Monitor Display Blur Problem
For those of you who repair CRT Monitors, i believe you had came across before of Monitors with display blur problem after “On” for sometime. The problem actually was caused by a defective flyback (focus/screen) divider in flyback transformer. After many years of service the internal material would breakdown and the heat slowly caused the high ohm resistance (usually 200 to 500 mega ohm) to change value. In order to check the internal resistance you really need a special meter that can check up to 1000 to 2000 mega ohm!
Due to the changing of the resistance value, the effect was that the output of the focus voltage may vary too! Normal focus voltage for a 14 and 15″ CRT Monitors is about 5 to 8 kilo volts and if the focus divider resistance value changed, suspect a bad focus divider. You can’t measure the focus voltage with a normal multimeter as it don’t have the capability to test voltage more than 1000 Volts. You have to use a high voltage probe to test the focus voltage.
A Monitor Blur Buster
Since a bad flyback divider can’t be replaced, the only thing you can do is to add in a Monitor Blur Buster. Some technicians prefers to add in an additional flyback transformer to solve the problem. You have to defeat the original focus and screen (G2) cable and use the focus/ screen cable from the Monitor blur buster. Before that, you must tap the high voltage from the original flyback transformer high tension cable which is located at the CRT anode. If you have no experience or do not know what I’m talking about , then please don’t do it as it involved high voltage. Take care and have a good and a fantastic day!