[iceman143]

A number of Panasonic 42" plasma owners have been having difficulties with a buzz sound coming from the rear of the plasma. The sound is similar to that of a florescent shop light. Mine does not have that problem but I upgraded my power cord from the oem one. Is it plausible that a change in the power supply or power cord could reduce this effect?

 

[Steve Bruzonsky]

I once had a Toshiba 35" tv with a buzz, and they replaced the tv, still a buzz, and a repairman who knew his stuff came, a bit of foam or something by some transformer, and no buzz!!!! More likely cheap build quality permitting excess vibration. It shouldn't buzz/vibrate with regular AC. Fact that others report this suggests problem is how its constructed, not the AC.

 

[Alan Maher]

Iceman,


You can lower the buzzing noise but probably not eliminate it. Any number of parallel filtering techniques in series will lower the noise.


I think your 100% on the mark. I have always stated everything begins at the wall. I would suggest the following:


1. Purchase a high quality ac outlet with the isolated ground option.


2. You might want to consider wiring techniques for the main ac wiring to lower the noise floor. I have a few that I use in commercial applications that work very well. These are designed to be used with switching power supplies.


3. Some type of parallel filter designed for switching power supplies and digital frequencies.


4. Balance power should be an option.


5. Use a high quality large gauge power cord. The WireWorld Silver Electra III+ has one of the lowest noise floors I have ever heard.

 

[Alan Maher]

Steve,


The Panasonc PWD4 had a poor main power supply design. Panasonic stopped production twice to correct the problem.

 

[Steve Bruzonsky]

Alan, thanks. See, its as I suspected. With all the money you spend for a plasma tv, you shouldn't have to put up with a buzz. Assuming its still under warranty, contact Panasonic and demand that they either send out a serviceman to fix the buzz or that they replace your Plasma tv. Tell them you know that they've stopped production twice and apparently have a physical fix for the problem.

(Then, if you want to use "cleaner" AC for a better picture, fine, but you shouldn't have to do this to get rid of the buzz!!!!!)

 

[Alan Maher]

I agree with you, that is why I passed on the Panasonic and bought the NEC 42MP3. I could be standing 6" away and not here any type of noise coming from the plasma display. I haven't had one problem with mine yet (knock on wood). The scaler is excellent (no outboard required), the contrast ratio is on par with the Panasonic PWD4, and it offers the best colors compared to all the rest (reds are a true red vs bright red/orange). In my case it was money well spent.

 

[ciper]

I dont own this tv, and I hadnt followed the thread BUT I MAY HAVE A FIX. Way back when I was poor I wasnt able to buy the better electronic components. This meant most of the transformers I used were very cheap.


Any transformer will buzz depending on the load, just the better designed ones wont be as loud. You can change the resonant frequancy VERY easy just be changing the amount of mass in the transfomer. For large transformers like the ones that you would use in a mobile home (large) i would just stick a chunk of iron on the top.


I would say that one of you guys try this. Most transformers have enough metal that a magnet will stick pretty good. Not knowing how big the transformer is and what the space around it a magnet would be a very non permanent solution to try.


let me know, im curious.

 

[Alan Maher]

Maybe Ice will try, but I'm not opening up my $8k tv


The power supply inside uses the small transformers that you sometimes see inside digital audio components (not amp size transformers). I know the magnet trick well...but there is no room inside a 3 1/2" thick plasma to add anything extra. The main problem was panasonic used a low grade transformer inside an $8k tv. After people complained they upgraded the transformer and left the clients who bought a unit prior drifting in the wind. Power line harmonics appear to be the major problem. I have suggested in the past some type of power line filter. I would highly recommend something like a Kleen Line conditioner/regulator which eliminates all harmonic distortion on the power line.

www.elect-spec.com


Audio grade power products are just not up to snuff with this type of problem. They need some type of true isolation to prevent the problem. Isolation transformers just don't do it...they need some type of power regulation. A variac comes to mind. Filtering will also play a role. Look for something designed for switching power supplies (filter bandwidth: 10KHz to 30MHz or 250MHz pending filter company).

www.cor.com

 

[kevin gilmore]

Thanks Alan for the elect-spec link. I knew someone out there was selling motor driven variacs. A motor driven variac combined with a filtered fully isolated balanced power transformer makes for unlimited (not including $$$) pure clean power. The way to go. Definitely.

 

[iceman143]

Well I'm not real keen on opening up the back panel since my Panasonic doesn't have the buzz problem others have experienced. I did upgrade my power cord from the start which could have made the difference as Alan suggested. I like to tinker with things that I can't break but I feel confident in my ability to damage my plasma by poking around inside.


ciper, I wish I was a little more experienced or more adept because I would like to try your suggestion with the oem cord in place.