Magnesium alloy going rogue - Electricity and vibrations
#1
Hello guys,

I bought my PBP (Manjaro August batch) a month ago and, so far, I'm loving it (really expecting a steady ARM based Fedora though...). Few crashes and weird bugs, but that was also expected !

Today I encountered a much more worrying issue : Over the night, the battery, though the PBP was turned off around 80%, completely drained to 0 %. And when I charged it this morning using the original charger, I realised that rubbing my fingers along the back of the screen (as well as the back of the keyboard and the sides of the trackpad : i.e. every Magnesium alloy shell) lead to weird vibrations / very very light electric shocks in my hand, along with a really light sound...

These vibrations completely stop the moment I unplug the charger. Weirder : while connected to the power supply, the vibrations also stop if I stop "rubbing" : If my finger touch the shell without moving, nothing happens....

I'm completely lost on this one (I do not get electricity at all actually, never did). Few people seem to have experience the same problem with various laptops, but I did not found any clear explanation on the internet. Static electricity ? Battery stuff leaking ? Mental issues ??!?!!?

Could this lead to any issue with the PBP (hardware failing, data disappearing...) or myself (stronger electric shock....) ? Can I use a different-brand charger with a PBP (if something compatible exists) or is it gonna be a problem ?

I beg you to help, since I bore everyone to death with my Linux-based laptop since the very day it shipped. They'll really give me a hard time if it burns after 40 days... Please !


Thanks a lot !
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#2
First off: Don't worry, this is not dangerous. 

Yes, it's a pretty common effect on many unearthed power supplies. This will also happen with many cell phone chargers, especially powerful multi-port ones (5 port USB chargers, etc.). 

Power supplies today are switch-mode power supplies, which means they convert the mains AC to DC, convert this DC back to a high frequency AC and feed it into a smaller transformer (because of the higher frequency). This is not the full story (search for "flyback", "smps design", etc.)
These supplies have a (very) small amount of AC leakage current flowing from the mains to the output. 
Often there's a capacitor between the primary and secondary coil to reduce electromagnetic interference due to the high frequency switching. 
This capacitor will leak a bit of current (max. 100µA). There is also capacitive coupling between the transformer windings, depending on how the transformer is wound. 

In conclusion:
It's not dangerous, but a bit annoying.
You could use a different power supply (like one of the very high quality Lenovo USB-C laptop chargers, make sure to get one with earthing/3 pin plug!).
You could also plug another earth-referenced connection into the Pinebook, like an earthed monitor, earthed powered speakers, earthed powered USB hub, etc. 

So long,
Tobias
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#3
(10-03-2020, 08:59 AM)Timoun Wrote: Over the night, the battery, though the PBP was turned off around 80%, completely drained to 0 %.

You might wanna make sure you have the latest u-boot (search the wiki/forums if you're unsure what I mean) and the latest Manjaro kernel (I'm currently running 5.8.5) to have sleep working properly. Also check other threads in PBP forums about possible misalignment of the magnet in the lid that triggers the sensor - if you have yours misaligned your machine may not be going to sleep at all if you close the lid.
This message was created with 100% recycled electrons
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#4
Ok thanks, that is good news ! I will look for a more convenient power supply and check for the latest kernel and uboot (or maybe directly start with a try of Fedora on sd card…)

I’ll mark the thread as resolved, thanks again !
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