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Likom 17" D1730LD Monitor Problem 

 

A repair friend of mine sent in a likom 17" monitor for me to repair and the complaint is horizontal output transistor-BU4523AX (HOT), modulation diode (31DF6) and damper diode (BY329X-1200) shorted after running for couple of days. He could not understand why the particular components blown after using for few days. This is the third repair when he sent it to my workshop and every time the same components burnt! He already checked all those important parts in the monitor such as the b+ line, flyback transformer, horizontal driver transformer area, secondary power section and even direct replaced most of the electrolytic capacitors. For your information, this repair friend of mine do not have esr meter-due to this he have to change all the electrolytic capacitors and took him a lot of time.

 

After the monitor cover had been removed I did not straight away change the suspected or spoilt components because I knew that if I replace all the bad components, the same problems will appear again after running for few days and you will be back to the square one. Instead, I carefully scan thru the board and hope to find the culprit first. I could not believe what I discovered, a tiny round of dry joint at one of the pin of flyback transformer. I believed my repair friend didn't take out the flyback transformer to check it entirely, he just checked the internal capacitance. In electronic repair sometimes we overlooked simple fault (which is dry joint) and try to locate or find any components that causing a problem. It is not necessary must be some major components faulty that cause big problem. It just take a tiny dry joint to make major destruction in any electronic equipments. Applied fresh solder and replaced the components solved the problem.

 

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