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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All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Tuesday, 24 March 2020

REPAIR / SERVICING TV BBK LED1975

Technical description and composition of the BBK LED1975 TV, panel type and applicable modules. The composition of the modules.
BBK LED
Model: LED1975
Chassis / Version: S191Z4DNRJ2WB
Panel: E185SG03 Rev01
LED driver (backlight): integrated into PSU
PWM LED driver: FTT1251 (8) BIT1251
Trans LED driver: SKY470
Power Supply (PSU): CEM-1
PWM Power: PWM SOT23-6
MainBoard: 88XR-MCEZ4D01975
IC MainBoard: DVD SY02 120X
Control: RC-LED101, RC-LED2012
Technical Specifications LED1975DT
BBK LED1975
General repair guidelines for TV LCD LED
Possible malfunctions
- The BBK LED1975 TV does not turn on and does not show any signs of turning on. There are no reactions to the control buttons or the remote control.
Typically, with such manifestations, the defect is caused by faulty elements in the CEM-1 main power module. 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 a 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 switch may also be PWM PWM SOT23-6. It is checked only by replacement with a known good one.
- 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.
Usually in such cases, a malfunction is detected in the backlight nodes of the LED panel. The reason can be both in the power of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
It should be remembered that it is not possible to determine the open circuit in the LED lines without disassembling the panels with a tester or multimeter without an additional device, for example, a current source. To open all PN junctions connected in series at once, a voltage of several tens of volts may be required. Then it is necessary to open the panel and check each LED separately with a multimeter. If the capabilities of your multimeter do not allow you to open the LED in the forward direction or dual LEd are used, then the PN junction of the emergency zener diode can indirectly serve as a health indicator. In case of LED-a failure, the zener diode PN junction will either be cut off or broken into short-circuit.
- The TV does not turn on, the indicator indicates standby or operating mode, or blinks.
Repair or diagnostics of the 88XR-MCEZ4D01975 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). Complex repair of MB (SSB) is possible only in the conditions of a service center with the necessary equipment. Testing or replacing DVD SY02 120X DVD components requires the necessary training and professional skills to repair modules at the component level. Problems associated with the use of BGA soldering technologies can sometimes be diagnosed by warming up.

Attention! For users and owners of LED1975 TVs who do not have the appropriate qualifications, knowledge and experience, we categorically do not recommend attempting self-repair in order to avoid negative consequences that could lead to complete non-repairability of the device.
SCHEMATIC DIAGRAM  / SERVICE MANUAL   ------------------>    BBK LED1975, LED2275F, LED2475F, LEM1988, LEM2288F, LEM2488F (MST6M182VG + 2IN1 POWER SUPPLY)

 Main features of the BBK LED1975 device:
Installed matrix (LED panel) E185SG03 Rev01.
To power the backlight LEDs, a converter is used, combined with the power supply, it is controlled by the FTT1251 (8) BIT1251 PWM controller. The SKY470 transformer is installed in the LED driver converter.
The necessary supply voltages for all nodes of the TV BBK LED1975 are generated by the CEM-1 power module or its analogs using PWM SOT23-6 microcircuits.
MainBoard - the main board (motherboard) is a 88XR-MCEZ4D01975 module, using DVD SY02 120X chips and others.
Posted By: FRANK at 05:50
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