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Article Check - Monitor No Display - How To Repair Likom No High Voltage Problem
Learn how to sell your property faster and at the best possible price. Selling your property quickly and at the highest price is the target for everyone looking to move. However, the reality can be quite different so it is important to give yourself the maximum opportunity to achieve both of these goals.Image you are on the search for your perfect new home. Are you more likely to be interested in a property that is well presented, neutral colours throughout, and free of clutter with a tidy garden, or a property that is looking rather tired, with a collection of bright differently coloured uncoordinated rooms with floral carpeting alongside plenty of clutter? For some, the idea of a big DIY proje
You would not believe this; yes it was this culprit (TDA4858) that caused the monitor no display problem. After replacing the IC, the high voltage immediately energized and the zero volts measured at the pin of horizontal driver transformer now showed 12 volts! What a relieved and a great satisfaction in my heart. I believe if we continue to switch on the Monitor for a longer period, either the base drive power resistor or the horizontal driver transformer primary winding would burnt out causing it to open circuit.
Repairing Monitors need patience, understanding how Monitor work and its signal and also the right way to test electronic components. If the practical way can’t solve a problem, you can alwa
Have you often thought of starting your own business but you just don't know what kind of business to start? You are not alone. Many people are often confused when examining all of the different types of businesses there are to choose from. Let me give you a few examples.First we have the traditional "mom and pop" type businesses. These are generally the smaller retail type of businesses that you find on the street. The sad part is that most of these businesses fail in 5 years. The reasons are often due to poor management in one or more of the areas that make up the business. Examples are accounting, management, advertising and purchasing.Another type of business with a higher success
Anyhow, I have to use my faithful Kaise SK9000 high voltage probe to check if the high voltage present at the anode. Sometimes if you can’t feel the static at the glass of CRT, doesn’t mean that the high voltage is not present. It’s only low in high voltage; say may be 10 to 12 kilovolts. Low high voltage and no high voltage are totally two different symptoms. In the above case, my high voltage probe registered zero volts! So it’s confirmed no high voltage problem.
There are many reasons for no high voltage problem. A missing B+ voltage, a defective flyback transformer, no horizontal drive pulse from h/v oscillator ic, low or missing supply voltage to horizontal driver transformer and etc could cause no high voltage. The first point that I have checked was the flyback internal capacitor-the capacitance is within the normal range which is 2.7 nanofarad. If the internal capacitor is shorted, it would cause no high voltage. The second point that I have checked to be okay was the B+ voltage. It showed about 50 + volts and this mean there is supply entering the B+ pin of flyback transformer.
When checking the third point (the voltage at the primary winding of horizontal flyback transformer), I found that it has zero volt which is very unusual. The base drive power supply input has about 14 volts but after the resistor it showed zero volts (by right it should have about 12 volt-voltage drop after the resistor). When I placed my finger on the base drive power resistor just after switching off the Monitor, I could felt it was very hot. Now this is what we call a clue. A good working base drive power resistor won’t get hot till it burns your finger! There must be something that has gone wrong or shorted that makes the power resistor turned extremely hot. From the result we get, we can say that the horizontal drive circuit is having problem so my concentration is on this circuit.
A shorted horizontal driver transformer primary winding, horizontal driver transistor, components surrounding this circuit could cause the power resistor to turn hot. The horizontal driver transformer primary winding can be check by using a dick smith flyback tester while the horizontal driver transistor and surrounding components can be test with a normal multimeter. The result, surprisingly not even one component in this circuit found to be faulty.
Since I could not locate the defective components, the only way to find out the culprit is to come out with my own schematic drawing base on this monitor circuit (using monitor circuit theory to solve problem).
When the monitor is turned on the h/v oscillator tda4858 will receive a supply voltage about 9-12 volts from power supply. Then it will send a square wave pulse to horizontal driver transistor through pin 7 (horizontal driver output) to cause the transistor to switch. Once the horizontal driver is switching the horizontal driver transformer would work and a base signal was produced to turn on the Horizontal output transistor (HOT). This HOT would then drive the flyback transformer and 24 kilovolt would appear at the anode.
I asked myself what if the h/v oscillator ic tda4858 instead of producing a square pulse, it produce a constant signal? If it sends out a constant 5 volts signal to the horizontal driver transistor, then this transistor would not switch and causing it to turn “on” all the time. If this happen, the base drive power resistor and the horizontal driver transformer primary winding would suffer. The base drive power resistor and the horizontal driver transformer primary winding now would acts just like a filament or a lamp!. No wander the base drive power resistor was getting hot when the monitor was turned on.
After carefully studied the horizontal drive circuit, I’ve made the conclusion that it was the h/v oscillator tda4848 that sends a wrong signal causing the base drive power resistor to get hot and at the same time causing no high voltage in the monitor. I did not use an oscilloscope to check for the square wave in order to prove my theory right because I’m very certain that it was the h/v oscillator IC that output a wrong signal that caused no high voltage.
You would not believe this; yes it was this culprit (TDA4858) that caused the monitor no display problem. After replacing the IC, the high voltage immediately energized and the zero volts measured at the pin of horizontal driver transformer now showed 12 volts! What a relieved and a great satisfaction in my heart. I believe if we continue to switch on the Monitor for a longer period, either the base drive power resistor or the horizontal driver transformer primary winding would burnt out causing it to open circuit.
Repairing Monitors need patience, understanding how Monitor work and its signal and also the right way to test electronic components. If the practical way can’t solve a problem, you can alway
One of the myths with online businesses is that you can start them without any investment. That is simply not true because every business requires some investment to start properly. The good thing about the internet is that you can start with a very low investment but do not expect this to be zero.The first place is your own home. Go through the garage, basement, closet and other locations looking for what you do not need. If something qualifies as junk then rethink it, maybe it is not junk to someone else. If something is worthless in your opinion you might still get a reasonably good price for it on eBay. This is perhaps the easiest way to make money using eBay. Always take a good picture of the i
When checking the third point (the voltage at the primary winding of horizontal flyback transformer), I found that it has zero volt which is very unusual. The base drive power supply input has about 14 volts but after the resistor it showed zero volts (by right it should have about 12 volt-voltage drop after the resistor). When I placed my finger on the base drive power resistor just after switching off the Monitor, I could felt it was very hot. Now this is what we call a clue. A good working base drive power resistor won’t get hot till it burns your finger! There must be something that has gone wrong or shorted that makes the power resistor turned extremely hot. From the result we get, we can say that the horizontal drive circuit is having problem so my concentration is on this circuit.
A shorted horizontal driver transformer primary winding, horizontal driver transistor, components surrounding this circuit could cause the power resistor to turn hot. The horizontal driver transformer primary winding can be check by using a dick smith flyback tester while the horizontal driver transistor and surrounding components can be test with a normal multimeter. The result, surprisingly not even one component in this circuit found to be faulty.
Since I could not locate the defective components, the only way to find out the culprit is to come out with my own schematic drawing base on this monitor circuit (using monitor circuit theory to solve problem).
When the monitor is turned on the h/v oscillator tda4858 will receive a supply voltage about 9-12 volts from power supply. Then it will send a square wave pulse to horizontal driver transistor through pin 7 (horizontal driver output) to cause the transistor to switch. Once the horizontal driver is switching the horizontal driver transformer would work and a base signal was produced to turn on the Horizontal output transistor (HOT). This HOT would then drive the flyback transformer and 24 kilovolt would appear at the anode.
I asked myself what if the h/v oscillator ic tda4858 instead of producing a square pulse, it produce a constant signal? If it sends out a constant 5 volts signal to the horizontal driver transistor, then this transistor would not switch and causing it to turn “on” all the time. If this happen, the base drive power resistor and the horizontal driver transformer primary winding would suffer. The base drive power resistor and the horizontal driver transformer primary winding now would acts just like a filament or a lamp!. No wander the base drive power resistor was getting hot when the monitor was turned on.
After carefully studied the horizontal drive circuit, I’ve made the conclusion that it was the h/v oscillator tda4848 that sends a wrong signal causing the base drive power resistor to get hot and at the same time causing no high voltage in the monitor. I did not use an oscilloscope to check for the square wave in order to prove my theory right because I’m very certain that it was the h/v oscillator IC that output a wrong signal that caused no high voltage.
You would not believe this; yes it was this culprit (TDA4858) that caused the monitor no display problem. After replacing the IC, the high voltage immediately energized and the zero volts measured at the pin of horizontal driver transformer now showed 12 volts! What a relieved and a great satisfaction in my heart. I believe if we continue to switch on the Monitor for a longer period, either the base drive power resistor or the horizontal driver transformer primary winding would burnt out causing it to open circuit.
Repairing Monitors need patience, understanding how Monitor work and its signal and also the right way to test electronic components. If the practical way can’t solve a problem, you can alwa
Electronic discovery is the process of locating and retrieving electronic data. These days, every company is storing its important information in the electronic format, in devices like CD ROMs, DVDs, hard disks, floppy disks, and others. Data is also being sent across the world in electronic formats via e-mail or Internet because of the speed and cost-effectiveness. However, this may cause some of the data to be lost or altered. Electronic discovery enables the retrieval of such electronic data from the vast amounts of data available. Another important application of electronic discovery is in litigation or lawsuits. Electronic discovery can even bring out electronic evidence that has been tampered with.’t get hot till it burns your finger! There must be something that has gone wrong or shorted that makes the power resistor turned extremely hot. From the result we get, we can say that the horizontal drive circuit is having problem so my concentration is on this circuit.
A shorted horizontal driver transformer primary winding, horizontal driver transistor, components surrounding this circuit could cause the power resistor to turn hot. The horizontal driver transformer primary winding can be check by using a dick smith flyback tester while the horizontal driver transistor and surrounding components can be test with a normal multimeter. The result, surprisingly not even one component in this circuit found to be faulty.
Since I could not locate the defective components, the only way to find out the culprit is to come out with my own schematic drawing base on this monitor circuit (using monitor circuit theory to solve problem).
When the monitor is turned on the h/v oscillator tda4858 will receive a supply voltage about 9-12 volts from power supply. Then it will send a square wave pulse to horizontal driver transistor through pin 7 (horizontal driver output) to cause the transistor to switch. Once the horizontal driver is switching the horizontal driver transformer would work and a base signal was produced to turn on the Horizontal output transistor (HOT). This HOT would then drive the flyback transformer and 24 kilovolt would appear at the anode.
I asked myself what if the h/v oscillator ic tda4858 instead of producing a square pulse, it produce a constant signal? If it sends out a constant 5 volts signal to the horizontal driver transistor, then this transistor would not switch and causing it to turn “on” all the time. If this happen, the base drive power resistor and the horizontal driver transformer primary winding would suffer. The base drive power resistor and the horizontal driver transformer primary winding now would acts just like a filament or a lamp!. No wander the base drive power resistor was getting hot when the monitor was turned on.
After carefully studied the horizontal drive circuit, I’ve made the conclusion that it was the h/v oscillator tda4848 that sends a wrong signal causing the base drive power resistor to get hot and at the same time causing no high voltage in the monitor. I did not use an oscilloscope to check for the square wave in order to prove my theory right because I’m very certain that it was the h/v oscillator IC that output a wrong signal that caused no high voltage.
You would not believe this; yes it was this culprit (TDA4858) that caused the monitor no display problem. After replacing the IC, the high voltage immediately energized and the zero volts measured at the pin of horizontal driver transformer now showed 12 volts! What a relieved and a great satisfaction in my heart. I believe if we continue to switch on the Monitor for a longer period, either the base drive power resistor or the horizontal driver transformer primary winding would burnt out causing it to open circuit.
Repairing Monitors need patience, understanding how Monitor work and its signal and also the right way to test electronic components. If the practical way can’t solve a problem, you can alwa
IntroductionLast Christmas I saw an advertisement for the Paid Online Surveys home business opportunity. The ad talked about earning up to $125 for a survey and $150 for focus groups. I could not believe what I read…wow… can earning a side income really be that easy? The mathematician in me got the calculator out and started doing the sums. Prudently, I worked out the average payment of a survey at $50 and $100 for a focus group (down from the quoted amounts to allow for ad embellishment) and… Voila …just two of these surveys a day and some focus groups over the weekend would bring me in about $50,000 a year.At that moment I was jumping for joy. Alas, I had found what I was looking fo
I asked myself what if the h/v oscillator ic tda4858 instead of producing a square pulse, it produce a constant signal? If it sends out a constant 5 volts signal to the horizontal driver transistor, then this transistor would not switch and causing it to turn “on” all the time. If this happen, the base drive power resistor and the horizontal driver transformer primary winding would suffer. The base drive power resistor and the horizontal driver transformer primary winding now would acts just like a filament or a lamp!. No wander the base drive power resistor was getting hot when the monitor was turned on.
After carefully studied the horizontal drive circuit, I’ve made the conclusion that it was the h/v oscillator tda4848 that sends a wrong signal causing the base drive power resistor to get hot and at the same time causing no high voltage in the monitor. I did not use an oscilloscope to check for the square wave in order to prove my theory right because I’m very certain that it was the h/v oscillator IC that output a wrong signal that caused no high voltage.
You would not believe this; yes it was this culprit (TDA4858) that caused the monitor no display problem. After replacing the IC, the high voltage immediately energized and the zero volts measured at the pin of horizontal driver transformer now showed 12 volts! What a relieved and a great satisfaction in my heart. I believe if we continue to switch on the Monitor for a longer period, either the base drive power resistor or the horizontal driver transformer primary winding would burnt out causing it to open circuit.
Repairing Monitors need patience, understanding how Monitor work and its signal and also the right way to test electronic components. If the practical way can’t solve a problem, you can alwa
Are you running or thinking about running a home business? If so, then you need to be sure that you are doing it right. Running a home business does not have to be hard, but it can be if you do not take the time to make sure that things are operating as they should be. Here are some do’s and don’ts of running your own home based business:Do: Know Your Passions - Before you start your home business, make sure it is something you like to do. Stick with your interests. While you may see people making a lot of money in certain fields, you may not enjoy those home business concepts as much. You will be much more successful if you do what you love.Do: Know If You Need Education - When you a
You would not believe this; yes it was this culprit (TDA4858) that caused the monitor no display problem. After replacing the IC, the high voltage immediately energized and the zero volts measured at the pin of horizontal driver transformer now showed 12 volts! What a relieved and a great satisfaction in my heart. I believe if we continue to switch on the Monitor for a longer period, either the base drive power resistor or the horizontal driver transformer primary winding would burnt out causing it to open circuit.
Repairing Monitors need patience, understanding how Monitor work and its signal and also the right way to test electronic components. If the practical way can’t solve a problem, you can always use the theory way to help you out. Thus it is important to know on how to read a monitor schematic diagram. Don’t give up and continue to learn and I believe one day you shall achieved what’s desired in your heart! Have a good day!
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