Customer has a dimmer that quit working, wouldn't turn on the lights at all like the circuit was dead. Pulled the dimmer, there was power to it, found they installed all CFL's on an old dimmer. I installed a CFL friendly dimmer and all dimmable cfl's and it worked fine. As I was putting the plate back on I noticed the TV had a slight buzzing (it was off). I checked the connections on the dimmer (it fed the outlet the tv was on) and everything was tight. Was it the dimmer? I have installed a lot of these and never had anything like this before.
CFL theory for geeks:
http://www.eetimes.com/document.asp?doc_id=1272528
No modern TV is ever completely off unless it's actually unplugged. I encountered such buzzing a time or three during my electronics career (pre-CFL). It was usually due to crappy filtering on a relatively high-current device attached to the circuit.
Sometimes replacing that device cleared it up, sometimes moving it (or the radio/TV) to a different circuit worked, or using a line conditioner did the trick. Sometimes the client just opted to live with it.
Have you come across a tv that doesn't cut the power to the amp when in standby?
Yep, though not in the way you're thinking.
Semiconductor switching, especially years ago, isn't 100% leakproof (though for most practical purposes it can be considered to be). Also, capacitors can remain energized for quite a long time after source Vcc has been removed. If there isn't circuitry to clamp down the input signal line, random noise can still wind up getting processed even with the unit unplugged. :thumbsup:
All these TVs that turn on with remote controls are always on. The old days of an actual switch that kills the power (On/Off/Volume) are long gone. I don't believe I've ever seen a TV that used an electromechanical relay anywhere in the circuitry - as already pointed out there's no real benefit, they're big, expensive, and unreliable.
Turn on a big plasma and tell me where the loud click comes from.
I haven't worked on plasmas, but if I can find a diagram, I'll give you an anwser.
What I don't understand is how can a buzz noise come through a Tv when it's amplifier,...and some other main circuits are shut off.....