Tag: 2cl71

Monitor No Display – How To Repair Likom No High Voltage Problem

The criticism for this particular LIKOM 1-5″ L4031NDG keep an eye on wasn’t any display also it has electrical power. No display is no large voltage, collapse in G1, G2 and furnace circuit, faulty flyback transformer, collapse in film tubing along with micro-processor or even several different explanations. As a way to learn the clear answer we must modify about the keep track of. Up on shifting to the screen, it wasn’t possible for me to hear some noise from your screen however, also the energy generated is on (green light). You can not feel some static in the glass of this tube. This might possibly be an indication of no high-voltage manifestation.

Anyhow, I must utilize my loyal Kaise SK9000 top ion probe to assess whether the top voltage gift in the anode. Some times in the event that you fail to have that the inactive in the glass of CRT, does not follow the superior voltage isn’t existing. It truly is just lower in high-voltage; state may possibly be 10 to 1-2 kilo-volts. Low top voltage and also no premium voltage are wholly two symptoms. From the aforementioned scenario, my elevated voltage probe enrolled zero dioxide! Therefore it has affirmed no high-voltage issue.

You’ll find more than a few known reasons for no high-voltage issue. A lost Bvoltage, a faulty flyback transformer, no flat driveway heartbeat from h/v oscillator ic, missing or low distribution voltage into flat driver transformer and could trigger no high-voltage. The very first point I have assessed is that the fly-back inner capacitor-the capacitance is over the conventional scope that’s 2.7 nanofarad. In the event the interior capacitor is shorted, then it would induce no high-voltage. The 2nd thing I have assessed to become fine is that the Bvoltage 2cl71. It revealed about fifty + liter and this also implies there’s distribution going into the Bpin of flyback transformer.

After assessing the 3rd position (the voltage in the first twisting of flat flyback transformer)I found it has zero wattage that’s very odd. The bottom drive strength distribution input has approximately 14 horsepower but following the resistor it revealed zero wattage (by suitable it will consume roughly 1 2 volt-voltage decline right after the resistor). As soon as I set my finger over the bottom drive electrical power resistor only after shifting off the keep an eye on, ” I really could believed that it had been hot. This really is that which we predict a hint. Even a fantastic functioning base travel electrical power resistor wont find sexy until it burns off your own finger! There has to be a thing which moved inappropriate or shorted which gets the ability resistor turned exceptionally sexy. By the end we receive we are able to express the flat push circuit is needing difficulty that my focus is really about this circuit.

A shorted flat driver transformer main winding, flat driver transistor, parts encircling this particular circuit can create the ability resistor to become alluring. The flat driver transformer primary twisting could be assess using a dick smith fly-back tester as the flat driver transistor and encircling components might be evaluation with an ordinary multi meter. The end result, astonishingly much one component inside this circuit saw to be defective.

Since it wasn’t possible for me to find the faulty parts, the single means to learn to blame will be to come back out together with my very own drawing foundation onto the screen circuit (making use of track circuit concept to clear up trouble ).

After the screen is switched to the h/v oscillator tda4858 is going to get a source voltage around 912 liter from electricity source. Subsequently it may ship a square wave heartbeat into flat driver transistor as a result of snare 7 (flat motorist output) to induce the transistor to modify. The moment the flat motorist is shifting the flat driver transformer works and also an base sign has been generated to switch to the horizontal output transistor (warm ). This very hot would subsequently drive the flyback transformer and 2 4 kilovolt would look in the anode.

I questioned me exactly what should the h/v oscillator ic tda4858 rather than providing a square heartbeat, it develop a more continuing sign? In case it sends a continuing five liter sign into the horizontal driver transistor, then that transistor wouldn’t swap and inducing it to twist”to” all of the moment; point. In case that transpire, the bottom drive electrical power resistor along with also the flat driver transformer main twisting could undergo. The bottom driveway electrical power resistor along with also the horizontal driver transformer main winding today might behaves exactly enjoy a filament or perhaps a lamp! . No ramble the bottom drive electrical power resistor was becoming hot once the screen was switched .

Once attentively learned the flat drive circuit, then I have left in decision it had been the h/v oscillator tda4848 that transmits out a incorrect signal evoking the bottom driveway electricity resistor to receive sexy and in an identical time inducing no high-voltage at the track. I used to not utilize an oscilloscope to check on to your square tide so as to demonstrate my concept accurately because I am very sure it had been that the h/v oscillator IC which output wrong sign that led to no elevated voltage.