Home entertainment system grounding / static discharge issue

[tobia]

Hi all

I have a small home entertainment system comprised of the following:

• a fanless mini-computer with Linux, my main source of A/V data these days
• a STB dish decoder
• a blu-ray player
• a hi-fi amplifier, where all audio ends up unless I'm using headphones
• a DLP projector, where all video ends up
• a number of connections between those, mainly HDMI and analog audio cables
• various USB attachments to the mini-pc, including an El Cheapo USB-powered HDMI switch
  

Most pieces of equipment are correctly grounded to earth, but some of them only have a groundless plug. The mini-pc in particular is powered by an isolated PSU through a +/- barrel connector, so its ground, including the ground of the stupid HDMI switch, is clearly floating.

The problem is, whenever I'm sitting on my couch (synthetic fabric) and I reach for some piece of equipment, or whenever I'm wearing headphones that are connected to the PC output, I get static discharge (small shock) from my fingers to whatever chassis I'm touching, or from my ears to the metal case of the headphones.

The shocks are the small ones you would expect from common static discharge, the problem is that they send a shockwave throughout the entire system and make the DLP projector lose sync on the HDMI cable for a couple seconds!

I've been wondering how best to solve this issue, but I'm not sure. I would like to avoid having to wear a ESD bracelet while I'm watching the movies!

Can I solve this issue by somehow connecting all the floating grounds (HDMI, USB...) to earth through a 1MΩ resistor (or better yet, one of those yellow ESD plugs)?

Am I missing something really stupid about this?

[Digorion]

Hello!
May be antistatic spray for your couch could solve your problem? I think it costs about 3-5$.

[Zero999]

Are you sure it's static? The fact that this only occurs with unearthed appliances, indicates it's more likely to be leakage across the Y-capacitors, in the switched mode power supplies. You probably need to connect the chasses hard down to earth, to get rid of the shock.

[lucatz]

Unplug one component at a time and see which one causes issue.

[S. Petrukhin]

Are you sure it's static? The fact that this only occurs with unearthed appliances, indicates it's more likely to be leakage across the Y-capacitors, in the switched mode power supplies. You probably need to connect the chasses hard down to earth, to get rid of the shock.

Apparently, we need to find out which wire the Y-capacitor is connected to and install this plug wire in the socket N of the outlet. 
I think the fanless PC has no a chasses...

[Zero999]

Are you sure it's static? The fact that this only occurs with unearthed appliances, indicates it's more likely to be leakage across the Y-capacitors, in the switched mode power supplies. You probably need to connect the chasses hard down to earth, to get rid of the shock.

Apparently, we need to find out which wire the Y-capacitor is connected to and install this plug wire in the socket N of the outlet. 
I think the fanless PC has no a chasses...

Reversing the plug polarity won't help, because the Y-capacitor will be connected to the bridge rectifier.

[Digorion]

You can use an single-pole voltage tester (looks like a screwdriver https://www.haupa.com/es/productos/detalles/page/1729/product/100647/) or other types of voltage detectors to find out if the case is under high voltage.

[S. Petrukhin]

Are you sure it's static? The fact that this only occurs with unearthed appliances, indicates it's more likely to be leakage across the Y-capacitors, in the switched mode power supplies. You probably need to connect the chasses hard down to earth, to get rid of the shock.

Apparently, we need to find out which wire the Y-capacitor is connected to and install this plug wire in the socket N of the outlet. 
I think the fanless PC has no a chasses...

Reversing the plug polarity won't help, because the Y-capacitor will be connected to the bridge rectifier.

Yes, I wrote something stupid. Sorry...