So I am dismantling and ripping into a cheap Chinese counterfeit phone charger and revealing all that I see wrong with it. One thing I could do with some insight into though is the purpose of a resistor.
It is basically a 3.3Ω resistor which is in series with the mains (240V) input into the bridge rectifier:
What are they trying to achieve there?
(Mind, given the state of the rest of the circuit maybe even the designers don't know?)
Should it in fact have been a fuse?
Best Answer
Some resistors are designed so that they will fail open when they overheat. An advantage of such resistors versus fuses is that when failure is a result of an output short-circuit, the resistor will limit how much current will pass in the time it takes to blow. With 120V mains (170V peak) the peak current would be about 50 amps, which is rather a lot, but is still much less than would be able to pass through a "normal" fuse.