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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Wednesday, 27 February 2019

EDUCATIONAL GAME

Educational Game


This educational game project can be used in a quiz competition to see which of the participants press the button first to answer questions posed by the quiz master. This constructional project is based on a latch CD74HC75 IC and a 4 input CD74AC20 NAND IC. The first person to press the switch will light up the LED designated for the person. The rest of the LEDs will not be able to be activated until the RESET button is pressed.


The truth table of the Latch IC and the NAND IC is as shown in the figures below.


Schematic Diagram

Initially when RESET button is pressed, the output of NAND gate from U2A will be logic "0" as all the inputs are at logic "1"state. As shown in the truth table for NAND gate, when all the inputs are "1", its output will be "0". Hence the output of NAND gate from U2B will be logic "1" since an input of "0" will cause it to go to logic "1". The logic "1" to the latch indicates that it is ready to output any data once any of the button is pushed.
If the first button pushed is S1, the logic at its output 1Q will be logic "0" and caused LED1 to light up. At the same time,it caused the output of U2A to go into logic "1". Hence the output of U2B will be logic "0" causing the latch to be disable which means that the outputs of all the latches will be at their previous state. As a result, the player who pressed button S1 will be shown as the one who is first to press the button and so qualify to answer the question.
The RESET button will be pressed by the quiz master to prepare the circuit for the next game.

Parts List