Here's a good Diagnostic Tear Down - How To Video. On a Bad USB Hub, by bigclivedotcom. "USB ports have carried full mains current. (via a rectifier). It's a Swees QY08-05010 with this model and style carrying various other branding as well. Oddly it does appear to be relatively sensibly designed inside, but this one has a serious manufacturing fault that suggests others from the same run may also pose a risk of serious electric shock." Check out the Related videos too...

Don

Horrific USB power supply fault. (Electrocution risk.)

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Video link...
https://www.youtube.com/watch?v=3Hdn0MuCK_0

Published on Apr 4, 2016

Although I've come across some really dodgy power supplies with poor insulation between the mains and low voltage sides, this is the first one where the USB ports have carried full mains current. (via a rectifier)
It's a Swees QY08-05010 with this model and style carrying various other branding as well. Oddly it does appear to be relatively sensibly designed inside, but this one has a serious manufacturing fault that suggests others from the same run may also pose a risk of serious electric shock.

Sadly, this just reinforces my doubts about the poor separation in many of these small transformers. I'd rather have split bobbin transformers even if it meant efficiency taking a slight hit.

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