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a. High voltage shut down. b. Monitor will have ‘tic - tic’ sound. Sometimes capacitor may measure O.K. but break down when under full operating voltage. c. Horizontal output transistor will blow in a few hours or days after you have replaced it. d. Sometimes it will cause intermittent "no display". e. Distorted display i.e., display will go in and out. f. It will cause horizontal output transistor to become shorted and blow power section.
How to check if a primary winding is good or bad in a Flyback Transformer? a) By using a flyback/LOPT tester, this instrument identifies faults in primary winding by doing a ‘ring’ test. b) It can test winding even with only one shorted turned. c) This meter is handy and easy to use. d) Just simply connect probe to primary winding. e) The readout is a clear ‘bar graph’ display which show you if flyback transformer primary winding is good or shorted. f) The LOPT Tester also can be used to check CRT YOKE coil, B+ coil and switch mode power transformer winding.
NOTE: Measuring resistance winding of a flyback transformer, yoke coil, B+ coil and SMPS winding using a multimeter can MISLEAD a technician into believing that a shorted winding is good. This can waste his precious time and time is money.
How to diagnose if internal capacitor is open or shorted? By using a normal analog multimeter and a digital capacitance meter. A good capacitor have range from 1.5 nanofarad to 3 nanofarad.* 1) First set your multimeter to X10K range. 2) Place your probe to anode and cold ground. 3) You must remove anode cap in order to get a precise reading. 4) Cold ground means monitor chassis ground. 5) If needle of multimeter shows a low ohms reading, this mean internal capacitor is shorted. 6) If needle does not move at all, this doesn’t mean that capacitor is O.K. 7) You have to confirm this by using a digital capacitance meter which you can easily get one from local distributor. 8) If reading from digital capacitance meter shows 2.7nf, this mean capacitor is within range (O.K.). 9) And if reading showed 0.3nf, this mean capacitor is open. 10) You have three options if capacitor is open or shorted. - Install a new flyback transformer or - Send flyback transformer for refurbishing or - Send monitor back to customers after spending many hours and much effort on it.
* However certain monitors may have value of 4.5nf, 6nf and 7.2nf. Note: Sometimes internal capacitor pin is connected to circuits (feedback) instead of ground. Tv rca flyback transformer circuits usually do not have a internal capacitor in it. If you have a flyback diagram and circuits which you can get it from net, that would be an advantage to easily understand how to check them.
Jestine Yong is a electronic repairer and a writer. For more electronic repair articles please visit his website at http://www.noahtec.com/electronic-repair-articles.htm