Alix plus case - weird feeling



  • don’t laugh! i was just wondering if anybody had bought an alix plus case from linitx.com.
    the setup is running great but one thing intrigues me……
    when i rub my finger across the case when it’s off, it feels normal like any other case would.
    when i do it when it’s got power, it has a totally different feel to it.
    has anybody else experienced this or am i going mad?
    louis



  • You got to be picking up stray voltage in the case, that would explain the strange feeling.  Make sure the components in the case are grounded well.
    RC



  • i kinda thought it would be something to do with that but it isn’t giving me any kind of nasty shock or anything. you can sort of hear it buzz when you do it though!
    it’s just a standard install with the components supplied and working sweet as a nut! think i’ll contact the suppliers.



  • @louis-m:

    i kinda thought it would be something to do with that but it isn’t giving me any kind of nasty shock or anything. you can sort of hear it buzz when you do it though!
    it’s just a standard install with the components supplied and working sweet as a nut! think i’ll contact the suppliers.

    I won’t laugh at all  ;D I didn’t dare to post about this for obvious reasons but I have noticed EXACTLY the same. When you hold your finger still nothing happens but when you slide over the surface it feels like it vibrates a little. Very strange feeling.   ??? At least that makes 2 madmans now  😘

    Everything is installed the way it should be. Let me know if you have an update on this.



  • they have offered me an rma so I’m going to send it back for further investigation. my board is an alix 2d13 in the black enclosure. they say that nobody has ever experienced this before. i will keep you posted. I’d be interested to hear form other alix users as to whether they have experienced this.



  • It’s not much of an issue really.  The ground point alix isn’t anchored to mains earth because it uses a wallwart so you might feel a little bit of electric current flowing due to the potential differences (you’re technically grounded via your feet to “earth”)

    You can just use a piece of wire and wrap it around any of the screws on the alix on one end (strip the insulation first!).  Alternatively, using a screw on the serial port works as well.
    Connect the other end in a similar fashion to any other equipment that is grounded to mains earth (anything that uses a 3 prong plug).  If you don’t feel particularly comfortable with that idea, you can add a paralleled 0.1uF class-Y capacitor and 10 ohm/ 5W resistor in-line to form a ground-loop breaker.



  • dreamslacker…. how right you are. if i put one finger on the serial screw, the feeling stops which suggests it’s as you say. take the finger off and it’s back again.
    is there any problem with this? eg will it lessen the life of the alix, danger of a static shock etc?


  • Rebel Alliance Developer Netgate

    I don’t notice this on my ALIX, but it’s a board+case direct from PC Engines.

    That said, I do get very (very) slight readings on my multimeter when going from the case to another ground point that do not show up when both probes are on either the ALIX case itself or on the metal I’m calling ‘ground’ in this instance.



  • @louis-m:

    dreamslacker…. how right you are. if i put one finger on the serial screw, the feeling stops which suggests it’s as you say. take the finger off and it’s back again.
    is there any problem with this? eg will it lessen the life of the alix, danger of a static shock etc?

    No issue actually.  It’s not static electricity build-up (that will discharge once rather than be a continuous flow).  If anything, you can try to RMA the mains wiring in your house rather than the Alix ;D ;D
    Not everyone will encounter this issue because it’s got to do with the way the mains electrical wiring are run in a premise.

    If you have a grounded network switch (usually the rackmounted units that use an IEC with 3 prongs), you can use a Shielded-Twisted-Pair cable to connect the Alix to the switch.  That will effectively ground the Alix to mains earth through the shield of the cable.  ;D



  • Same here with my Alix. 🙂



  • the shielded cable (as suggested) did cure this issue and will work as long as the device you are plugging into is or can be earthed.



  • I’ve experienced this issue too. There is nothing wrong with the hardware, it’s just earthing/ground -which you can solve by using a little piece of wire from the board to the case



  • same experience with mine due to floating ground.
    I first experienced it with an old sony c1 laptop.  ;D and then with my shuttle pc with the brushed aluminium when I had no “absolute” grounding in my previous appartment.



  • @fastcon68:

    You got to be picking up stray voltage in the case, that would explain the strange feeling.  Make sure the components in the case are grounded well.
    RC

    Check that your AC power connection is grounded and wired correctly - Live, neutral, ground all need to be there!  You can get AC outlet checkers for a few bucks - failing that, see if the symptoms change if you power it from a different AC wall outlet.  If there’s a problem on the unit itself then it will be in the AC power adapter, not the motherboard.


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