Buzz off!

[chazza]

My TV in my bedroom is connected to the main aerial that the other TVs in the house are connected to.  For some reason the Channel 4 in my room buzzes loudly about half the time. It doesnt happen to any of the other TVs in the house. The buzzing gets louder when the volume is increased and vice versa. 

The only way we can find of stopping this is to hit the tuning buttons (in the front of the TV) up or down a few times to knock C4 slightly off the station that it is tuned to.  However there is no way of storing this new setting, and everytime you change channels and then go back to C4, the buzzing starts up again.  It often gets louder if there are words on screen eg subtitles (not teletext ones) or when someone is being interviewed and their name is shown.

Has anyone any idea how to stop this or what is causing it?

[smorodina]

It sounds like it is the tuning. Perhaps the Automatic frequency control (AFC or AFT) is not switched on. There may be a switch for this somewhere. Occasionally, the AFC itself plays up and turning it off is a solution! What model is it and how old?

[Tim Baxter]

I would ask the same question and give the same answer but, additionally, older TV sets used to suffer from 'sound on vision' which meant that when the picture got too bright or too much contrast (like text subtitles on the screen) the TV started to distort the sound, humming etc.  It too was usually caused by poor tuning so turning off the afc might cure it.  Modern TV's have inbuilt selection of channel frequencies, it might just be that you are recieving signals from another transmitter which is using an adjacent frequency and your afc is fighting between the two and can't decide which it should be 'locking on to'.

[Bob A Job]

If it only buzz's when certain colours are on the screen then its the contrast problem. it could also be interferance of some kind..

I.E. a transformer for a games consol or computer being too near the TV or ariel. try unplugging all other electrical appliances and see if it goes away

[chazza]

Its a JVC, not sure of the model, 14inch portable.  It is about 7 years old but in perfect condition as it is rarely used.

 

The only other electrical appliance near it is the video.  I cant understand why it only ever happens on one channel though?