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    Lifted ground hdmi sparks

    Plugged a HDMI cable from my Nano PC into my home cinema any everything seems alright but before I plugged the hdmi into the amp I was checking where the socket was and if the cable would reach with the amp still in standby, accidently tapped the cover and was awarded with lots of little sparks. Switched off the amp and connected fine without the sparks but it got me wondering if the sparks are caused by the pd difference between the Nano PC ground and the lifted ground of the home cinema. I've come across this thing before between lifted ground USB devices and my PC in the past as well.

    Can anyone shine any light on this ?

    5 Comments

    possibly static discharge

    Original Poster

    srp111

    possibly static discharge


    Only occured when the Home cinema was switched on at the wall so I don't think it's a build up.
    I think I've found some information on it.
    Turns out a class 2 device i.e. double insulated with no earth will have a high resistance leakage path from chasis back to mains which is around half the mains voltage i.e. 120V but extremely low current.

    Because my nano PC is earthed I'm shorting this 120V low current on the amp hdmi chasis to earth thru the hdmi lead I think ? oO

    Why does it matter?

    craigstephens

    Why does it matter?



    It doesn't. LoL.

    Original Poster

    craigstephens

    Why does it matter?


    It matters because even though the HDMI standard supports hotswapping plugging your PC GPU into a non grounded amp or even some TVs could blow or damage the HDMI port. It would explain why manufacturers suggest switching off at the wall on both devices before connecting.

    Knowing why you shouldn't do something and why it happens only in some circumstances is important. Hopefully it will help a few people figure out why their new 4K TV HDMI port is fried after plugging in their 4K bluray player.
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