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 24 February 2020

INVERTER / CONVERTER = 12V / ~ 220V

The converter is designed to power various low-power equipment for alternating current 220V from an automotive power source.
The frequency of the alternating current at the output is close to 50 Hz. The output voltage is not stabilized, but it can be controlled with a multimeter and regulated with a variable resistor.
Power of loading no more than 100W.
The diagram is shown in the figure. It is based on the TL594 microcircuit designed for operation in switching power supplies with a push-pull output and pulse-width regulation / voltage stabilization.


The equivalent generation frequency is 50 Hz, it is set by the resistance of the resistor R5, and depends on this resistance and the capacitance of the capacitor C5.
Resistor R4 controls the duty cycle of the output pulses. They can adjust the output voltage.
The outputs of the microcircuit are outputs 9 and 10, antiphase pulses are allocated to them, slightly delayed relative to each other so as not to cause a through current in the output stage circuit at the time of switching. Pulses arrive at the powerful key field-effect transistors VT1 and VT2 . Diodes VD2 and VD3 protect these transistors from negative EMF emissions on the primary winding of a pulse transformer T1.
The T1 transformer is a ready-made low-frequency power transformer with a rated power of 100W, with one primary winding at 220V and a secondary winding at 18V with a tap from the middle. You can try a transformer with a secondary winding of 12V with a tap from the middle or 24V with a tap from the middle. But, in the second case, I'm afraid that the output voltage will be slightly less than 220V.
The transformer is turned on “back to front”, that is, its secondary low-voltage winding now serves as the primary, and the high-voltage primary, as the secondary.
By connecting the load and a multimeter (or another AC voltmeter) with the resistor R4, set the voltage to the load 220V.
Author: V. Teplyakov