Robust Power Supplies
Some design of switch mode power supplies are so robust. They used good components and the circuit boards are thick and the circuit track are not easily break even after you have done some soldering/desoldering on the same point. I have came across quite number of equipment SMPS and I found that the Dot matrix printer (Panasonic, Epson and even NEC) power supplies are the best. They rarely fail (made in Japan) and most of the time were due to mainboard or other parts problem like sensors and print heads. Even the electrolytic caps found in these power supplies boards hardly have problem.
There are advantage and disadvantage of having a good design of Power supplies.
Advantage to Consumers:
1) Long lasting
Disadvantage to repairman:
1) Hardly breakdown thus less repair work
This is why sometimes we have to thank those manufacturers that have produced a not so good design of power supplies or even circuit boards. Just imagine every circuit boards could last more than 10 to 20 years then the repairman may have to close shop because less or no work for them to repair.