electrical - isolate TV from sound kit?

[dave]

Lad has home studio setting and all inputs go via one mixer. He plugs the TV STB sound output into it too. Problem is there is an almight (static-like) click when he does. Touching the screen of the STB output coax to a real earth on the mixers often gets a nice blue spark!

This has damaged stuff before (a usb channel for one). afaic see the output from the STB must be floating as there is no earth to it. There is obviously a safety issue here too (an rcd **is** used for all this setup).

Just to ask then, if there is some kind of isolator available to isolate the STB sound output signal from other electronic kit. thanks.

[John]

Does his TV Aerial have a booster amplifier?

I had an issue with a TV USB player - when connecting it I got a spark and could feel a tingle at times. I have connected the outer of the co-ax to the earthed chassis of my PC and all is well.

[Dave Plowman (News)]

IMHO it's likely due to the aerial connection if it's off some form of distribution amp.

But the classic way is to introduce an isolation transformer in the audio connection between source and destination. Something like this:-

[dave]

tvm

[NT]

I doubt its a safety issue. Earthing the STB would do it, or better leaving it permanently connected to the mixer. If he needs to unplug the signal lead, use a wire under case screws from one to the other.

NT

[The Natural Philosopher]

This is fairly standard on '2 wire' kit - the mains and neutral go to chassis via capacitors for RF interference suppression. That leaves teh chassis floating at a high impedance 110v..

If its a fices installation, earth the box.

If not, use audio transfornmer.

[Dave Plowman (News)]

Will likely cause a ground loop.