Delete comment from: Ken Shirriff's blog
The most often failure mode of those cheap fake chargers is breakthrough of the switching MOSFET because of either underrated MOSFET, poorly engineered snubbers and/or inadequate filthering of voltage spikes from the mains. When this happens, the core fully saturates, then fuse blows, primary is freewheeling and full magnetic field stored in the core is dumped into the secondary side, generating a short overvoltage peak that could theoretically get to the macbook, but is usually dampened in output caps and cable inductance.
The real danger of those chargers is inadequate insulation between primary and secondary side: either the clearance on the PCB, or mechanical construction, or poorly made flyback "transformer" - which I consider most dangerous as it is hard to get checked without using special equipment - a megger. Loosing MBA is nothing in comparison with loosing a life.
Apr 7, 2016, 11:55:55 AM
Posted to Counterfeit Macbook charger teardown: convincing outside but dangerous inside