My old sony cfs-kw250s stereo cassette player got damaged after turning the voltage selector switch from 220v to 110v . I want to know what problem it could have caused. I had tried changing fuse at the power points but it still doesn't function. I want to know if I have to replace the transformer or can it be repaired?
by doing that you doubled the supply voltage to the circuit board.
If it was only like this for a short time the likelihood is that the transformer survived.
However there is a high chance that this may have destroyed some components on the circuit board,it is not possible to say which ones without fully testing the board.
It could probably be repaired but due to the amount of fault finding and testing it may cost more than the cassette is worth.