An audible hum - not strictly Naim - help needed

Posted by: MichaelC on 04 November 2003

Can anyone help?

My TV, a Loewe Aconda, has developed an audible hum from both speakers. This hum is audible even with the sound on the tv switched off. The tv has only just been returned from repair (second time in as many months) for this problem and still it persists. The tv is linked via a Rotel receiver, which in turn takes feeds from Sky+, Rotel DVD player and a Loewe vcr.

On the assumption that when the tv is hooked up on the repairers test bench there is no apparent problem could it be that the tv is picking up interference from mains cables, the mains etc?

Having said that the problem of the audible hum has only manifested in the past couple of months so perhaps this is unlikely.

Everything is plugged independently into wall sockets on a ring main that only serves the above equipment plus my hifi.

Or is this the case that the tv has to go in for repairs again - oh what aggravation.

Thanks

Mike
Posted on: 04 November 2003 by Frank Abela
Mike,

Unplug all the sources and the aerial from the TV. If the hum is still present, then it I think it's likely there's a problem with the unit.

If the hum is not present when the sources are unplugged, then start adding the aerial and subsequently the sources until the hum comes back. If this happens you probably have an earth loop. You could try to use a 4-way block to earth all the bits to one point in this case.

Regards,
Frank.
All opinions are my own and do not reflect the opinion of any organisations I work for, except where this is stated explicitly.
Posted on: 04 November 2003 by MichaelC
quote:
Originally posted by Frank Abela:
If the hum is not present when the sources are unplugged, then start adding the aerial and subsequently the sources until the hum comes back. If this happens you probably have an earth loop. You could try to use a 4-way block to earth all the bits to one point in this case.


Frank

Thanks for that - I will give it a try.

Regards

Mike
Posted on: 06 November 2003 by MichaelC
Update

I followed Frank's suggestion - which involved a significant amount of furniture and debris moving to access all sockets, cables etc. Having disconnected all units from the wall sockets and all interconnects to the tv I found a faint (call it a background hum emanating from the tv set). Oddly enough I then hooked up the Rotel receiver and found that as soon as I connected the coaxial cable the hum ramped right up in terms of volume/obtrusiveness.

Looks like I will try a different coaxial cable but ultimately I guess the tv will have to go back to the repairers again Frown

Regards

Mike