How To Repair Benq Fp731 17" LCD Monitor With No Power Symptom

The BenQ FP731 17” LCD Monitor came in with no power symptom. If you have read my previous articles, you would know that I would not immediate use all my testing gear to check the whole power and inverter board instead I would use my eyes to scan all the components first before starting to use my digital multimeter to check on the fuse and other components first.

I saw about 8 filter capacitors that had bulged and leaked on top of its capacitor casing. We have the first clue and if my assumption is right, only the capacitors that caused no power symptoms. However in order to be in the safe side we have to check other components as well.

Looking at the power primary side didn’t reveal any burnt or cracked components in the board. It is not good enough just by looking at the board, we must check few of the critical components first in order to confirm that it is safe to switch on the power after the replacement of the 8 faulty capacitors. The critical components that I referred to was the fuse, power or chopper fet (mosfet), switch mode power supply primary winding and secondary diodes. If you have the experienced, you can check all of the components on board without removing it but of course the smps primary winding you have to use a flyback tester to test it.

After all the critical components tested okay, I would presume that after the replacement of the defective capacitors, I could immediately switch on the LCD Monitor without connecting a light bulb first. There is no necessary to connect the light bulb because the power side components were tested okay besides the fuse didn’t blow in the first place.

For your information, most of the capacitors used in the LCD power supply were from the 105 degree Celsius in order to last longer and stand the heat produce by the power supply itself. If you replace with an 85 Celsius capacitor, it would not last long and may come back with capacitor problems again.

The Benq FP731 LCD Monitor was restored to normal operation after the 8 filter capacitors was replaced. Capacitors breakdown was very common in the LCD Monitor because of it compact design where the heat have difficulty to transfer out due to the power supply board was covered by an aluminum shielding. Sometimes after few hours of operation, you could feel the extreme heat at the aluminum shielding and surrounding area. This is a good news to us as an electronic repairer because more and more LCD Monitor send in for repair because of capacitors faults only.