal size: 27.0 inch
Resolution: 1280x720, WXGA
Display Mode: Super MVA, Normally Black, Transmissive
Active Area: 597.12x335.88 mm
Surface: Antiglare (Haze 40%), Hard coating (2H), Reflection 2.0% (Max.)
Brightness: 500 cd / m²
Contrast Ratio: 900: 1
Display Colors: 16.7M (8-bit), CIE1931 75%
Response Time: 15/10 (Tr / Td); 16.6 (G to G)
Frequency: 60Hz
Lamp Type: 14 pcs CCFL Embedded (Inverter)
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 5.0V
Posted By: FRANK at 06:50
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