DellDriverTM.com is a web-site that specialize on supplying Dell’s most recent Drivers both for Printers, Laptops, or even Screens. Get the most up-to-date Dell Drivers here from our web-site.
The complaint for this LIKOM 15″ L4031NDG Monitor was no show and has electric power. Nicely, no screen can be no large voltage, failure in G1, G2 and heater circuit, defective flyback transformer, failure in photo tube and microprocessor or a lot of other motives . In buy to uncover out the solution we have to change on the Monitor. Upon switching on the monitor, I could not listen to any seem from the monitor but the electric power led is on (green light). You can not experience any static at the glass of the photograph tube. This could be a indicator of no higher voltage symptom.
Anyhow, I have to use my devoted Kaise SK9000 high voltage probe to check out if the high voltage present at the anode. Often if you cannot truly feel the static at the glass of CRT, isn’t going to suggest that the superior voltage is not existing. It is really only minimal in large voltage say could be 10 to 12 kilovolts. Low high voltage and no significant voltage are absolutely two distinct indicators. In the over case, my significant voltage probe registered zero volts! So it is verified no significant voltage issue.
There are numerous explanations for no substantial voltage issue. A lacking B+ voltage, a faulty flyback transformer, no horizontal generate pulse from h/v oscillator ic, low or lacking source voltage to horizontal driver transformer and and so forth could result in no substantial voltage. The initial level that I have checked was the flyback internal capacitor-the capacitance is within just the usual range which is 2.7 nanofarad. If the interior capacitor is shorted, it would lead to no significant voltage. The second stage that I have checked to be all right was the B+ voltage. It showed about 50 + volts and this necessarily mean there is provide entering the B+ pin of flyback transformer.
When examining the 3rd stage (the voltage at the principal winding of horizontal flyback transformer), I discovered that it has zero volt which is quite unusual. The foundation travel energy source enter has about 14 volts but soon after the resistor it showed zero volts (by correct it should really have about 12 volt-voltage fall right after the resistor). When I put my finger on the foundation generate electricity resistor just after switching off the Monitor, I could felt it was extremely incredibly hot. Now this is what we contact a clue. A great operating base generate energy resistor would not get hot until it burns your finger! There need to be some thing that has gone improper or shorted that tends to make the power resistor turned really hot. From the consequence we get, we can say that the horizontal generate circuit is possessing problem so my concentration is on this circuit.
A shorted horizontal driver transformer main winding, horizontal driver transistor, elements bordering this circuit could bring about the ability resistor to change warm. The horizontal driver transformer primary winding can be verify by utilizing a dick smith flyback tester whilst the horizontal driver transistor and encompassing elements can be take a look at with a standard multimeter. The outcome, amazingly not even 1 part in this circuit found to be faulty.
Since I could not locate the defective parts, the only way to discover out the culprit is to come out with my individual schematic drawing base on this monitor circuit (utilizing monitor circuit idea to fix problem).
When the monitor is turned on the h/v oscillator tda4858 will get a provide voltage about 9-12 volts from electricity offer. Then it will ship a sq. wave pulse to horizontal driver transistor by pin 7 (horizontal driver output) to bring about the transistor to switch. As soon as the horizontal driver is switching the horizontal driver transformer would perform and a foundation sign was created to transform on the Horizontal output transistor (Hot). This Scorching would then drive the flyback transformer and 24 kilovolt would seem at the anode.
I requested myself what if the h/v oscillator ic tda4858 alternatively of developing a sq. pulse, it make a regular sign? If it sends out a frequent 5 volts signal to the horizontal driver transistor, then this transistor would not change and creating it to flip “on” all the time. If this occur, the foundation travel ability resistor and the horizontal driver transformer primary winding would experience. The foundation travel electricity resistor and the horizontal driver transformer most important winding now would acts just like a filament or a lamp!. No wander the base generate electricity resistor was obtaining very hot when the monitor was turned on.
Just after very carefully examined the horizontal generate circuit, I have designed the conclusion that it was the h/v oscillator tda4848 that sends a mistaken sign resulting in the base travel electrical power resistor to get sizzling and at the exact same time resulting in no superior voltage in the monitor. I did not use an oscilloscope to check for the sq. wave in order to confirm my concept ideal simply because I’m extremely specified that it was the h/v oscillator IC that output a erroneous sign that brought about no large voltage.
You would not believe that this sure it was this culprit (TDA4858) that caused the monitor no display trouble. Following changing the IC, the significant voltage immediately energized and the zero volts calculated at the pin of horizontal driver transformer now confirmed 12 volts! What a relieved and a excellent fulfillment in my coronary heart. I believe if we carry on to switch on the Monitor for a extended time period, possibly the base drive ability resistor or the horizontal driver transformer main winding would burnt out leading to it to open up circuit.
Repairing Monitors want persistence, being familiar with how Monitor operate and its sign and also the ideal way to take a look at digital components. If the useful way cannot resolve a difficulty, you can always use the principle way to enable you out. So it is significant to know on how to browse a monitor schematic diagram. Don’t give up and proceed to discover and I believe that a single day you shall realized what is actually wished-for in your heart! Have a superior day!
Download the Dell Drivers that you need to have from this download link