Mains hum, help needed

[andymac]

Hi all,

Since installing my new TV, my system has developed a mains hum.
The only thing I can think of that may be causing this is that the new tv has a fully wired "kettle lead" for the mains feed, whereas my old one has a 2-core (no earth) lead.

Just wondered if anyone had any suggestions?

System info in case its relevant:
Panasonic GT60 plasma
Pioneer LX-51 receiver
SKY HD Box
BD/DVD player

Everything routed to the display via my receiver using hdmi.

Thanks in advance,

Andy.

 

[nopiano]

Not familiar with your kit, but the problem isnt unknown. Have you tried swapping the sockets you use, or trying a different extension? You may get lucky by trial and error, which is worth the effort before trying another cable.

What does your supplying dealer say about it?

 

[andymac]

I've not been in touch with the dealer who sold me the tv as yet, only had it a couple of days and thought I'd see if I could solve it myself (or with the help of people on forums).

I've just tried swapping the lead and the socket Im using, it didn't help

I'm going to try disconnecting every piece of kit one unit at a time, see if I can trace the hum.

 

[audiodarkness]

Hi Andy,

I wouldnt be surprised if the TV (or another bit of kit) is dropping noise onto your mains ring. It could also be some level of DC offset on the mains ring. I'd give isol-8 a ring if I were you, they really know what they are talking about when it comes to this stuff.

 

[nopiano]

Hi Andy,

I wouldnt be surprised if the TV (or another bit of kit) is dropping noise onto your mains ring. It could also be some level of DC offset on the mains ring. I'd give isol-8 a ring if I were you, they really know what they are talking about when it comes to this stuff.

I wouldn't have thought that 'noise' in this context would result in hum, which for me is an earth loop or similar. We may be saying the same thing, but I think there is probably a difference here.

@ Andy, certainly, the item by item approach is worth trying. When I was testing my system (hifi and TV in same room) a few years ago, the noise I detected with a 'sniffer' (not hum!) was actually mostly coming from my amp, but my Sony TV actually eliminated some of it when in circuit, presumably because it had some decent in-built filtering. The hum presumably isn't being picked up in interconnects, is it? Do you have any coiled up leads?

 

[andymac]

Andy, certainly, the item by item approach is worth trying. When I was testing my system (hifi and TV in same room) a few years ago, the noise I detected with a 'sniffer' (not hum!) was actually mostly coming from my amp, but my Sony TV actually eliminated some of it when in circuit, presumably because it had some decent in-built filtering. The hum presumably isn't being picked up in interconnects, is it? Do you have any coiled up leads?

I went through every piece of kit again, this time disconnecting not only mains leads, but interconnects too.

Although the hum went away with the TV unplugged, turns out it was a phono interconnect from my DAB tuner causing the problem.

Phono leads replaced with optical, problem solved.
Thanks for your help all

 

[dsuciato]

Ground the blu ray player & the hum gone.