The last article I referenced about electrolytic capacitor breakdown when under load. In this article I will discuss the high voltage sap covered ceramic circle capacitor. In PC screen, it is incessant utilized in the screen voltage (G2) line at the crt board. At the point when it fizzles, it can cause unpredictable or irregularly raster splendid and faint and once in a while no showcase.
Changing the flyback transformer screen control won’t tackle this issue. You can segregate the issue as whether in the event that it cause by an inadequate fly back or G2 line at crt load up. Eliminate the G2 wire from circuit and measure the screen voltage with a computerized multimeter-it ought to have a steady voltage (won’t change). In the event that the voltage isn’t steady presume the fly back. In the event that it OK, follow the screen voltage circuit. Typically this circuit comprise of just resistors and 2cl2FL s. Some of the time a blemished crt attachment may cause this kind of issue moreover!
Ordinarily a tech can’t address this irregular or no presentation issue is on the grounds that their computerized capacitance and ohmmeter estimated OK on the capacitors. The capacitors in the screen voltage line are generally appraised of 102,103, and 472 1kv to 2kv. A ‘missed’ in checking this capacitors will caused the professional can’t take care of the issue, except if he direct supplant the capacitor. An irregular capacitor can pull down the screen voltage causing the presentation issue.
As referenced before, an ohmmeter with 12v yield and a computerized capacitance with 3v yield can’t precisely check the capacitor that have the rating of 1-2 kilovolt!
In the event that you have the simple protection analyzer or meter, the board will show a short out when certain voltage are siphon in to check the high voltage capacitor. The voltages that you can choose is relies upon the brand or model you purchase. Some have the scope of 50v to 1000v and some have the reach from 100v to 500v. It is discretionary whether you ought to have one. In the event that you have one, it would be an additional benefit for you. The other alternative that you have is to coordinate supplant the presumed capacitor. In my country, you can get another one in under US150.00 or you may offer a pre-owned unit from eBay.
With respect to me, checking the little blue gum covered clay circle capacitor that have the capacitor code of 104 50v, other than utilizing computerized capacitance meter to check for the worth, I additionally utilize a simple meter set to times 10Kohm that have the yield of 12v to check this sort of capacitor. Commonly it will uncovered the awful irregular capacitor. You will be stunned to see the capacitance meter checked OK yet show a shorted perusing when check with simple multimeter.
In the market there is sure brand of simple multimeter that have the scope of 100kohm. On the off chance that you open up the cover, you can’t see the 9v battery in it, what you see just the 2 bits of 1.5v battery. This sort of meter can’t precisely distinguish the short in the capacitor on the grounds that the yield voltage is just 3volt!
For those of you who associated with fixing screen, you will concur with me that checking the flyback interior capacitance-regularly you get the correct worth 2.7nf with computerized capacitance meter however when you switch on the screen, you will hear a ‘tick-tick’ sound from the flyback. This is on the grounds that the capacitor is separating when under load. On the off chance that you didn’t do anything with the flyback, steadily the interior capacitance will get shorted and you should repair the flyback.