Sister has got a Samsung RC520 laptop. And this laptop power supply has got some functionality problems since bought. From time to time it stopped charging laptop and green LED light in adapter case went off. Than it was discovered that pulling off mains plug and plugging back in socket resolves issue. But unfortunately problem got more sever and after a while this procedure above did not help anymore. As the warranty period was over I decided to try to repair it.
AC adapter model name is CPA09-004A and it is made by Chicony Power Technology company. While opening adapter plastic case with knife I was thinking about possible problems what could made such fault symptoms. I was suspecting some loose soldering connection or something else but easy to fix. After opening and removing shields and rubbing away glue spots first thing I noticed was missing solder on one side of zero ohm resistor.
|Red arrow shows resistor pad which is missing solder|
It is always good to start electronic equipment repair with close look and inspection of device. It can save a lot of time.
So this situation with partly soldered part of course was suspicious already. After closer look it shows that resistor is series connected with optocoupler. And it explains device fault symptoms. When resistor looses connection than PWM driver are not getting feedback signal and shuts itself down. Removing and reapplying mains voltage restarts driver IC.
Than I properly soldered the resistor and connected the power supply to mains. And problem was gone of course. It can be seen also by looking on green LED which was steady and bright.
I don't know how likely is that somebody of you can meet the exact same problem on your AC adapter, but it tells something about Chicony manufacturing quality control. If you have the same product and it needs repair start with close visual inspection and look for loose connections, solder joints and similar easy things first.
And remember to be cautious when connecting power supply PCB to mains voltage without enclosure, because it is dangerous. If you are not sure what are you doing better leave repair to electronics repair service professionals.