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In Reply to: RE: Isolate the TV AC power from the other stuff, so IMO yes a Triplite might work. posted by jhrlrd on July 12, 2016 at 10:56:05
Yes, it still makes the buzzing noise from the chassis/screen with the other gear turned off.
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Update: yes it's a Samsung. The noise is coming from the screen, which is drowned out by the audio. The issue is the same noise is being amplified through the speakers. Having reviewed the link Duster provided, I adjusted the picture settings, finding that the only adjustment that changed anything was the "eco" settings. "high" eco, which dims the screen did change the pitch of the noise to something a little more tolerable.
In the eco settings, there is an option for "screen off", but leaves the TV itself on. This setting eliminates the noise completely.
So that would indicate its not a grounding issue, no?
Just the screen generating noise and getting back on the line.
Forgot to mention, there is a vertical line on the screen which means the screen is indeed pooched. its hardly noticeable while playing a movie.
But I think I'll be on the lookout for a new TV rather than an isolation device.
Yup, they get noisy. There was a bulletin about it but they of course did not offer any refund or partial.
Turning the picture controls down doesn't help because you got those +200 and -200 volts switching all the time, and the pixel is switched on by about a 50 volt grid, or exciter. (do not take these voltage levels to the bank, and in fact they are specified for each unit separately due to differences in each tube manufactured)The pixwl is then turned off at a specifies time by the sustain boards.
All the voltage is still there even if the picture is all black.
Now if getting amplified through the stereo is a new phenomenon I would suspect grounds or filter caps. If you haven't had it hooked up to an amp before and now are just noticing this, it might just be a bad design.
This sounds like one of those tough dogs to fix. To get the hum out of the output audio can be a real PITA. As a Man who can wire a whole house ad has had high end electricians in the family I am not telling you to do this, but cutting the ground pin off the AC cord might help. Don't vut it right away just try one of those adapter thing we all have had to use, and do not connect the ground. This is a test, this eliminates ground current as the fault. If floating the ground works, that means to address the wiring in your house.
Other than that, the very most likely fault is bad grounds or filters in the TV. Actually, if are lucky you might only have to tighten some screws on the circuit boars in the TV, but that is extremely rare. Te thing would have to have been subjected to stress/vibration for that.
As I mention in my original post, the first thing I tried was a cheater plug. Didn't help at all. haven't tried ferrites yet. I moved the power cord in and out of proximity of other cords and didn't get a change, but the power cord is tucked away from the audio cords anyway.
Some plasma TVs make noise. It comes from the screen and there's nothing you can do about it. Some manufacturers put out a bulletin about it, Samsung among them I believe. Unless yours is a Hitachi or
Pioneer, it was very likely made by Samsung. Slight chance of it being an LG, but Samsung I think was the one that did most of the rebranding. For example a Zenith is a Samsung IIRC.
Realise what is going on in there. There are many electrical arcs in the screen. They are all of full power, voltage and current. The duration of the arc sets the brightness of each pixel. All these elements are getting switched between plus a couple hundred volts and minus a couple hundred volts. The X and Z sustain boards supply this and are a common failure because they run like an amp that constantly turned up into hard clipping. The transients are terrible and the whole thing is an EMI/FRI nightmare. That's why they have metal backs. They don't use metal unless it is absolutely necessary. If they had a cheap enough conductive plastic there would be no copper on the circuit boards.
If the noise it coming from the screen and it just started a screen failure might be in your near future. If it has always done that don't worry. If you actually CAN tell for sure the noise is coming from the back, that would be rare. Al of them use SMPS technology, there are no transformers running at 60 Hz. In some rare cases a standby transformer, but that would be quite rare. You would have to have some kind of strange model made on Mars or something.
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