[mythtv-users] audio issue - HDMI tv

Simon Hobson linux at thehobsons.co.uk
Fri Mar 30 19:33:33 UTC 2018

Tim Draper <veehexx at zoho.com> wrote:

> Touch the ground of HDMI cable to any metal part of the TV and the sound occurs so definitely ground induced.
> what options do i have to fix it? seems like internal TV issue and not fussed enough to resolve the issue to go buy a new one. Can i simply run a wire from a ground point down to the mains socket earth pin (3pin UK; green/yellow)?
> mains connection is 2way wall socket > with 1 of the sockets to a 6way extension. all the kit connects to the 6way; tv, amp, rpi, laptop etc.
> could a faulty mains socket cause this, or is it device issue?

Is the noise a low frequency (50Hz) hum ? Which devices have 2 pin (or core) mains and which have 3 pin (or core) ?

Lots of kit only has a 2 wire mains connection - and hence no earth connection. The input filters typically are two capacitors connected L-chassis and N-chassis, which with an unearthed chassis means a potential divider pulling the chassis to half the mains voltage !
Thus it's easy to end up with units earthed through the connecting leads, with obvious problems.

Connecting the chassis of each unit to the same earth as they are plugged into should deal with that - and it's a cheap thing to test.

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