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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Friday 20 March 2020

REPAIR / SERVICING TV BBK LT1904S

Technical description and composition of the BBK LT1904S TV, type of panel and applicable modules. The composition of the modules.
BBK
Model: LT1904S
Panel: M190A1-P0A / PV190WTVM CD4H
Inverter (backlight): LIPS
PWM Inverter: TL494C
Power Supply (PSU): 49-860-AB0-190DTLTC-SH 730-102-190DTLTCH
PWM Power: LD7575PS (PWM flyback)
MOSFET Power: P10NK60ZFP. 4511GD (8n
MainBoard: 200-000-MS97885-S3H
IC MainBoard: MST97885LD, AT24C32AN, 25L4005AMC, EM638165TS-66, TDA1517P, WM8521HCGED
Tuner: JS-6H2 / 121
Technical Specifications LT1904S
BBK LT1904S
General recommendations for repairing TV LCD
Possible malfunctions
- BBK LT1904S does not turn on at all and does not show any signs of operability. Does not blink indicators and does not respond to control buttons.
Often in such cases, the 49-860-AB0-190DTLTC-SH power module is faulty. It is necessary to measure the output voltages in the secondary circuits, and if they are absent, check the operability of the power switches (P10NK60ZFP. 4511GD (8h) 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 power 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, frequency-setting, damper ... as well as elements of the Negative Stabilization Feedback. PWM chip LD7575PS (PWM flyback) can also cause a malfunction of the power switch of the converter and is checked by replacement.
- There is no image, there is sound, it responds to the remote control, the channels are switched. In some cases, the image appears when you turn on and immediately 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 when working, and after they are finished, 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 200-000-MS97885-S3H 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). In cases of attempts to repair the MB (SSB) board, it is necessary to check the health of its elements - MST97885LD, AT24C32AN, 25L4005AMC, EM638165TS-66, TDA1517P, WM8521HCGED which may require replacement with new ones. If a BGA processor is installed, there is a possibility of a violation of the soldering of the contacts of its conclusions with the board (it is diagnosed by heating).
The malfunction of the tuner JS-6H2 / 121 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 to users! Self-repair of the BBK LT1904S TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!

 SCHEMATIC / MANUAL ------------->   LT1504S, LT1904S, LT2004S 

SCHEMATIC / MANUAL ------------->   BBK LT1504S, LT1904S, LT2004S (DK1594-TP0)

Service Manual with Schematic Diagram 39 pages 2006 on model LT1904S
 
 

 The appearance of the MainBoard CV7050LA is shown in the figure below:
CV7050LA
CV7050LA can be used in TVs:
BBK LT1902S (Panel M190A1-P0A), BBK LT2202S (Panel M216H1-P01), BBK LT2428HD (Panel V236H1-P01 HK236WLCM-CH03H), BBK LT2428S (Panel V236H1-P01), FUSION FLTV-19W6 (Panel M190A1-P0A), IZUMI TL26H615B (Panel M260TWR1).
Main features of the BBK LT1904S device:
Installed matrix (LCD panel) M190A1-P0A / PV190WTVM CD4H.
To power the backlight, a LIPS inverter is used, it is controlled by the TL494C PWM controller.
The necessary supply voltages for all nodes of the TV BBK LT1904S are generated by the 49-860-AB0-190DTLTC-SH power supply module or its analogs using LD7575PS microchips (PWM flyback) and power switches of the P10NK60ZFP type. 4511GD (8n.
MainBoard - the main board (motherboard) is a 200-000-MS97885-S3H module, using microcircuits MST97885LD, AT24C32AN, 25L4005AMC, EM638165TS-66, TDA1517P, WM8521HCGED and others.
The JS-6H2 / 121 tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: CHIMEI INNOLUX
Model: M190A1-P0A
Type: a-Si TFT-LCD, CELL
Diagonal size: 19.0 inch
Resolution: 1440x900, WXGA +
Display Mode: TN, Normally White, Transmissive
Active Area: 408.24x255.15 mm
Surface: Antiglare (Haze 25%), Hard coating (3H)
Transmissivity: 5.6% (with Polarizer)
Contrast Ratio: 1000: 1
Display Colors: 16.7M (8-bit)
Response Time: 1.5 / 3.5 (Tr / Td)
Frequency: 60Hz
Signal Interface: LVDS (2 ch, 8-bit), 30 pins
Voltage: 5.0V

BBK LT1904S LCD TV with M190A1-P0A LCD, 19 "(48 cm) diagonal 16:10 aspect ratio. 450 cd / m² screen brightness is provided by CCFL (EEFL) fluorescent lamps. Maximum brightness to minimum ratio (contrast) ) is 500: 1. You can view images in high quality HD at a resolution of 1440x900 pixels in the standard for graphic decomposition 720p (HD Ready). The input high-frequency or video signal can be processed in analog systems PAL, SECAM, NTSC. Graphic processing and digital signal generation occurs in standard max 480i, 480p, 576i, 576p, 720p, 1080i.
The power of the acoustic system of sound 6 W (2x3W) provide two speakers. The audio processing system NICAM STEREO is used.
The external interface (communication with other devices) is supported by standard input and output connectors: antenna input (RF), AV, audio x3, S-Video, component, SCART, RGB, VGA, HDMI. An output for connecting headphones is provided. To connect a computer or laptop to this TV model, a VGA (D-Sub 15) connector is used on the TV case, this interface supports resolutions: 640x480, 800x600, 1024x768, 1280x1024, 1360x768.
The power consumed by the TV in the operating mode from the network is 48 watts.
Overall dimensions: 573x372x171 mm.
TV Weight: 5.5 kg.
Attention! The BBK LT1904S M190A1-P0A / PV190WTVM CD4H LCD TV panel is its most expensive component.
Avoid hitting the glass and exerting pressure on the screen to avoid permanent damage to the LCD panel!
Posted By: FRANK at 07:02
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