ODroid HC2 Grounding Problem?

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RossenH
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ODroid HC2 Grounding Problem?

Unread post by RossenH » Mon Feb 26, 2018 6:00 am

Hey, guys. I just got a ODroid HC2. It's kind of a bummer that my first post in this forum is going to be an issue.

Anyways - yesterday I noticed that when I slide my finger on the side of the metal heatsink I feel a slight vibration. Like the unit is vibrating, but kinda different. It turned out it wasn't vibration at all but electricity - the same "vibration" can be felt when there is no drive or when the system is off, but plugged in. I don't have a multi meter to tell you the exact voltage. I did some research and it turns out that this is a grounding issue that is somewhat common with electronic devices made entirely or at least partially of aluminium / metal. It is especially common with some older Apple laptops. This video summarizes it very well (https://www.youtube.com/watch?v=3CtLchTMvD8). I also found that the effect can be noticed in some OnePlus models with aluminum unibodies. There are probably more examples and there are a quite a few forum posts describing exactly my issue. This probably wouldn't have been an issue if the power supply had three prongs like the one for the CloudShell 2.

My question with regards to the ODroid HC2 is - Is this normal? Have any of you guys experienced this? Maybe on the HC1 as well? To reproduce the issue - simply touching it is not enough, you need to slide or rub your finger slowly. It can be felt on the entirety of the metal heatsink and is stronger in the recessed part on the inner side - where the drive motor would fit. It doesn't hurt, but got me worried about several things. First could it be harmful to the Xu4 pcb inside or the SD card? Could it be harmful to the harddrive? Could it damage some other electronics in close proximity, like a USB drive. Probably would not be a good idea to leave it on a metal server rack or anything conductive.

I turned the system off right now, but before it was working for 48 hours non stop and there were no problems with it. Still I don't think this is normal. The opinions on the internet range from "this is normal" to "turn it of or you'll blow up" :D As obvious I don't know anything about electricity so what do you guys think?

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Re: ODroid HC2 Grounding Problem?

Unread post by odroid » Mon Feb 26, 2018 11:34 am

It looks normal.
I can also feel something electrical wave on the Aluminum heatsink surface of HC1/HC2 like my old Macbook.
We've been running several HC1 boards as a distributed storage system in our office over 6 months (24/7) and there is no stability issue so far.

We might need to check whether a well-grounded AC outlet can reduce the weird electrical feeling or not.

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Re: ODroid HC2 Grounding Problem?

Unread post by RossenH » Wed Feb 28, 2018 2:32 am

Thank you for your quick reply! I feel a bit better now. It is good to know that it is not just my unit. It is curious how nobody has brought this up before. Please keep us updated if you figure out something more on the topic.

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Re: ODroid HC2 Grounding Problem?

Unread post by Nox997 » Thu Dec 05, 2019 4:45 am

Hello!
I have a related problem on my odroid-hc2.
Without a hard disk installed, if I touch the metal heatsink / mounting case of the odroid, the HC2 will lock up (kernel led stops blinking, board is unresponsive).
Is it normal that a small static charge already influences the hc2 so much? Can this be avoided / improved?

Thank you very much in advance for your reply.

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Re: ODroid HC2 Grounding Problem?

Unread post by odroid » Thu Dec 05, 2019 10:30 am

When we tested the EMC/ESD test for the CE certification, HC2 could certainly pass 4KV contact and 8KV air discharging tests.
But we installed a HDD and used a grounded PSU with 220V AC. There was a plastic cover too.
So the test conditions might be different from your cases probably. Where do you live?

Anyway, it is interesting to estimate the voltage level from a finger in dry winter season.
https://physics.stackexchange.com/quest ... hal/244092

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Re: ODroid HC2 Grounding Problem?

Unread post by Nox997 » Fri Dec 06, 2019 2:17 pm

Thank you for the information!
Can the Odroid-hc2 be damaged from the static shock? How would I know?

Your mentioned a grounded power supply. I live in Germany and have a power supply with only two pins.

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Re: ODroid HC2 Grounding Problem?

Unread post by odroid » Fri Dec 06, 2019 3:03 pm

If the static electricity shock occurs for a very long period with very high voltage, it could happen.
But I have seen the issue only a couple of times while we've shipped over 10,000 ODROID boards every month from '2010.

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