Weird Buzzing From TV Backlight Tubes

[paul_g_787]

Hey guys. I was playing online this evening and was wondering about something that I have never found an explanation for before.

My TV, a Sony KDL-40W5500 from 2009, sometimes randomly starts buzzing. The buzzing sounds like 50Hz mains buzzing but I it appears to be from the backlight fluorescent tube driver and if I turn off the backlight in the settings then back on it goes away. But comes back another time.

The weird thing is the buzzing happens only occasionally, sometimes happening in small more frequent occurences and then not happening for ages and ages.

The buzzing starts quiet then over a few minutes gets very loud and eventually stops suddenly

It has done this on this TV since it was brand new and also our old KDL-37W5500 had the same issue before we upgraded it to a larger one.

Now the TV is working fine but I am just wondering what on earth the buzzing could be as I have never encountered it on another TV before or since.

Just something that I find interesting and would like to understand why.

Can anyone suggest any reason for this?

[moffy]

Sounds wierd. I have a similar problem with some ceiling fans but I am pretty sure it is due to the switching tones that the electricity supplier puts on the lines to turn controlled loads on or off. They only appear at certain times of the day, but can continue for a few minutes before disappearing.

[paul_g_787]

Sounds wierd. I have a similar problem with some ceiling fans but I am pretty sure it is due to the switching tones that the electricity supplier puts on the lines to turn controlled loads on or off. They only appear at certain times of the day, but can continue for a few minutes before disappearing.

That is interesting! I never even knew such a thing existed! Very clever.

Now you mention it, it does appear to occur at the same time of day on select days of the week.