Green Blob back again for 2013! - AVS Forum
View Poll Results: What model ST60 do you own and does it have the green blob?
Yes, it has the green blob on my 50st60 3 25.00%
Yes, it has the green blob on my 55st60 0 0%
Yes, it has the green blob on my 60st60 0 0%
Yes, it has the green blob on my 65st60 0 0%
No, does not have the green blob on my 50st60 2 16.67%
No, does not have the green blob on my 55st60 5 41.67%
No, does not have the green blob on my 60st60 2 16.67%
No, does not have the green blob on my 65st60 0 0%
Voters: 12. You may not vote on this poll

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Old 05-09-2013, 10:37 PM - Thread Starter
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Yeah I know I'm new here, so my opinion isn't respected, but I don't care. I just want to share my story and hopefully get some feedback. I have never heard of the Green Blob before, till I got my first Panasonic Plasma. I ordered a 50ST60 about two weeks ago from ABT.com. I ran the break-in slides for about 40-50 hours. I bought the Calman 5 enthusiast and the X-rite display pro and calibrated it with near perfect results. I then noticed the green discoloration on both sides of my screen, taking up about 2/3s of the screen. I went ahead and did some research and was dumbfounded! Sure it is faint on most content, but can be seen on gray test patterns or in movies with bright scenes. I called ABT to exchange for another set, but they are currently out of stock. So I went ahead and exchanged it for the 55" instead. From what I have notice from my research on the Green Blob, most people that have it, has the 50" model. So I'm hoping to have better luck with the 55" instead. I also contacted Panasonic and got a case#, not sure they'll do anything about it, but I guess it doesn't hurt to try. I believe that Panasonic makes the best TV's out there and would have no competition if they can just stop shipping out defective panels!!! I would hate to have to buy any other brand.

I will report back when my 55" arrives.
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Old 05-09-2013, 11:12 PM
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I had a pink blob on my 50ST60, it was in the center of the picture taking up about 40% of the screen. I don't believe the units are defective, just don't have the VSUS calibrated correctly.
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Old 05-09-2013, 11:15 PM - Thread Starter
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Quote:
Originally Posted by Moonchilde View Post

I had a pink blob on my 50ST60, it was in the center of the picture taking up about 40% of the screen. I don't believe the units are defective, just don't have the VSUS calibrated correctly.

What is VSUS? I believe they are totally defective. Mine is calibrated in almost perfectly.
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Old 05-09-2013, 11:29 PM
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No, the VSUS is the voltage sustain on the power board. There is a potentiometer to calibrate it. If it's incorrectly calibrated, then the plasma gas isn't being driven properly so it will have tints. At least, this is what I gather from tom669's post about the issue of color blob tints.
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Old 05-09-2013, 11:37 PM - Thread Starter
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Quote:
Originally Posted by Moonchilde View Post

No, the VSUS is the voltage sustain on the power board. There is a potentiometer to calibrate it. If it's incorrectly calibrated, then the plasma gas isn't being driven properly so it will have tints. At least, this is what I gather from tom669's post about the issue of color blob tints.

Oh OK. So do all the Panasonics have this problem? Have you fixed or planning on fixing it?
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Old 05-10-2013, 12:18 AM
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I don't think all of them have the problem. It's probably a few that passed by the QC. I returned mine for various reasons. There is another member here who may fix his, hopefully he chimes in.
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Old 05-10-2013, 12:20 AM - Thread Starter
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Quote:
Originally Posted by Moonchilde View Post

I don't think all of them have the problem. It's probably a few that passed by the QC. I returned mine for various reasons. There is another member here who may fix his, hopefully he chimes in.

Thanks for you input. I appreciate it!
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Old 05-30-2013, 01:34 PM
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Erased..
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Old 05-30-2013, 01:40 PM
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I have the 60ST60, had it for a month or so, I do not have the issue. I use my TV as a PC monitor at times and when i have a white screen up (Full screen) I see no uneven color or unusual tints.


Edit: I do look for things like this from time to time. I will on occasion look for IR also because I noticed that I had IR from my Browser once and ran the WOW disk pixel flipper to remove it.
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Old 05-30-2013, 04:45 PM
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I've played around with tweaking an older Panasonic plasma. Interestingly, I am able to replicate complaints of "green/cyan blob" and "pink blob".

If VSUS is set too low and VAD is too low, the blob is typically cyan or green tinted. IR is also more prominent on darker images.
If VSUS is set too low and VAD is set right, the blob is typically pink tinted.

One easy way you can see if VSUS is low and if VAD is low or OK is checking for dead pixels. If VAD is low, then on a full white field you should be able to see the occasional dead pixel (at least one randomly every ~4 in^2 was what I noticed, over 50 very faint and impossible to see from viewing distance.) However, if VAD is OK, even if VSUS is poor, you should see almost no dead pixels.

VSUS on newer Panasonic PDP can be adjusted from service menu, but VAD adjust requires you to open the unit up.
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Old 06-01-2013, 07:02 PM
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tom - I've been discussing this with Moonchilde (obviously thanks to your original suggestions on this topic), but wanted to follow up with my current attempts on my 50 inch ST60 (I'm seeing pink blobbing in a couple areas of the screen). I'm using the following multimeter:

http://www.amazon.com/Equus-3320-Auto-Ranging-Digital-Multimeter/dp/B000EVYGZA/

I've got it set to DCV (the first position to the right of "off", which is what the main amazon picture shows), which seems like what I should be using, but the readings don't seem to fall into the range I was expecting, and they don't seem to stay consistent when I check every few minutes (which may be normal, I don't know). Moreover, when I tweak the pot (which appears as a white screw a couple of inches below the vsus cap), the reading doesn't change...

I'm doing readings on the wires coming out of the capacitor labeled vsus, and I'm getting readings around 1.2 (the screen says mV, which has me confused as that's not a lot of power, unless I'm reading it wrong, perhaps "mV" is indicating the greatest resolution of the reading; nevertheless if it's in volts, then 1.2 is nowhere near the 140-200v you've discussed we would expect).

As a side note, I already tried the service menu adjustment from low to high vsus, but that didn't do anything, so I left it on low. Also, to your previous post, I do not see any dead pixels on my screen, so I guess that would point towards a possible vsus issue only.

Pictures of the board and close up of the vsus area:



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Old 06-01-2013, 07:39 PM
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Quote:
Originally Posted by tom669 View Post

I've played around with tweaking an older Panasonic plasma. Interestingly, I am able to replicate complaints of "green/cyan blob" and "pink blob".

If VSUS is set too low and VAD is too low, the blob is typically cyan or green tinted. IR is also more prominent on darker images.
If VSUS is set too low and VAD is set right, the blob is typically pink tinted.

One easy way you can see if VSUS is low and if VAD is low or OK is checking for dead pixels. If VAD is low, then on a full white field you should be able to see the occasional dead pixel (at least one randomly every ~4 in^2 was what I noticed, over 50 very faint and impossible to see from viewing distance.) However, if VAD is OK, even if VSUS is poor, you should see almost no dead pixels.

VSUS on newer Panasonic PDP can be adjusted from service menu, but VAD adjust requires you to open the unit up.

What is the source of the non-uniform color? Are some sub-pixels getting more wall charge than others?
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Old 06-01-2013, 07:54 PM
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Quote:
Originally Posted by zoyd View Post

What is the source of the non-uniform color? Are some sub-pixels getting more wall charge than others?

My guess is related to the energy conversion from the discharge in the plasma cell to UV light. If the energy conversion is insufficient, I think it may be leading to an insufficient UV output. Increasing VSUS (breakdown voltage for plasma gas) puts more energy into the PDP, but it probably causes more of the energy to be in the lower UV band (lower energy), which leads to cyan tint. Decreasing VSUS reduces panel energy, reducing the higher band (higher energy) UV. That is from someone who specialises in electronic; physics isn't my specialisation.

And the reason blobs appear is because the panel gas is not totally even in all cells and the probability of an individual pixel successfully dischaging and emitting light is proportional to: energy added times gas concentration. Manufacturers try to set this at 99.999% or something high to avoid dead pixel problems. Uneven gas is not a problem if you make sure the cells have good phosphor coating, and each cell has the same amount because what determines the light output is the phosphors, not the amount of UV. The unconverted UV is simply wasted as invisible (harmless) light. Now, this may be one reason the red/pink/cyan blob pops up in recent models but tended to avoid older ones. As manufacturers try to improve panel efficiency they drop the energy going into the panel as much as possible, avoiding wasting too much as UV. If they go too far -- if you end up on the wrong end of the production bell-curve -- then you have the blob symptoms.
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Old 06-01-2013, 07:57 PM
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Ivy Mike, any chance you could post pictures of your SC and SS boards? It is best to test Vsus on there. The SC is on the left, SS on the right, when looking from the rear of the panel.
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Old 06-01-2013, 10:34 PM
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Absolutely.

Here's the left board.



And then on the right there are two so first one is upper, second is lower (pretty sure the lower is not what you're referring to though, but I'm including it in case).






Let me know if you need better detail of a certain area.
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Old 06-01-2013, 10:41 PM
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The bottom board is the A board, it's the one with the processor, ram, and so on. Won't need to do anything with that.

Also, from what I recall, I didn't see a VSUS point on the SS or SC boards. The only trimpot I found on any of the boards was the white one under the VSUS point on the power board.
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Old 06-02-2013, 05:48 AM
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Quote:
Originally Posted by tom669 View Post

My guess is related to the energy conversion from the discharge in the plasma cell to UV light. If the energy conversion is insufficient, I think it may be leading to an insufficient UV output. Increasing VSUS (breakdown voltage for plasma gas) puts more energy into the PDP, but it probably causes more of the energy to be in the lower UV band (lower energy), which leads to cyan tint. Decreasing VSUS reduces panel energy, reducing the higher band (higher energy) UV. That is from someone who specialises in electronic; physics isn't my specialisation.

And the reason blobs appear is because the panel gas is not totally even in all cells and the probability of an individual pixel successfully dischaging and emitting light is proportional to: energy added times gas concentration. Manufacturers try to set this at 99.999% or something high to avoid dead pixel problems. Uneven gas is not a problem if you make sure the cells have good phosphor coating, and each cell has the same amount because what determines the light output is the phosphors, not the amount of UV. The unconverted UV is simply wasted as invisible (harmless) light. Now, this may be one reason the red/pink/cyan blob pops up in recent models but tended to avoid older ones. As manufacturers try to improve panel efficiency they drop the energy going into the panel as much as possible, avoiding wasting too much as UV. If they go too far -- if you end up on the wrong end of the production bell-curve -- then you have the blob symptoms.

It's a complicated problem - the amount of UV generated photons depends not only on the primary gas ratios He/Xe but the partial pressure of Xe which is the primary emitter at 147, 150 and 173 nm. Changing the sustain voltage will not change the spectral distribution (i.e. ratio of 173/150 etc.) but can change total # of VUV photons emitted. Combine those variations with very thin phosphor layers that can have their own variability by sub-pixel and you can see how difficult it can be to maintain a uniform emission. Somehow Panny is pushing the envelope too hard, I've never seen/heard of a similar problem with Samsung PDPs.
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Old 06-02-2013, 04:31 PM
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D'oh. Vsus staring me in face on P board. You have a digital meter?
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Old 06-02-2013, 04:35 PM
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Quote:
Originally Posted by zoyd View Post

It's a complicated problem - the amount of UV generated photons depends not only on the primary gas ratios He/Xe but the partial pressure of Xe which is the primary emitter at 147, 150 and 173 nm. Changing the sustain voltage will not change the spectral distribution (i.e. ratio of 173/150 etc.) but can change total # of VUV photons emitted. Combine those variations with very thin phosphor layers that can have their own variability by sub-pixel and you can see how difficult it can be to maintain a uniform emission. Somehow Panny is pushing the envelope too hard, I've never seen/heard of a similar problem with Samsung PDPs.

Interesting. I wasn't aware manufacturers were using He/Xe? I thought they were still using Ne/Xe, with a touch of helium and nitrogen (the nitrogen for the memory portion of the display.)

I have definitely seen this fault on Samsung PDPs. For example, here is a PN51D6500, a 2011 model:
http://cdn.avsforum.com/9/9c/900x900px-LL-9cb3d789_DSC01574.jpeg
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Old 06-02-2013, 04:42 PM
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That's a diffusion (misfire) problem, not non-uniformity. There have been no reports that I'm aware of on this forum of any similar problem with samsungs.
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Old 06-02-2013, 04:43 PM
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Old 06-02-2013, 04:53 PM
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@zoyd: Non-uniformity, as in dirty screen effect? I have seen many Samsung, LG and Panasonic with that.
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Old 06-02-2013, 04:54 PM
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Quote:
Originally Posted by Ivy Mike View Post

Yes, this is the multimeter I'm using -

http://www.amazon.com/Equus-3320-Auto-Ranging-Digital-Multimeter/dp/B000EVYGZA/

OK, set the meter to DCV. Black probe goes on chassis of TV, any metal part. Red probe goes on VSUS test point. Tell us what you read.
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Old 06-02-2013, 04:59 PM
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Originally Posted by tom669 View Post

@zoyd: Non-uniformity, as in dirty screen effect? I have seen many Samsung, LG and Panasonic with that.

I was referring to the topic, non-uniformity in gray patterns, aka "blobs".
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Old 06-02-2013, 05:19 PM
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Quote:
Originally Posted by zoyd View Post

I was referring to the topic, non-uniformity in gray patterns, aka "blobs".

See I thought that was underdiffusion.
Perhaps due to the set cutting back the priming waveforms on dark scenes.
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Old 06-02-2013, 05:28 PM
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Quote:
Originally Posted by zoyd View Post

I was referring to the topic, non-uniformity in gray patterns, aka "blobs".

Then you haven't seen the replacement panel on my D7000. smile.gif I plan to remove the rear cover this week and check/adjust the voltages. Man, it looks like an awkward job for an old guy like me.

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Old 06-02-2013, 05:29 PM
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The blobs look to me like a materials problem because they are very smooth over rather large areas whereas under/over diffusion has a more statistical look with jagged patches where one of the sub-pixels is not firing but in smaller clumps and lines. That's how it looks on my display when I push the trims too hard.
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Old 06-02-2013, 05:34 PM
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Old 06-02-2013, 05:42 PM
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zoyd,

Well... on my panel there is a smooth pink relatively narrow vertical amorphous area on the left. Moving to the right, there is a wide vertical amorphous greenish area followed by a narrow pink one followed by a wide greenish one followed by a very prominent pink area. The areas are almost from top to bottom on the screen.

It is not caused by sub-pixel not firing. It is very similar to what I had on my Panasonic px80u. It is very annoying while watching B/W movies -- with the color control at zero.

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Old 06-02-2013, 05:42 PM
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Quote:
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shoot - I forgot about Larry's panel.

biggrin.gif

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