Agreed - SMPS supplies are tricky to fix unless you're an EE and as mentioned, it's often cheaper and easier to replace it.
Determining the failure mode could be worthwhile - look for obvious component overheating on the PCB or components - you also need to replace like-for-like, i.e. a replacement SMPS needs to be as good or higher spec than the original.
There is a world of difference in quality & noise between a cheap and a good SMPS - don't get the cheapest - get the best quality you can afford for your job - "budget" can be good if you're lucky and positively dangerous if not.
I designed a few low-noise SMPS supplies and it's not for the faint-hearted - to debug them you need experience and decent test kit - they also tend to have rectified mains AC inputs, so you can have about 320V DC lurking on the board (that's why there are 400V caps there) - a 320V zap from an electrolytic cap can really sting. Just be careful.
Last edited by nickds1; 24-07-2017 at 14:41.
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