Panasonic 50" VT20 arcing at edge of panel to frame

[infrag]

I purchased a Panasonic 50" vt20 tv in 2010.
Its been going great guns and its been used moderately over its life time.

2 nights ago my wife was watching netflix on it for 30 minutes before she called me over to listen to the TV making a 'funny noise'.
She said all of a sudden it made a loud static electricity noise/crackling noise.
When I listened there was an obvious crackling noise like when you take off a jumper and have static electricity zap everywhere. I tried to identify the source but it seems to be random anywhere on the edges of the screen.

I've opened up the tv and checked for obvious bad caps. I've also checked all the screws were tight enough for grounding (I'd thought that might be an issue) Unfortunately nothing obvious to fix. I've checked the solder joints on the power supply board and flowed through a few joints as they looked questionable. The problem hasnt been fixed

The other symptom I've noticed (although I guess I could have caused it after my powersupply disconnection and re-connection) is that when turning the TV off the screen goes dark and usually it would click off after a number of seconds. However now it seems to remain in a semi-powered state and only occasionally switches properly off?


The TV is still fully functional that I've noticed and no lines or artifacts on the screen. However these noises have definitely never been there before and it always used to turn off properly.

Anyone got any ideas? Googling for Plasma tv and static/crackling noise I've only found about 5 other references to this problem and no solutions

I thought since it sounded like arcing that it might show if I turned the lights off and made the room dark. Turns out I was right.
All along the edges of the screen glass there is arcing to the metal frame. There isnt one given spot and it seems random where the sparks appear.

Anyone got any ideas on the why and how to fix?

[ReeceyBurger123]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

Picture of arc ?

[flocko]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

What side are you saying has the arcing looking from the front of the screen left or right ?

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

It arcs all around the edges of the screen to the metal frame. There is no one specific side or point and no point that arcs more than another that I can tell. If I remove the frame at the top it doesnt arc there but continues to do so along the sides.

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

Trying to take a picture of the arc isnt much fun. I've tried but I havent had anything useful to show. If I get the arc to appear you cant see where its arcing from or to.

[vinceroger69]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

maybe take a picture of the area where the arc is then edit the picture with arrows in ms paint etc.

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

OK well this is an example of where I've seen the sparks. The Glass arcs to the metal along the edges of the glass.

Another way of explain is the metal frame that sits in front of the glass on the edges has arcs all the way along it. I've remove the top part of the metal from and it does not arc there then as it has nothing to arc to. However the arcing occurs more in the other areas then.

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

I've also taken a video that looks horrible but you can hear the arcing and see a few of them in the area from the photo above. The extra buzz you hear now and then is me pushing/squeezing the bezel so the metal pushes against the glass a bit in that area which seems to make it spark more.

https://drive.google.com/file/d/0B-d...ew?usp=sharing

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

For the sake of completeness when I first had the probelm I ended up pulling a lot of the metal buffer cables off and metal frames when I couldnt find what was causing the arcing. When I re-assembled the arcing was gone. I did not know what but it worked fine for a period of time. Now the arcing is back like I expected. (I left the back of the TV off as I knew I hadnt really fixed the problem

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

I've tried running extra earthing wires to parts of the frame but that hasnt helped either. At one point I could get an arc from my screwdriver to another section of the frame which I thought was wierd. After proper earthing this doesnt happen anymore and I figured it probably only happened as I had some screws out holding that part of the frame to the rest of the TV.

[budwich]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

it sounds like some panel ground is missing and thus not allowing the panel to "discharge" to normal ground (actually remain at ground). As a result, once enough energy has found its way on the panel, its discharges to the nearest / best ground that it can find which appears to be the frame.

check all your grounds with a meter... ie. measure resistance to a known ground point.

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

OK sounds fair. Out of interest do you or does anyone know how a plasma screen panel is normally grounded? Is there a specific tab or spot I can look at?

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

Checked all the grounding points I could find. Everything looks good

[budwich]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

you checked them with a meter right? Looking at a ground is like looking at a girl... she might look good but when it comes done to "it", she might not be any good... :-)

try plugging the set into a different outlet.

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

Yes with a meter. I even ran extra earth wires to points to test. I removed the whole front bezel and metal frame that goes in front of the glass. I then cleaned the glass and the contact pad on the metal frame. While the frame was off the TV ran fine with no arcing. If I put the frame back on again it ARCs to the frame. Not to a single point... The whole way around. If you look at the front of the TV in between the bezel and the glass you can see the sparks.... Yes the frame is earthed properly and I've checked it to the earth pin on the power lead.

Any other ideas?

Does anyone have a service manual for this TV? I've found the tech manual but that didn't help much...

[tw2005]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

would have to be one of the most unique faults I've read about.

Maybe it's time to think outside the box. Would it be possible to place dielectric tape either on the bezel or on the panel in such a way to insulate it but not be noticeable?

[tw2005]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

The other symptom I've noticed (although I guess I could have caused it after my powersupply disconnection and re-connection) is that when turning the TV off the screen goes dark and usually it would click off after a number of seconds. However now it seems to remain in a semi-powered state and only occasionally switches properly off?.

Can you explain this better? What is a semi-powered state?
Is this remote turn off? Is it master switch turn off?
Is the LED going from green to red?

Are you referring to the relay click you may hear?

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

Can you explain this better? What is a semi-powered state?
Is this remote turn off? Is it master switch turn off?
Is the LED going from green to red?

Are you referring to the relay click you may hear?

What I'm referring to may be just paying to much attention to the TV and it may have been normal. But what I meant was that when you turn the TV off with the remote it would turn of the display but not click the relay after the normal 30second delay to go into low powered standby mode. When i would hit the power button on the remote the tv would be syraight back on again with no or very little delay. Its possible I was just too impatient as I haven't noticed this symptom since. Sorry for the mis information.

[infrag]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

would have to be one of the most unique faults I've read about.

Maybe it's time to think outside the box. Would it be possible to place dielectric tape either on the bezel or on the panel in such a way to insulate it but not be noticeable?

That should be possible I suppose although if there is a build up of charge and no metal to zap to would it zap my ear when I'm listening for the spark?

[tw2005]

Re: Panasonic 50" VT20 arcing at edge of panel to frame

What I'm referring to may be just paying to much attention to the TV and it may have been normal. But what I meant was that when you turn the TV off with the remote it would turn of the display but not click the relay after the normal 30second delay to go into low powered standby mode. When i would hit the power button on the remote the tv would be syraight back on again with no or very little delay. Its possible I was just too impatient as I haven't noticed this symptom since. Sorry for the mis information.

yep, that's normal. It remains armed , if you hit the remote it'll fire up quicker with no relay latch as it is already latched but as you say if it does does get a command to turn on after that time you 'll here the relay de-energise.

Ever heard the relay latch and delatch at weird times through the night without touching anything?