Power Supply Blow Again After Sometime

If you have replaced power components (be it a power IC or power FET) and the power supply blow again after sometime, then i suggest that you check on the secondary side. The secondary side that I’m referring to is the legs of the power transformer. I came across the power transformer secondary pins that had intermittent dry joints problem and the power supply could work (may be few hours ) but after that it will blow again. It is interesting to know that the blown parts were exactly the one that were replaced earlier. It will cause overvoltage, because no load at the secondary side. This tiny dry joints were quite hard to see and if possible get a magnifying glass to help you out.

Sometimes it can be your fault too because you did not apply the heat compound to the power IC (power IC that attach to heatsink) or even to the power FET. Always check corresponding components if you found that the power FET had shorted