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My experience is the same. I recently pulled my x220 off the table onto a hard floor. My first thought was, "what an idiot!" My second thought was, "oh, it's a Thinkpad, nevermind". The laptop is obviously undamaged. (I will admit the display is rather flexible, but so are all Apple laptops. Gone are the days when you could run over your laptop with a car, sadly. I guess being so cheap that you can replace them without caring is better peace of mind than any magnesium roll cage.)

I am a qualified EE so will not comment on the initial article as it makes me squirm a bit.

I'm not, though I did take a lot of EE classes in college, and I think the article is fine. He took the thing apart and noted which components Apple used. He's not telling anyone how to engineer their own power supply.




I wouldn't say those days are gone. A buddy of mine accidentally ran over his MacBook pro a few years ago. Granted, it was in his backpack at the time, but still... that sucker just kept on trekking. Looked awful though. Bent the whole thing into a slight curve, pulled apart some of the seams, etc, but it still worked.


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There is no single fault that can cause short between primary side of transformer and the output connector casing, so it's OK. Also, isolation distances on orders of millimeters are relevant for open air or PCB breakdown (with PCB-air interface having lower breakdown voltage than air or PCB alone due to possible water condensation) and not for isolated wiring inside transformer. It's pretty hard to imagine any failure mode that would cause short between connector casing without also causing breakdown between transformer windings. The whole thing looks slightly over-engineered (L6565 seems to me as a bit of overkill for this application), but safe.

It's interesting to note that most cheap replacement chargers don't have significant safety issues but produce harmful EMI, on the other hand it's not too hard to find name brand power supply which have significant safety issues (eg. low impedance connection between otherwise unconnected ground of EMI filter on primary side and output ground), often caused by combination of safety, EMC and design/size requirements and weird interactions between them and between requirements of different jurisdictions (EMC, ESD and safety requirements of EU sometimes tend to be contradictory).


Note that many of the pictures don't include all the insulation. (I mention this in Footnote 5, so it's easy to miss.) In particular, there was a black plastic insulator over the USB output plug that only appears in the first picture. And there are several layers of insulating tape around the transformer. This should meet the safety standards; if it didn't, they wouldn't approve it after all.


UL didn't seem to mind. There is a lot of insulation between the primary and the USB socket: tape, plastic, the secondary winding, more tape, and so on. I can't imagine a failure mode for this system that would occur in normal use.


Tape melts, emits gas which is poisonous and is more conductive than the plain air gap. There's your failure mode.

Bear in mind my Airport express melted and blew my circuit breakers so shorts are definitely a possibility.


It also fails if subjected to a large amount of shrapnel!




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