Nowadays, more and more monitor comes in with flyback transformers problems. Testing flyback transformers are not difficult if you carefully follow instruction. In many cases, flyback transformer can become short circuit after using not more than 2 years. This is partly due to bad design and low quality materials used during manufactures flyback transformer. The question is what kind of problems can be found in a flyback transformer and how to test and when to replace it. Here is an explanation that will help you to identify many flyback transformer problems. There are nine common problems can be found in a flyback transformer. a) A shorted turned in primary winding. b) An open or shorted internal capacitor in secondary section. c) Flyback Transformer becomes bulged or cracked. d) External arcing to ground. e) Internal arcing between windings. f) Shorted internal high voltage diode in secondary winding. g) Breakdown in focus / screen voltage divider causing blur display. h) Flyback Transformer breakdown at full operating voltage (breakdown when under load). i) Short circuit between primary and secondary winding.
Testing flyback transformer will be base on (a) and (b) since problem (c) is visible while problem (d) and (e) can be detected by hearing arcing sound generated by flyback transformer. Problem (f) can be checked with multimeter set to highest range measured from anode to ABL pin while (g) can be solved by adding a new monitor blur buster (For 14' & 15' monitor only.) Problem (h) can only be tested by substituting a known good similar Flyback Transformer. Different monitor have different type of flyback transformer design. Problem (i) can be checked using an ohm meter measuring between primary and secondary winding. A shorted turned or open in secondary winding is very uncommon.
What type of symptoms will appear if there is a shorted turned in primary winding? a) No display (No high voltage). b) Power blink. c) B+ voltage drop. d) Horizontal output transistor will get very hot and later become shorted. e) Along B+ line components will spoilt. Example:- secondary diode UF5404 and B+ FET IRF630. f) Sometimes it will cause power section to blow.
What type of symptoms will appear if a capacitor is open or shorted in a flyback transformer?
a. No display (No high voltage). b. B+ voltage drop. c. Secondary diode (UF5404) will burned or shorted. d. Horizontal output transistor will get shorted. e. Power blink. f. Sometimes power section will blow, for example: Raffles 15 inch monitor. g. Power section shut down for example: Compaq V55, Samtron 4bi monitor. h. Sometimes automatic brightness limiter (ABL) circuitry components will get burned. This circuit is usually located beside flyback transformer. For example: LG520si