VSUS: Clear explanation please. - AVS Forum
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post #1 of 9 Old 07-29-2014, 12:25 AM - Thread Starter
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VSUS: Clear explanation please.

Can someone please explain what exactly is VSUS and how it effects the picture?

I did a thorough search in the AVS forums but I found a small explaination here and there by a user called tom669.

I want something more in depth.
Is there big longevity sacrifice to the panel (or other boards) life by making vsus higher?
How does it effect ABL?
I can see small (smaller than a pixel) random white discharges on a completely black background, will making VSUS higher fix this?
My picture is uniform without blobs or other discoloration, will I sacrifice something by raising the VSUS?
Some TV raise the VSUS automatically as the TV ages, why is that? Gas problems?

I have an ST60 and the only voltage I can change on the power board is VSUS, nothing else.
Why did Panasonic removed the option to adjust VAD to tweak the black level?

A lot of technical questions here, but I'm sure it'll help other users in the future when searching google for VSUS.
Even though Plasma's era is "over".


Thanks
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post #2 of 9 Old 07-29-2014, 09:34 AM
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Is there big longevity sacrifice to the panel (or other boards) life by making vsus higher? Yes, but the difference is negligible unless you go to extreme high values of Vsus (more than 20V from sticker rating.)

How does it effect ABL? It doesn't.

I can see small (smaller than a pixel) random white discharges on a completely black background, will making VSUS higher fix this? If anything it will make it worse. However what you are probably seeing is Panasonic's interleaved reset pulse discharge which is one method used to reduce black level. So changing Vsus would probably not affect it.

My picture is uniform without blobs or other discoloration, will I sacrifice something by raising the VSUS? Possibly - maybe, maybe not. In your case it would probably not fix your problem.

Some TV raise the VSUS automatically as the TV ages, why is that? Gas problems? I do not know of any TVs which do this. They may change VAD and priming waveform count, but only these.

I have an ST60 and the only voltage I can change on the power board is VSUS, nothing else. Why did Panasonic removed the option to adjust VAD to tweak the black level? 1) they were able to manufacture the panel to such a high degree of precision that they no longer required such adjustments, and 2) the A board controls the VAD adjustment as the panel ages dynamically

Even though Plasma's era is "over". It ain't over til the OLEDs become affordable!
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post #3 of 9 Old 07-29-2014, 11:01 AM - Thread Starter
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Thank you Tom.

A quick question:
Will changing the CPU board (A) for a different region (EU/US) work?
I have a European TV but I want to replace the A board to a US model which I bought from the US.
As I can see that the drivers (SC, SU, SD, SS, C1, C2, C3) are exactly the same.

Is the power board the same, considering its a switching mode PSU?

Last edited by James Freeman; 07-29-2014 at 11:35 AM.
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post #4 of 9 Old 07-29-2014, 02:00 PM
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Quote:
Originally Posted by James Freeman View Post
Thank you Tom.

A quick question:
Will changing the CPU board (A) for a different region (EU/US) work?
I have a European TV but I want to replace the A board to a US model which I bought from the US.
As I can see that the drivers (SC, SU, SD, SS, C1, C2, C3) are exactly the same.

Is the power board the same, considering its a switching mode PSU?
You should be able to only change the A board to convert the TV. However do be aware that Panasonic is particularly fond of also changing the mechanical dimensions between US & European TVs, so the case might not fit properly...!
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post #5 of 9 Old 07-29-2014, 09:35 PM - Thread Starter
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Thanks again.

I thought it would be good to have these here too:

Quote:
Originally Posted by tom669
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.
Quote:
Originally Posted by Moonchilde
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.
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post #6 of 9 Old 07-30-2014, 12:52 AM
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Tom, does lowering Vsus/Vs below factory spec also have the potential to have a negative impact on the panel/panel life or does that actually increase panel lifetime? THanks!
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post #7 of 9 Old 07-30-2014, 01:13 AM
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Quote:
Originally Posted by orion2001 View Post
Tom, does lowering Vsus/Vs below factory spec also have the potential to have a negative impact on the panel/panel life or does that actually increase panel lifetime? THanks!
If anything it'll increase lifetime, though I wouldn't expect a significant difference either way.
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post #8 of 9 Old 07-30-2014, 03:30 AM - Thread Starter
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Regarding orion2001's question,

When do we know where to stop the VSUS down-tuning?
When VSUS is tuned at the factory, what exactly the techs looking for (noise, dead pixels, coloration, etc...)?
In the factory, do the tech tune the vsus voltage to the minimum till there is no apparent artifacts on screen?
Will going a lot below nominal vsus voltage can the damage be permanent (end vise-versa)?

Last edited by James Freeman; 07-30-2014 at 03:38 AM.
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post #9 of 9 Old 07-31-2014, 12:33 AM
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When do we know where to stop the VSUS down-tuning? Usually it'll go pink tinted in the middle of the display or you will start seeing severe dead pixels and IR. In this case high or low Vs seems to cause dead pixels - go figure.

When VSUS is tuned at the factory, what exactly the techs looking for (noise, dead pixels, coloration, etc...)? In the factory, do the tech tune the vsus voltage to the minimum till there is no apparent artifacts on screen? It is done by characterising batches of panels now, so you will usually find each panel has the same voltages printed on it if it was made at the same approx time. In general they are looking for an image with no maldischarge, full discharge on white, and minimum power consumption. The required Vs is directly proportional to panel gas pressure. The early PDPs had Vs of 165V or so, but as the gas pressure racks up, Samsung has been leading the charge in high Vs. The F8500 has a nominal Vs of 221V which is also probably part of how it maintains such high brightness.

Will going a lot below nominal vsus voltage can the damage be permanent (end vise-versa)? Low Vs cannot cause harm. Potentially extreme Vs can cause damage to the panel via overheating which can include cracking the panel. However you would have to go to extreme values to cause this. I would not advise more than about 15V more than the panel sticker.
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