Problem: The moment I powered up the screen, the picture came on and then off. Then it started to come on and off very fast.
When the picture came on and off repeatedly, the standby power LED stayed on all the time. Which gave me the indication of bad back lights, bad capacitors or bad power supply? I opened the back cover of the LCD screen and the first thing I did was to check on the CCFL back lights. I used the CCFL tester LST01 to test the back light and to my surprise, all of CCFL tested fine.
I powered up the screen again and checked the voltage on the inverter IC and the 12 volts were there but not very steady. It was consistent with the screen coming on and off. What I mean is when the picture was on, I could see the 12 volts but when the picture was not there, the 12 volts are gone. I unplugged the screen from the main electricity out let and I took the PC board off. I scanned the whole area to see if there are bulged capacitors but there were none. I used the blue ESR meter to check the main capacitors and found two bad capacitors that had high ESR readings. One of them was 1000uf/25 volts and the other 220uf/35 volts. I replaced the two capacitors with new one and fired up the LCD screen. The volts on the inverter was steady but not for a long time. It was shutting on and off but this time it was slower than before.
I started checking the board for bad soldering joints. When I used the magnifying lens to do that, I found a lot of bad soldering joints. I re-soldered most of the power supply area and some in the high tension area. I powered up the LCD screen and checked for the 12 volts on the inverter IC. The 12 volts were steady and nice.
I put the LCD screen back together then, I powered up the screen. What a wonderful sight it was when I saw the picture on the LCD screen and this time, it stayed on. The colours were nice and the picture was clear. The LST01 is a good meter and it helped me to save testing time. Also the blue ESR meter was a good asset as well. I recommend these meters to anyone involved in electronics repair.