Always Check Corresponding Components
Now in troubleshooting it is not always only one component that give problem. I used to receive email saying that they have found the bad component and after the replacement the power section or the HOT blow again. In certain electronic problems, there are usually few bad components that made a section malfunction. That means just by replacing a bad components would not solve the problem. One must check for other components too.
For example, if you found that the power FET had shorted don’t get excited and straight away replace the power FET and turn on the equipment. Chances is very high the new replacement of the power FET would blow again. Actually if you found a bad component in the power side (shorted FET), your next step would be to make sure all other corresponding components are good which include the primary winding of power transformer and also the secondary side diodes. If you have check all of the components then finally you can turn on the equipment but again please connect a light bulb in series with the mainline so that if there is still problem in the smps the components that you have replaced would not blow again due to the current have been limit by the light bulb.