!!! FOUND !!! Fix for BUZZ on Panasonic PLASMA 2010 - AVS Forum
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post #1 of 54 Old 04-07-2011, 01:43 AM - Thread Starter
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Just to inform you of my personnel devs.

I bought a P50V20M here (middle-east, I am expat) 2 weeks ago. Everything was fine (really a perfect picture), made light calibration, and enjoyed

After a few days, suddenly I got some buzz coming from the screen . Went off after 20mn.

Second day, happened the same thing .

Finally I spent 20h on internet to understand noise in smps, how to troubleshoot etc...

In between I found an extremely interesting document from Panasonic Australia (this is available on the web if you pay for it)(I paid). I copy the some part of the text (I imagine original protected by rights):

Quote:
Symptom :

Loud Buzzing Sound
Buzzing sound that varies with screen white levels

Cause :

The varnish coating on a small quantity (<0.4%) of T201 transformers (located on P Board) has leaked into T201 bobbin shaft. When TV reaches normal operating temperature, the varnish coating expands, causing a hairline fracture in T201 ferrite core. Core fractures causes either a very loud constant buzz sound evident at normal volume levels (vol=20) or variable buzzing sound dependant on screen white levels.

It TV set is more than 20 hours old without this symptiom, then T201 is OK.

T201 factory improvements were introduced as follows :
TH-P50V20A Q*032**** onwards
TH-P54V20A Y*035**** onwards
TH-P50VT20A Y*041**** onwards

Cure : Change T201 on P Board
I then dismantled the TV, made a lot of pictures of everything, overall and macros, and start analysing.

Outcome :
- Noise is coming at 90-95% from T201 tranformer
- By pressing windings, I removed a bit of noise
- By compressing the transformer from left to right (TV standing normal position), I could remove 90-95% of the noise

Then I closed the TV, knowing more or less what to do.

This morning when I looked at pictures, imagine what was my surprise when I found the "CRACK" they are talking about in the document.

I will put the link later on (just starting to post, not allowed yet).

Solutions :
- Replace P Board
- Replace transformer (but how to make sure it is not again a badly manufactured one ?)
- Fabricate a frame to hold the transformer (I will try this tomorrow).

My understanding :
- It is much more than 0.4% of TVs !!!!
- Problem is not so easy to reproduce : need to get to final operating temperature with a big power demand (whites)
- Even it is not there during 50h, it does not mean that it will not break later on (mine was working 2 weeks in a shop with very strong A/C like 19-20°C); I guess problem came later on as in my home it is roughly 24-25°C at this time (and the transformer is rather hot).

You can find all my posts in French in homecinema-fr (look for neopdp V20 nash35nash).

Hope it helps you !
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post #2 of 54 Old 04-07-2011, 07:07 AM
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Quote:
Originally Posted by dominique.wille View Post
You can find all my posts in French in homecinema-fr (look for neopdp V20 nash35nash).
Thank you for the information.

The link appears to be here.


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post #3 of 54 Old 04-07-2011, 04:35 PM - Thread Starter
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Picture of the crack (macro) on my t201 transformer.

Barely visible with eyes only (difficult).


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post #4 of 54 Old 04-07-2011, 04:36 PM - Thread Starter
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And the third...
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post #5 of 54 Old 04-07-2011, 04:36 PM - Thread Starter
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GOOD NEWS

At the end of afternoon, with my experience :
- Panasonic australia note
- Picture of my T201 transformer with crack visible
- Hand tightening that cancels 90% of the buzz

I opened the plasma once again...

Made a very high technological fix....

And then, guess what... no noise at all for 6h continous operations....

Just a small whistle from two side coils. To listen at it, hear at less than 20cm on the back, volume zero level & no noise in room.

Please note :
- Easy screen opening. just take care which bolts goes where (4 types)
- Remove power cord when screen in stand-by (to empty capacitors)
- No metal inside, do not touch anything

Necessary tools (I added another one. The big blue can not be used inside)


Prepare tightening frame


Positionning the frame


Typical tightening of one link : rotate the tool, taken support from the big part of the next one.


After rotation of one. Do the same all around several time until very tightened. Then cut the 4 ends


After final tightening


Look at ration "transport risk, loosing warranty, etc..." and also "how to make sure that the new transformer is not as well a defective part ?"

Anyhow it works 100% at my home. Just a question mark on the long term of plastic. If it fails I will make a solid steel frame with pressure bolts.

See you !
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post #6 of 54 Old 04-08-2011, 01:28 AM
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A very interesting thread and a novel fix. Probably a bit of a stretch for most folks who might not be as technically inclined as you, but still....... a well documented and highly understandable explanation for fixing what has been quite a problem for some folks. Nicely done .

I hope you will check back in occasionally and let us know if this fix seems to help over the long-haul. Good luck and happy viewing.
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post #7 of 54 Old 04-08-2011, 01:30 AM - Thread Starter
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Thanks.

Now 12h operating continuous and still no noise at all.

Before it was coming after 20mn to 1h, more or less.
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post #8 of 54 Old 04-08-2011, 01:53 AM
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Wow, this is actually a very interesting find... I wonder if all plasma brands could be fixed by replacing this part with a non cracked piece?

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post #9 of 54 Old 04-08-2011, 02:39 AM - Thread Starter
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No it will only work as much for panasonic broken transformers. Maybe they supply some other companies... Open & see !

But generally the max. noise is :
1 - The smps transformer
2 - The coils around
3 - Anything that can vibrate
Caps not secured
Bolts not tighten
Heatsink not well tighten
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post #10 of 54 Old 04-08-2011, 03:17 AM
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wow

This thread should be turned into Sticky Thread!

anyways...

So far, my 50 inch Viera G20 that was built in March 2010 has no issues. No buzzing etc.

I wonder if connecting my 50 inch Viera G20 to an $50 APC Line R 1200 watts Voltage Regulator does help keep my Plasma TV reliable... My Viera G20 is connected to that voltage regulator since the day I first turned on that TV
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post #11 of 54 Old 04-08-2011, 03:49 AM - Thread Starter
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Quote:
Originally Posted by 34HFX83 View Post
wow

This thread should be turned into Sticky Thread!

anyways...

So far, my 50 inch Viera G20 that was built in March 2010 has no issues. No buzzing etc.

I wonder if connecting my 50 inch Viera G20 to an $50 APC Line R 1200 watts Voltage Regulator does help keep my Plasma TV reliable... My Viera G20 is connected to that voltage regulator since the day I first turned on that TV
It has an impact only if you have an "in-line" UPS meaning that the current is permanently generated by the UPS (no direct connection to main power network).

I have exactly this setup : whatever is at the entry, I have 220v +/-0.1V and 50.0Hz +/-0.1Hz ("Pulsar UPS"). Still had the problem because of manufacturing defect in the transformer.

But for others it makes sense to filter the main power supply. This transformer in SMPS is almost directly connected to main power. If it is full of harmonics & defects then for sure you decrease the life & you increase the noise.
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post #12 of 54 Old 04-08-2011, 07:00 AM
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Panasonic apparently also has given out service hints about the buzzing, available only to technicians with accounts at ServiceBench. I wonder if those hints are like the one OP dominique.wille purchased?


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post #13 of 54 Old 04-08-2011, 08:14 AM
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Very good post.. Thankyou!!
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post #14 of 54 Old 04-12-2011, 01:18 AM - Thread Starter
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Just a few updates :

- Still no noise at all (fix made approx. 60-80h operating time ago)

- I put the Panasonic note on-line (no rights or property disclaimer on it)



- Picture of the crack on my transformer (macro)


nash
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post #15 of 54 Old 04-13-2011, 02:39 AM
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Quote:
Originally Posted by 34HFX83 View Post
wow

This thread should be turned into Sticky Thread!
Agreed...especially if this becomes "the" fix for a number of Panasonic TV's.

Anyone else looked into this?

I have a 50GT25 with a buzz when screen is displaying a lot of white content. Can be heard over "normal" volume 10 feet away if my head is in the right place and especially if I turn my head to the side. Probably can live with it just have to move head a bit.

One day would like to open the set up and put the cable ties around the transformer.

Is it more fun to use the equipment or talk about it on AVS?
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post #16 of 54 Old 04-13-2011, 02:51 AM
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Quote:
Originally Posted by dominique.wille View Post
GOOD NEWS

Anyhow it works 100% at my home. Just a question mark on the long term of plastic. If it fails I will make a solid steel frame with pressure bolts.

See you !
Don't know but if the frame of the transformer gets hot it could loosen the plastic frame; the cable ties could melt or stretch.

Does the transformer frame get hot?

Is it more fun to use the equipment or talk about it on AVS?
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post #17 of 54 Old 04-13-2011, 07:16 AM - Thread Starter
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It is around 40-50°C in stabilized operations.
It will not melt for sure; it could extend maybe.

I am waiting to see after 200h. Up to now it is ok.

If I have some changes I will update the forum.
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post #18 of 54 Old 04-13-2011, 01:10 PM
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Posting in here for reference, thanks.
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post #19 of 54 Old 04-13-2011, 07:17 PM
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Quote:
Originally Posted by 34HFX83 View Post

wow
This thread should be turned into Sticky Thread!

I agree. Impressive detective work. Excellently documented

Alex
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post #20 of 54 Old 04-14-2011, 06:58 AM
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Definitely should be a sticky.

Nice work, OP.
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post #21 of 54 Old 04-14-2011, 08:14 AM
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Here's another good thread where a guy found a buzzing coil on one of the boards:

http://www.avsforum.com/avs-vb/showp...8&postcount=75

http://www.avsforum.com/avs-vb/showthread.php?t=1249688


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post #22 of 54 Old 05-04-2011, 02:00 AM - Thread Starter
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Just a small update : still no noise at all !
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post #23 of 54 Old 05-09-2011, 10:39 PM
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Quote:
Originally Posted by dominique.wille View Post

Just a small update : still no noise at all !

Good to hear...

I finally opened mine up and that transformer T201 does seem to be where the buzz is coming from (mine is heard when lots of white on screen, sitting in front at center of screen...exactly where T201 is located).

I did not see a crack, the right side could not view due to the metal heatsink. Playing a bit with the transformer/frame I was able to reduce the buzz so I will try the plastic frame (have no cable ties yet).

I noticed the frame does get hot, but good to hear yours is still working.

Any ideas what the variable resistor (looks like VR251, marked Vsus) just above T201 does? Maybe something to do with the voltage?

Is it more fun to use the equipment or talk about it on AVS?
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post #24 of 54 Old 05-09-2011, 11:46 PM
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Quote:
Originally Posted by montanaman View Post

Any ideas what the variable resistor (looks like VR251, marked Vsus) just above T201 does? Maybe something to do with the voltage?

Did some looking (Google). Adjusts Vsus voltage which is sent to the SCAN and SUSTAIN boards. (Don't want to change that unless it is off.)

Will plan on the plastic frame.

Is it more fun to use the equipment or talk about it on AVS?
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post #25 of 54 Old 05-10-2011, 03:28 AM - Thread Starter
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Hi !

I would suggest NOT to touch the resistor since you risk the need to calibrate everything (and we do not have the manual).

For the crack, I did not see it myself with eyes (even inspection is my specialty in real life) because it is far too small. I saw it later on, when I looked at the macro pictures I have done with a picture camera.

If it changed the noise, I would say you have 95% to solve your issue quickly...

Just remember the rules :
- Disconnect the TV when ON, so it will empty most of capacitors
- When tightening (it must really very well tighten), take care not to make any effort on the transformer itself (or nearby components). I suggest to try to do it on something else before to find the best tool & way of doing it.

It is not obvious on pictures, but the best is to tight the link "n+1" by taking support on link "n". I made it like this with a rotation effect.
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post #26 of 54 Old 05-11-2011, 05:23 AM
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Another option would be to replace the transformer T201. I did not look at the board that closely; probably need to solder. Sometimes components are of the plug-in type and thus do not need soldering.

Replacing the entire power board would probably need a few voltage adjustments (there are two on the board). The Vsus and the Vda. The test points are also there, but I think you have to send the TV the proper pattern (probably 100% white) when setting the voltage. I do not have the service manual.

How hard to replace T201 (if you get get a new improved one)? Buy a power board off Ebay and just use the transformer. I used to work on the old CRT TV's for the military, but even with some experience, replacing components requires skill and a steady hand.

Still planning to try the plastic frame but it will have to wait until next week.

Is it more fun to use the equipment or talk about it on AVS?
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post #27 of 54 Old 05-18-2011, 12:04 PM
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Hi,
My TX-P42G20E buzzess on two boards inside. When facing the tv from behind the buzzing boards are located about on top right corner and middle left.
I suppose these boards don't have the kind of transformer people are talking in this thread?

Is the buzzing transformer located in the center of the tv, approximatel there where the power cord goes? Where is it located? I'm considering sending my Panasonic to get repaired because of excessive buzzing but I'm afraid that they will just say that the buzzing is normal and there cannot be nothing done.
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post #28 of 54 Old 05-25-2011, 10:11 AM
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Quote:
Originally Posted by Jeipii View Post
Hi,
My TX-P42G20E buzzess on two boards inside. When facing the tv from behind the buzzing boards are located about on top right corner and middle left.
I suppose these boards don't have the kind of transformer people are talking in this thread?

Is the buzzing transformer located in the center of the tv, approximatel there where the power cord goes? Where is it located? I'm considering sending my Panasonic to get repaired because of excessive buzzing but I'm afraid that they will just say that the buzzing is normal and there cannot be nothing done.

Yes the buzzing tranformer is at the center of the TV, on the board just above where the power cord plugs in. Panasonic really should move this board down low, or maybe put it in the corner.

The buzz you hear from the corner board I think is the "normal" plasma buzz, and is not the buzz that causes problems when watching the TV (from the front). The problem is the tranformer located directly at the center of the screen.

Some GT30 owners are also having this buzzing problem, so I don't think the new improved transformer or power board is guaranteed to fix. I have not yet taken time to put the plastic frame on mine, but will report back.

In my estimation Panasonic should get on this; either move the board's location or just find out the variables which cause this transformer to buzz and fix it!! It should not be a big deal. Maybe just a better quality transformer, or some way to insulate the noise this transformer is causing.

It is annoying reading about this problem on this and other forum boards; the anguish it causes and the uncertainty of buyers who have heard about the problem. The Panasonic picture is beautiful IMO and this pesky "fly" buzzing around needs to be addressed.

Is it more fun to use the equipment or talk about it on AVS?
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post #29 of 54 Old 06-25-2011, 12:09 PM
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Unfreakingbelievable (complètement incroyable)!

Thank you so much for not only posting this fix, but the supporting Panasonic material about this problem.

Since I bought this TV (TC-P50G25) in April 2010 I've gone through 4 P-Boards and now, thanks to you, I don't need to hear an incredibly annoying high-pitched sound when watching TV!
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post #30 of 54 Old 09-08-2011, 05:53 PM
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OMG.

I SO glad I came back to check about my buzzing. I think this might be the directional buzzing that comes out the front of my 55G20. I almost know that if I took off my back and took a picture of the power board, I'd find that hairline. I have a dead center directional buzz out the front of my 55G20 that gets worse with white content. Thats in addition to other plasma buzz out the back. However, the other plasma buzz *should* be corrected as the new x/y boards Panasonic sent me last time had the coils gooped up pretty well. I finally just accepted it, that "plasma's buzz", having been told all plasma's buzz and I'm crazy. I wonder if Panasonic would replace my P-Board 1 more time, already had it replaced twice.

absolutely incredible incredible job dominique.wille. I can't thank you enough. If Panasonic gives me the shaft, I'll just attempt to fix it myself.

Does anyone know beyond a replacement power board, have any other fixes been implemented to fix other sources of buzzing. I noticed on replacement x/y boards in January that several coils had been gooped up, but beyond that.

Is your fix still working for you these many months after you implemented it?
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