LG Plasma Panel tweaks for better blacks. - Page 12 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #331 of 1397 Old 12-05-2011, 04:20 PM
AVS Special Member
 
xrox's Avatar
 
Join Date: Feb 2003
Posts: 3,169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 50
Quote:
Originally Posted by rob80b View Post

But my original inquiry was from reading LGs paper, it looks like resolution is also a contributing factor, not too sure how this applies to the up-scaling algorithms so my theory could be incorrect.
"[0008] In the PDP adopting the sub-field driving method, the brightness is determined by the display interval, that is, the discharge sustaining interval. Since a relatively long time is wasted due to the address interval allocated equally for each sub-field SF1 to SFn, however, a time allocated for the discharge sustaining interval determining the brightness lacks. For instance, when 480 lines are scanned by a scanning voltage pulse with a width of 3.m in the address interval of each sub-field, a time of about 1.44ms is required. Accordingly, since a time of about 12ms (i.e., 1.44ms×8) is allocated for the total address interval when 16.7ms is allocated for on frame display interval consisting of 8 sub-fields so as to display a 8-bit image data, a time of about 4ms is allocated for the discharge sustaining interval except for the reset interval. As a result, the conventional PDP has a problem in that the brightness is low due to a relative lack of the discharge sustaining interval determining the brightness. Furthermore, when it is intended to implement a screen with a high resolution, a discharge sustaining interval becomes more lack due to an increase in the address interval according to an increase in the scanning lines to make the display itself impossible."
https://data.epo.org/publication-ser...iDocId=4997940

That quote is describing the effect of the number of panel subpixels on brightness. Absolutely nothing to do with source resolution.

They are saying that more panel subpixels means more "time" is required to send data to all of them and thus less time is available to emit light. Since PDPs control brightness via "time" (i.e.- PWM), if there is less time to emit light then the panel is less bright.

In other words they are saying a 480p PDP display is brighter than a 1080p PDP display. Source is irrelevant.

Over thinking, over analyzing separates the body from the mind
xrox is offline  
Sponsored Links
Advertisement
 
post #332 of 1397 Old 12-05-2011, 07:51 PM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Quote:
Originally Posted by xrox View Post

That quote is describing the effect of the number of panel subpixels on brightness. Absolutely nothing to do with source resolution.

They are saying that more panel subpixels means more "time" is required to send data to all of them and thus less time is available to emit light. Since PDPs control brightness via "time" (i.e.- PWM), if there is less time to emit light then the panel is less bright.

In other words they are saying a 480p PDP display is brighter than a 1080p PDP display. Source is irrelevant.

Got it.

I was thinking that resolution might have had a similar effect but in an opposite way, even though the number of pixels remain the same, more data from the source might maintain a better sustain period, which I guess in effect is what was mentioned by rpuals above regarding refresh rate.

Still learning

Thanks Guys

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #333 of 1397 Old 12-05-2011, 08:30 PM
AVS Special Member
 
rpauls's Avatar
 
Join Date: Nov 2006
Posts: 1,192
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by rob80b View Post

Hi rpuals

Yes that I'm aware of that, by increasing the brightness it also makes black look darker in most regular lit scenes therefore increasing the contrast ratio but adversely makes dark scenes look grayer, unless we lower the MLL.

But my original inquiry was from reading LGs paper, it looks like resolution is also a contributing factor, not too sure how this applies to the up-scaling algorithms so my theory could be incorrect.
"[0008] In the PDP adopting the sub-field driving method, the brightness is determined by the display interval, that is, the discharge sustaining interval. Since a relatively long time is wasted due to the address interval allocated equally for each sub-field SF1 to SFn, however, a time allocated for the discharge sustaining interval determining the brightness lacks. For instance, when 480 lines are scanned by a scanning voltage pulse with a width of 3.m in the address interval of each sub-field, a time of about 1.44ms is required. Accordingly, since a time of about 12ms (i.e., 1.44ms×8) is allocated for the total address interval when 16.7ms is allocated for on frame display interval consisting of 8 sub-fields so as to display a 8-bit image data, a time of about 4ms is allocated for the discharge sustaining interval except for the reset interval. As a result, the conventional PDP has a problem in that the brightness is low due to a relative lack of the discharge sustaining interval determining the brightness. Furthermore, when it is intended to implement a screen with a high resolution, a discharge sustaining interval becomes more lack due to an increase in the address interval according to an increase in the scanning lines to make the display itself impossible."
https://data.epo.org/publication-ser...iDocId=4997940

This quote is really interesting. For one thing, it sounds like the number of sub fields is equal to the number of bits in the pixel data (in this case 8). I did not know this. In fact, I really don't know much about how the panels actually operate and also an still learning.

The second thing that jumps out is the effect of refresh rate. They state that for 8-bit data it takes about 12 ms to service the 8 sub fields and since there is 16.7 ms allocated per frame (at 60 HZ) there is left 4ms for the discharge sustaining interval except for the reset interval. Now if we refresh at 72Hz for a 24p movie the time per frame drops from 16.7ms to 13.9ms (1/72). This would leave only 1.9 ms for the discharge sustaining interval. What deleterious effect might this have on the image? Is this related to the reason why 24p feeds have a higher MLL?
rpauls is offline  
post #334 of 1397 Old 12-05-2011, 09:09 PM
AVS Special Member
 
xrox's Avatar
 
Join Date: Feb 2003
Posts: 3,169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 50
Quote:
Originally Posted by rpauls View Post

This quote is really interesting. For one thing, it sounds like the number of sub fields is equal to the number of bits in the pixel data (in this case 8). I did not know this. In fact, I really don't know much about how the panels actually operate and also an still learning.

The second thing that jumps out is the effect of refresh rate. They state that for 8-bit data it takes about 12 ms to service the 8 sub fields and since there is 16.7 ms allocated per frame (at 60 HZ) there is left 4ms for the discharge sustaining interval except for the reset interval. Now if we refresh at 72Hz for a 24p movie the time per frame drops from 16.7ms to 13.9ms (1/72). This would leave only 1.9 ms for the discharge sustaining interval. What deleterious effect might this have on the image? Is this related to the reason why 24p feeds have a higher MLL?

Firstly, it is describing a very old PDP system. At the most I would just use it as a reference for basic learning.

Secondly, to answer your questions, in your example the panel brightness would be reduced because the total sustain period has dropped from 4ms to 1.9ms. In reality, a 72Hz capable panel would have either a dual scan system or like modern panels have single scan with faster addressing (e.g. - much less than 12ms).

Over thinking, over analyzing separates the body from the mind
xrox is offline  
post #335 of 1397 Old 12-05-2011, 10:52 PM
Senior Member
 
TXSTYLE's Avatar
 
Join Date: Jun 2003
Location: Plano, TX
Posts: 226
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
______________________________________
LL

My Home Theater = Investment In My Entertainment!
TXSTYLE is offline  
post #336 of 1397 Old 12-05-2011, 11:24 PM
Advanced Member
 
Turrican4D's Avatar
 
Join Date: Dec 2009
Posts: 606
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Quote:
Originally Posted by rob80b View Post

Comparing some films I've seen it more pronounced on my brother's Panasonic ST30 than my PX950 for example.

Now, THAT's interesting! Since having a couple of S10-plasmas (S1 in the USA) in 2009 I always thought of Panasonic to be superior with the pwm noise in the grey shades near black.

Besides beeing finer, the noise appeared as neutral grey to me.

So Panasonic got worse regarding this issue in the year 2011 versus the year 2009?

P.S.: I tuned Vs a little notch down and have the feeling, that the clumpy pwm noise near black is less obvious than before ("Marley is dead"-chapter in "A Christmas Carol" for example).

Also on the same time, I have the feeling, that I can see details in that secene more easily, but this is probably just, that my pupils keep a little bit wider than beforce, cause reducing the Vs lowers the light emission of the cells.
Turrican4D is offline  
post #337 of 1397 Old 12-05-2011, 11:26 PM
Advanced Member
 
Turrican4D's Avatar
 
Join Date: Dec 2009
Posts: 606
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Quote:
Originally Posted by losservatore View Post

I notice that after been tweaking the tv for a couple of weeks that the VZB POT is responsible of giving more punch to the colors, you will get more color pop with the VZB POT also will lower some mll.


My set has a sweet spot regarding the VZB. Turning it anymore than that clockwise changes nothing for the PQ on my set.

The more I keep it counterclockwise, the more headroom I have for Set_UP though.
Turrican4D is offline  
post #338 of 1397 Old 12-05-2011, 11:33 PM
Advanced Member
 
Turrican4D's Avatar
 
Join Date: Dec 2009
Posts: 606
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Quote:
Originally Posted by Goatse View Post

all plasma has green dancing dots, its how plasma makes dark colors. LG seems more prone than most though. If you crank the brightness over 50, you'll see green dancing dots on the black bars also. But at 50 it crushes details, no amount of pots tweak would make the green dots go away at 59 brightness where its should be.

Hmmm, on my german PK350 there is one (only one) right combination ob

a) Gamma

b) Brightness

c) R, G, B of IRE5

On that sweet spot (again ), which is Gamma High, Brightness 54 and IRE5 at +5 -1 -2...

a) Black bars are always black

b) No black crush in the image itself

c) all different shades of grey from 17 up to 25 are perfectly distingushable from each other.



P.S.: Just found out, how bad line bleeding is n Panasonic GT30 and VT30! LG had the problem last year, but the PZ-models, like PZ250, PZ550 and PZ950 seem to not have any light bleed.

Screen filters aside, in a dark room a tuned and calibrated PZ250 should be a more than worthy opponent to a calibrated VT30.
Turrican4D is offline  
post #339 of 1397 Old 12-05-2011, 11:36 PM
Advanced Member
 
Turrican4D's Avatar
 
Join Date: Dec 2009
Posts: 606
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Quote:
Originally Posted by rpauls View Post

We are talking about refresh rate, not resolution. When the LG displays an input that is in 24p (true film mode) it shows each frame three times (24 * 3 = 72Hz).

It's 96hz (4 * 24) for germany.

The best MLL I have in 60hz, secondbest in 24p and 50hz (our broadcast over here) comes in third.
Turrican4D is offline  
post #340 of 1397 Old 12-05-2011, 11:49 PM
Advanced Member
 
Turrican4D's Avatar
 
Join Date: Dec 2009
Posts: 606
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
Quote:
Originally Posted by *MaDJiK* View Post

I guess it depends on the settings and encoding of the source. I'm not an expert but I know there is for example sRGB 16-235 (the default on DVD if I remember well) and sRGB 0-255 (BluRay, still if I remember well) which render a more contrasted image with better blacks.

Nope.

Videolevel (16-235) is used on almost all sources! You must set your blu-ray-player for example to "RGB Standard".

0-255 is only PC Level.

Important: If you set "Blacklevel from Low to High" and back again, you have to change the HDMI1 to 2 or from 2 to 1, otherwise the whole greyscale of the TV is confused!


EDIT: 16-235 versus 0-255 has nothing to do with black level (MLL)! It's only the range from black to white. The correct shade for black is normally 16 and for PCs it is "0" (zero). White is 235 for videolevel and 255 for PC level

236 up to 255 is also used in video level thogh. It is the range from white (235) up to whiter than white.

Never use 0-255 (High) on Blu-ray!
Turrican4D is offline  
post #341 of 1397 Old 12-06-2011, 03:31 AM
 
losservatore's Avatar
 
Join Date: Jan 2011
Location: Ohio
Posts: 2,946
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 97 Post(s)
Liked: 228
I wrote about a week ago, that you will get with the VZB POT more color punch plus the mll will lower too a little bit, well that is true (((but))) your whites will start to look like a beige color,I have to let this know,I notice this alot on the movie sin city,,so I turn the VZB to its original position also I did the same with the VSC,both the VSC and VZB are now in there original position,,,,I recommend to stay away of those to POTS and just follow the safe tweak.


MODEL:LG 60 PK550
losservatore is offline  
post #342 of 1397 Old 12-06-2011, 03:59 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Quote:
Originally Posted by losservatore View Post

I wrote about a week ago, that you will get with the VZB POT more color punch plus the mll will lower too a little bit, well that is true (((but))) your whites will start to look like a beige color,I have to let this know,I notice this a lot on the movie sin city,,so I turn the VZB to its original position also I did the same with the VSC,both the VSC and VZB are now in there original position,,,,I recommend to stay away of those to POTS and just follow the safe tweak.

Thanks for the observation.
Those pots are most likely adjusting contrast, so those tweaking for better pop may be just adjusting the contrast so access is probably better left to just using the remote funtions.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #343 of 1397 Old 12-06-2011, 04:17 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Quote:
Originally Posted by Turrican4D View Post

Hmmm, on my german PK350 there is one (only one) right combination ob

a) Gamma

b) Brightness

c) R, G, B of IRE5

On that sweet spot (again ), which is Gamma High, Brightness 54 and IRE5 at +5 -1 -2...

a) Black bars are always black

b) No black crush in the image itself

c) all different shades of grey from 17 up to 25 are perfectly distingushable from each other.



P.S.: Just found out, how bad line bleeding is n Panasonic GT30 and VT30! LG had the problem last year, but the PZ-models, like PZ250, PZ550 and PZ950 seem to not have any light bleed.

Screen filters aside, in a dark room a tuned and calibrated PZ250 should be a more than worthy opponent to a calibrated VT30.

Quote:
Originally Posted by Goatse View Post

all plasma has green dancing dots, its how plasma makes dark colors. LG seems more prone than most though. If you crank the brightness over 50, you'll see green dancing dots on the black bars also. But at 50 it crushes details, no amount of pots tweak would make the green dots go away at 59 brightness where its should be.

On my stock PX950 the sweet spot is around 49-50 for the brightness control, at that point black the bars are perfectly uniform, it's also the point were I had adjusted the brightness for the best perceived picture without thinking about pixel noise, so it sort of worked out.
After tweaking my PG25 I used the VA, slightly clockwise to remove dancing green pixels and they will not appear until the brightness is above 60 or more so I actually have more head room as I keep the PG at around 50 also, keep in mind though that the PG25 is only 720dpi and most likely reacts differently to adjustments.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #344 of 1397 Old 12-06-2011, 04:23 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Quote:
Originally Posted by xrox View Post

Firstly, it is describing a very old PDP system. At the most I would just use it as a reference for basic learning.

Exactly.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #345 of 1397 Old 12-06-2011, 05:11 AM
Advanced Member
 
Turrican4D's Avatar
 
Join Date: Dec 2009
Posts: 606
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 11
I wonder, why noone over there in the D550-thread bothers, to open his set. Maybe it's possible with the Samsungs also.

In the Samsung service manual there is nothing written of pots, but who knows?
Turrican4D is offline  
post #346 of 1397 Old 12-06-2011, 05:44 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Quote:
Originally Posted by Turrican4D View Post

I wonder, why noone over there in the D550-thread bothers, to open his set. Maybe it's possible with the Samsungs also.

In the Samsung service manual there is nothing written of pots, but who knows?

That will be you're next crusade.
But seeing it was you who started us all in the pursuit of better black for our LGs (at least on this side of the Atlantic) we might need you just a bit longer.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #347 of 1397 Old 12-06-2011, 05:38 PM
Member
 
derod68's Avatar
 
Join Date: Jul 2011
Posts: 171
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Just a suggestion to all...

If someone is posting some feedback on a good or bad result of a pots tweak, please write the type/model of set. That would help us all in IMHO.

derod68 is offline  
post #348 of 1397 Old 12-06-2011, 05:47 PM
Member
 
derod68's Avatar
 
Join Date: Jul 2011
Posts: 171
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Quote:
Originally Posted by Turrican4D View Post

My set has a sweet spot regarding the VZB. Turning it anymore than that clockwise changes nothing for the PQ on my set.

The more I keep it counterclockwise, the more headroom I have for Set_UP though.

On the PZ950, the VZB only turned a hair clockwise then maxed out. Don't know if just my PZ?

I was already able to turn Set_Up full throttle clockwise with no negatives before the VZB tweak with the Vy and VA according to your instructions with the blu-ray. Still haven't touched VS. what would the VS do exactly and which way turn?
derod68 is offline  
post #349 of 1397 Old 12-07-2011, 01:58 AM
Newbie
 
marcuse1979's Avatar
 
Join Date: May 2011
Posts: 8
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 12
Quote:
Originally Posted by derod68 View Post

. Still haven't touched VS. what would the VS do exactly and which way turn?

I'm also interested in that. I touched it and it just caused vertical lines appearing all around, it has a narrow range where you can adjust it.

I don't know very well what Set_dn does (and which way move it towards), it didn't help with MLL, but pixel missfires appeared.

And Turrican4D, do you keep adjusting VA full counterclockwise? Does it have some contribution to MLL? I think it just gives more room to Set_up, but I didn't notice much difference from being full left or full right.

Thanks
marcuse1979 is offline  
post #350 of 1397 Old 12-07-2011, 04:24 AM
Advanced Member
 
MitchR's Avatar
 
Join Date: Jan 2007
Posts: 635
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
The VZB pot does nothing but worsen the picture. If turned clockwise it will accentuate IR, if turned counterclockwise it will introduce pixelmissfires and a dull looking picture. I would leave it where it is.
MitchR is offline  
post #351 of 1397 Old 12-07-2011, 05:59 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
The VZB interacts with the Sustain Electrode Z during the Address period, maybe xrox or Turrican have some insight, to enlighten us, on how it interacts with the Scan Electrode Y where we have our Set_up and Set-dn (Reset Period) and the Vy/Vcs (Address period) pots.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #352 of 1397 Old 12-07-2011, 07:31 AM
AVS Special Member
 
xrox's Avatar
 
Join Date: Feb 2003
Posts: 3,169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 50
Quote:
Originally Posted by rob80b View Post

The VZB interacts with the Sustain Electrode “Z” during the Address period, maybe xrox or Turrican have some insight, to enlighten us, on how it interacts with the Scan Electrode “Y” where we have our Set_up and Set-dn (Reset Period) and the Vy/Vcs (Address period) pots.

I can only speculate based on the patent and waveform plots I have. As I said, unless we obtain the entire waveform for one frame period we can only speculate.

The Vzb and Vsc look like bias voltages applied to ensure addressing discharge prevent discharge between the Z and Y electrodes. If you look at the waveform plots I posted earlier this shows this clearly as the Vzb is slightly biased from the Vz and the Vsc is slightly biased from GND to augment the Scan voltage pulses.

If you adjust either Vzb or Vsc you risk an address failure which would create a black pixels or bright sparkles.

Additionally the Vzb seems to be used also in the Set-down period which means adjustment of this could lead to loss of pixel control (on or off).

Edit: I looked it up and changed the reasoning

Over thinking, over analyzing separates the body from the mind
xrox is offline  
post #353 of 1397 Old 12-07-2011, 08:09 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Quote:
Originally Posted by xrox View Post

I can only speculate based on the patent and waveform plots I have. As I said, unless we obtain the entire waveform for one frame period we can only speculate.

The Vzb and Vsc look like bias voltages applied to ensure addressing discharge prevent discharge between the Z and Y electrodes. If you look at the waveform plots I posted earlier this shows this clearly as the Vzb is slightly biased from the Vz and the Vsc is slightly biased from GND to augment the Scan voltage pulses.

If you adjust either Vzb or Vsc you risk an address failure which would create a black pixels or bright sparkles.

Additionally the Vzb seems to be used also in the Set-down period which means adjustment of this could lead to loss of pixel control (on or off).

Edit: I looked it up and changed the reasoning

That’s the conclusion I had deducted with my limited knowledge of plasma sets by looking at the chart, as you mentioned, without seeing “the entire waveform for one frame period we can only speculate”.
What I’m not clear on is; the ramp waveform from the Set_up, Set_dn, is it the waveform for the PWM, or the PWM is another waveform which triggers the duty cycle for the Ramp waveform.
I’m only going from knowledge of Analogue synthesis, but basically PWM (pulse width modulation) is a continually cycling waveform used to automatically control (vary) voltage controlled amplification and can also be used to repeatedly alter the shape of the main waveform while it is being sustained.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #354 of 1397 Old 12-07-2011, 08:11 AM
Senior Member
 
TXSTYLE's Avatar
 
Join Date: Jun 2003
Location: Plano, TX
Posts: 226
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Ya'll are sime brave souls....

Sometimes things may be better left alone.

Waiting to get my PZ950. I wull tweak it bwst I can through settings and live with tge rest....

My Home Theater = Investment In My Entertainment!
TXSTYLE is offline  
post #355 of 1397 Old 12-07-2011, 08:17 AM
AVS Special Member
 
xrox's Avatar
 
Join Date: Feb 2003
Posts: 3,169
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 50
Quote:
Originally Posted by rob80b View Post

That's the conclusion I had deducted with my limited knowledge of plasma sets by looking at the chart, as you mentioned, without seeing the entire waveform for one frame period we can only speculate.
What I'm not clear on is; the ramp waveform from the Set_up, Set_dn, is it the waveform for the PWM, or the PWM is another waveform which triggers the duty cycle for the Ramp waveform.
I'm only going from knowledge of Analogue synthesis, but basically PWM (pulse width modulation) is a continually cycling waveform used to automatically control (vary) voltage controlled amplification and can also be used to repeatedly alter the shape of the main waveform while it is being sustained.

One light pulse of the PWM is created during the sustain period of one subfield. The width of that pulse is determined by the number of sustain discharges during that period.

Over thinking, over analyzing separates the body from the mind
xrox is offline  
post #356 of 1397 Old 12-07-2011, 08:33 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Looking at the graph below turning the Set_dn changes the duty cycle (width) of the Ramp waveform's negative cycle, which would throw the timing (triggering) off with the Sustain Electrode Z needing adjustment with the Vz and Vzb pots to correct the timing, how we would do this correctly without a scope or other measuring equipment I'm not sure, so yes it is better left alone.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #357 of 1397 Old 12-07-2011, 08:37 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Quote:
Originally Posted by xrox View Post

One light pulse of the PWM is created during the sustain period of one subfield. The width of that pulse is determined by the number of sustain discharges during that period.

Thanks xrox.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #358 of 1397 Old 12-07-2011, 08:43 AM
AVS Special Member
 
bhazard's Avatar
 
Join Date: Nov 2006
Location: NY
Posts: 2,409
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 36
The best part about this tweak, is that no one has bricked their tv in doing it (knock on wood).
bhazard is offline  
post #359 of 1397 Old 12-07-2011, 09:11 AM - Thread Starter
AVS Special Member
 
rob80b's Avatar
 
Join Date: Sep 2007
Location: Toronto, Ontario
Posts: 1,512
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Liked: 29
Quote:
Originally Posted by bhazard View Post

The best part about this tweak, is that no one has bricked their tv in doing it (knock on wood).

True, but once we nail down how to control the X Address Electrode, the Y Scan Electrode ( Set_up, Set_Dn, Vsc and Vy ) and the Z Sustain Electrode (Vz and Vzb) and their associated Periods, Pre-reset, Reset-Address and Sustain in conjunction with the Power Supply board adjustments VS and VA we will be all set.

Robert
Toronto, Ontario

 

https://myspace.com/151752802/videos

rob80b is offline  
post #360 of 1397 Old 12-07-2011, 11:07 AM
Senior Member
 
walt73's Avatar
 
Join Date: Mar 2009
Posts: 330
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I did the tweak on my 50PK550 (North American model, Mar 2010 build) this morning with stunning results (so far).

Following the tips in this thread, I adjusted only VY and Set_Up. Factory presets were 4 and 1 o'clock respectively; I started by turning these to 2 and 7 o'clock (i.e. Set_Up maxed out). Wow! Massive instant improvement! Turned TV off and allowed to cool 45 mins. TV back on, again v deep black level ... BUT suddenly saw too many misfiring pixels (unacceptably noisy-looking picture).

I decided to proceed as follows: sit at my preferred view distance (lately 63") and then throttle back VY and Set_Up, not necessarily til absolutely no pixels misfired, but only until I judged the results to be tolerable in actual viewing. (I figured I was willing to trade off a certain amount of picture noise for better black level -- exactly how much noise, to be discovered by experiment.)

I did all tests in 72Hz mode since on my set the MLL is visibly better than it is in 60Hz. I know in theory it should be the other way round but I'm not the first to report this on the 50" model of the PK550. To get the colour bar patterns, played on PS3, converted to 1080p24 I used an outboard video processor (DVDO Edge); I also tried some HD cable movies and of course Blu-rays.

Eventually I settled into VY 3 o'clock and Set_Up 5 o'clock. If I look very very hard (from 63" away) at the blue and red on the colour bar pattern I can still sometimes barely see the occasional misfiring pixel. BFD; black levels are now insanely good, and besides, I can't see the misfiring at all during a movie. With my bias light on (GE 20W Daylite flourescent strip 6500K) black appears almost as black as the bezel. I don't have a light meter so I can't say what the MLL is exactly. Suffice it to say it's pretty freakin' black. If I wanted to I could probably watch this set in the dark. (I couldn't before the tweak; MLL was way too high for that.)

I watched half of Sin City Blu-ray and was utterly floooooored by the new improved contrast. Other PQ-demanding films which instantly went from blah to wow: Dracula (Coppola), The Spirit, dark scenes in Pirates/Caribbean #1. Can't wait to try more.

I'd like to say a huge thank you to the contributors to this thread. What an awesome tweak. I will post back if I run into any issues in future.

PS: 50PK550 owners: As you remove the back cover watch out for the mini screws around the component video inputs; they're easy to overlook. Ditto for the lone screw near the HDMI ins and the one by the power socket.

"... we wonÂt be stopping plasma production any time soon. We see it going on for another ten years." -- Kevin Lee, VP, Smart TV Partnerships (Samsung), 1/7/11
walt73 is offline  
Reply Plasma Flat Panel Displays

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off