LG Plasma Panel tweaks for better blacks. - AVS Forum
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Old 11-12-2011, 05:41 AM - Thread Starter
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For the last few months there have been a few brave individuals who have begun the task of technically improving the black levels on their LG plasmas by tweaking a few pots on the actual boards inside the sets so I believe a dedicated thread should be started.
Mind you, all tweaks are at your own risk, will void your warranty and you could be exposed to lethal voltages, but the procedure could be rewarding.
And of course AVSFORUMS nor the posters can be held legally responsible for any mishaps, panel misbehavior and non-reversible disasters, proceed at your own risk.


Quote:
Originally Posted by rob80b View Post

http://en.wikipedia.org/wiki/Tweaking

"Tweaking
From Wikipedia, the free encyclopedia

This article is about hardware and software tweaking. For the drug-induced behavior, see Stereotypy. For other uses, see Tweaker (disambiguation).

Tweaking refers to fine-tuning or adjusting a complex system, usually an electronic device. Tweaks are any small modifications intended to improve a system.

In electronics, it is a synonym for "trimming." Analog circuit boards often have small potentiometers or other components on them that are used to calibrate or adjust the board as a service procedure: the small insulated screwdriver used to turn them is often called a "tweaker."
"

The posts that started it all

03-19-11, 12:23 PM
Quote:
Originally Posted by Turrican4D View Post

@rpauls
Simply put (my tuningmanual is in german), you have to turn the potis named "Set_UP" and "Set_Dn" clockwise until you get pixelmissfires and/or artifacts in the highlights.

Also it would show to help a minimum of MLL to turn the poti names "VY" completely counter clockwise and the poti names "VA" completely clockwise.

But beware! You lose your warranty!

And do it slow, in case you run in a safety shutdown of your TV.

05-24-11, 10:40 PM
Quote:
Originally Posted by Mauri View Post

All the documentation is available in U.S. english

This is the complete LG plasma Panel Alignment Book (quick reference), latest version (03/31/2011): http://136.166.4.200/contents/Displa...t_Handbook.pdf

LG U.S. got the explanations from the complete Training Manuals of many plasma models, and they have arranged that book. Read it carefully before start to do something. If you have never done such things before, it is better to have a look for an expert TV tech friend. The right way to arrange the tuning work, is to use a big mirror. Put the TV screen in front of the mirror and look at the mirror during tuning. Use only full plastic screwdrivers (easy available and very cheap) and remember that there could be high voltages on some circuits, so be careful. It is like to work on tube amps, you know? Only a bit more difficult because you are working on big screens, and that's the reason why you need to use a mirror (for safety reasons, at first).

For many plasma models, complete informations and training manuals (very useful) are also available. On this page there is the list: http://136.166.4.200/SubPages/Directview_PDP.htm

clic on the model you are interesting for, and on the left of the new page you will find the docs available for download. There is even the new 50PZ950 and PV450 models, as well as the PK950 and 750.

With such informations available, I think LG plasma are well worth a look. I'm going to buy a 60PK980 (same of 60PK950) during the next days. Now it has a very good price in my Country (1170 euro including shipping) and it is the right time to buy it. I'm not interesting in the actual 3D stuff.

'sorry for my bad english, and best regards from Italy
Mauri

05-21-11, 06:12 PM
Quote:
Originally Posted by Turrican4D View Post

No, it does not hurt the brightness of the picture. It only affects MLL.

The potis inside the TV are labeled with their names.

1. Start a Blu-ray-Disc

2. Turn "Va" full throttle clockwise

3. Turn Vy full throttle counterclockwise


After that turn "Set_Up" clockwise untill you get noise in very bright moviescenes. Turn a microamount counterclockwise untill the noise disappears.

Finally turn "Set_Dn" clockwise untill you get pixelmissfires. Turn a microamount counterclockwise untill you dont' get new pixelmissfires.

Congratulations to your new KURO (8G or 9G) MLL.


added Jan 5th 2012
Quote:
Originally Posted by wiremite View Post

I did get a kick out of tweaking my brother Bob's LG. Seeing in real tiime the grey bars turn pitch black was very satifying. The black level definitely matches (exceeds!?) my ST30 black levels. That a little analog knob could have so much control seems comical when you consider the advanced technology that gets poured into these panels.


Quote:
Originally Posted by Turrican4D View Post

Hehe

Even on my own PK350 I tried very different approaches. One method included Va full clockwise and the one I am using at this moment is the opposite-> Va full counterclockwise.

Each method has consequences for the other pots. If I set Va full clockwise, I cannot go so far with Set_Dn and I can't use Vs-Boost.

If I set Va full counterclockwise, I have more headroom for Set_Dn but a little less headroom for Set_Up but I can boost Vs a little bit, to make up for that, so that I have again the headroom for turning Set_Up more clockwise.

Generally are Set_Up, Set_Dn and Vy the only three of the seven pots, which have a direct influence on the black level.

Also generally there are three pots, which can cause vertical noise patterns-> Vs, Set_Dn and Vy.

One could say with Va full clockwise the danger of getting pixelmissfires out of a black screen to a bright screen (Disney Castle on Disney BDs for example) is not so high as it is with Va counterclockwise, but with counterclockwise the chance of getting missfires during an actual moviescene is lower.

If one decide to better just get some little pixelmissfires sometimes for getting even more out of his panel mll wise, he could experiment mit the pot VSC, cause with VSC at the right sweet spot, the ability of your panel to erase false fired pixels can be sped up.

VZB also has a sweet spot, that you can find the best with halflit secenes leike the one in "The American" ight at the sturt, when Clooney lies there with his soon to be dead girlfriend-> You turn VZB full counterclockwise: The picture will have lost its depth. Now you move slowly(!) micrometer for micrometer clockwise just to the point, where this moviescene jumps back to depth and contrast.

This is what you might get with the seven pots, if you set it too much clockwise or counterclockwise:

VZB____: noise (clockwise) or dullness (counterclockwise)
Vs_____: noisy whites/pixelmissfires (clockwise) or dullness/extreme pixelmissfires (counterclockwise)
VA_____: none obvious erros but possible pixelmissfires with static fullgreen screen (clockwise)
VSC____: None obvious errors or artifacts
Vy_____: noise/less MLL (clockwise) or better MLL (counterclockwise)
Set_Up_: pixelmissfires/better MLL (clockwise) or bad MLL (counterclockwise)
Set_Dn_: noise/better MLL (clockwise) or bad MLL


Added Nov 30th

http://www.avsforum.com/avs-vb/showt...php?p=21281625



Quote:
Originally Posted by harvro01 View Post

Just wanted to share my experience in doing these adjustments, I was hesitant to do it in the first place as I was concerned about what was actually happening, however I downloaded and read the factory manuals which explained a lot.

I have a 60PK550

The end result is WOW, what a difference. A fair bit of work tweaking various pots (I did all 7) but the end result is worth it. WAY deeper blacks, no difference in terms of noise or pixel misfires.

My experience with the various adjustments (and in the order I did them, following the factory LG sequence from the manual) is as follows:

VS: Counterclockwise results in some noise in lighter pixels and lowers MLL, turning clockwise corrects the pixel noise and raises MLL but too far clockwise, and my set just shuts off and will not restart. In the end, I only adjusted this pot a hair clockwise to get rid of the white pixel noise.
VA: Clockwise lowers MLL.Did not cause any misfires for me so mine is cranked fully clockwise.
VSC: Made no appreciable difference one way or the other to anything so mine is left at centre position.
Vy: Turning clockwise results in higher MLL, counterclockwise results in lower MLL. Does not appear to introduce any artifacts or noise so mine is cranked counterclockwise.
Set_Up: Clockwise lowers MLL. I've read that turning this fully clockwise can cause some pixel misfires, however this does not appear to be the case with my set, so mine is fully cranked.
Set_Down: Clockwise lowers MLL, however fully clockwise for me also introduces may pixel errors, pixels not resetting after changing colour, so I had to back mine off a bit from fully cranked clockwise until these disappeared.
VZB: Appears to affect the 'dullness' of the overall image, minimal effect on MLL that I can tell. Clockwise seems to give the picture more 'pop', while counterclockwise gives a more washed out image. Mine is cranked fully clockwise.

As others have said, I'm sure individual results differ, but for me, the few hours tweaking these pots and looking at test images and videos are well worth it. I would say that black letterbox bars are more or less gone and blend into the bezel now. Images seem to have way more pop and depth. I have never had any issues with image retention with my set (14 months old now) and nothing seems to have changed in this regard with the tweaks.

Initially, I was trying to follow the technical manual and adjust VS and VA to the voltages listed on my panel sticker as suggested. Mine were slightly off from the sticker. This however raised the MLL and so I just fiddled with pots to see what happened in the end. I'm glad I did.

Added December 8th 2011 http://www.avsforum.com/avs-vb/showt...php?p=21314111

Quote:
Originally Posted by walt73 View Post

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.

added December 20th 2011

Quote:
Originally Posted by rpauls View Post

When my 60PK540 was new it was measuring an MLL of .018 FtL for 60Hz inputs, which I was pretty happy with. However, now after a year of use I noticed the black level had risen quite a bit. Last night I measured it at .036 FtL (Never heard of LG MLL rise issues, so not sure what's up). In any event, I decided to try this pot tweak. The results were amazing.

I followed the LG training manual exactly.

First I measured all the voltages Vs, Va, Vy, VSC, VZB, and all were very close (within 1 volt) of the number on the panel sticker so I left them alone.

Then I got out the scope and locked on to the waveform as explained in the training manual. The Set Up portion of the waveform was supposed to be 280V, mine was measuring nearly 350V, the Set Down was supposed to be 140us long, mine was only 125us. I adjusted both pots until the readings were as close as possible to specs. I could only get Set up down to 290V even at full clockwise excursion, but I could get set down to exactly 140us, and both ramps in the waveform looked just like the picture. (Note, for all these measurements the set must be showing a full white 100% screen for at least 15 minutes)

Well I went back out front, turned off the whitewash and I the screen was so dark I thought it was off!

I got my probe out and it measured .008 FtL. Needless to say I am very happy with the results.

So in summary, I did not touch any of the 5 voltage pots, they were right on from the factory. I adjusted set up and set down only exactly as described in the manual and the results are amazing.

I will proceed to do a full grayscale and CMS calibration tonight and compare with my results with my measurements before the procedure, but I am very optimistic. The picture looks great.

Rich


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Old 11-12-2011, 05:48 AM - Thread Starter
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One could start here to see what's been done so far.

PZ950
http://www.avsforum.com/avs-vb/showt...9#post21131649
or here
PV450
http://www.avsforum.com/avs-vb/showt...5#post21155465

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Old 11-12-2011, 05:55 AM - Thread Starter
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Old 11-12-2011, 06:01 AM - Thread Starter
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Basic procedure, (not mine as I'll probably use a scope and voltage meter if I do proceed) as posted elsewhere.

Quote:
Originally Posted by Turrican4D View Post

No, it does not hurt the brightness of the picture. It only affects MLL.

The potis inside the TV are labeled with their names.

1. Start a Blu-ray-Disc

2. Turn "Va" full throttle clockwise

3. Turn Vy full throttle counterclockwise


After that turn "Set_Up" clockwise untill you get noise in very bright moviescenes. Turn a microamount counterclockwise untill the noise disappears.

Finally turn "Set_Dn" clockwise untill you get pixelmissfires. Turn a microamount counterclockwise untill you dont' get new pixelmissfires.

Congratulations to your new KURO (8G or 9G) MLL.


Robert
Toronto, Ontario
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Old 11-12-2011, 11:39 AM - Thread Starter
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Basic explanation for the set_up and set_down adjustments from the service manual to bring the black floor ( MLL) up but in our case down.
Quote:
Originally Posted by rob80b View Post

Simple explanation for the PK/PX950 but is the same for all panels.


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Old 11-12-2011, 11:43 AM - Thread Starter
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Bhazards photo explanation for his 60" PZ950

Quote:
Originally Posted by bhazard View Post

This is for the 60PZ950. The 50PZ might look different inside.

1. Start by removing ALL screws from the panel. The back piece will then pop off and look like this. Notice all the empty screw holes, there are around 30+ screws.



2. This is what the tv looks like with the back panel off. The arrow points to the board with the pots.



3. This is where Set_Up, Set_Dn, and Vy are located. Start with just adjusting Set_Up and Vy. Set_Up should go all the way clockwise or until artifacts appear. Vy should go a microturn to the left. Tweak Set_Dn clockwise if needed (try to not use it). Instant darker blacks. Have a mirror or someone watching the tv in a black bar scene to verify the blacks getting darker and no artifacts. Turn the tv off and on again to see if any artifacts appear during initial boot up.



4. Screw back piece back in. Done.


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Old 11-12-2011, 12:14 PM - Thread Starter
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Sarge19806 on his 450.
Quote:
Originally Posted by sarge19806 View Post

Eagle bluray 2:35:1 widescreen 1080/24p...black bars blend right in in dark room settings...gonna go out to walmart tomorrow and get orange and red led strips for ambient lighting...i heard it helps make the set even more for dark scene...if the pics dont do justice ill repost at a higher res on the camera...now time to put my surround sound back and enjoy...lol

for photos
http://www.avsforum.com/avs-vb/showt...1#post21009291

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Old 11-12-2011, 01:11 PM
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Now if only someone could come up with something for 2008-2011 Panasonic plasma owners!
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Old 11-12-2011, 01:39 PM
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Quote:
Originally Posted by katzman View Post

Now if only someone could come up with something for 2008-2011 Panasonic plasma owners!

there is. same type pot adjusting.
I haven't seen any new reports or confirmations.
It is under Pana rising blacks thread.
Long read, the info is in the last 1/4 of the thread.

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Old 11-12-2011, 02:09 PM
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im shopping around... this reaally makes that huge of a difference?
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Old 11-12-2011, 02:41 PM
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Interesting.

I always thought this kind of tweaking should be possible but I never read about actual stories. (But I recently read that "nobody could adjust the lifted Panasonic blacks back.)
I thought manufacturers may replaced the pots with digital voltage regulators (and the values aren't adjustable without re-programming the panel driver's EEPROM) or something...


Did anybody measure ANSI contrast after this adjustment?


Is there an equivalent method for Samsung D-series PDPs?

"DIY certified hobby-calibrator" (based on ChadB's "warning signs" list
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Old 11-12-2011, 03:08 PM
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im also curious of exactly how black these go after modz
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Old 11-12-2011, 03:49 PM
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Quote:
Originally Posted by rob80b View Post

For the last few months there have been a few brave individuals who have begun the task of technically improving the black levels on their LG plasmas by tweaking a few pots on the actual boards inside the sets so I believe a dedicated thread should be started.
Mind you, all tweaks are at your own risk, will void your warranty and you could be exposed to lethal voltages, but the procedure could be rewarding.

rob80b,

I have the LG PK550. It's about a year and a half old now. I calibrated it with my i1LT/color HCFR. Lately, about 1 minuite after turn on, the screen brightens quite a bit. Intelligent sensor is off. I wonder if after warm up, the settings shift requiring a re-adjustment of the pots. The blacks are not as dark as they once were. Can I do these adjustments on my set or is it strickly for the PZ series?
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Old 11-12-2011, 04:20 PM
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Post Edit:

So looking at the pdf for my 60ps11, I notice that the set_up and set_dwn are on the Y-SUS Panel Board but the VS and VA Adjustment knobs are on the SMPS Panel Board.

Are these the correct ones to adjust then per the instructions?
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Old 11-12-2011, 04:31 PM - Thread Starter
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Quote:
Originally Posted by keyoctave View Post

rob80b,

I have the LG PK550. It's about a year and a half old now. I calibrated it with my i1LT/color HCFR. Lately, about 1 minuite after turn on, the screen brightens quite a bit. Intelligent sensor is off. I wonder if after warm up, the settings shift requiring a re-adjustment of the pots. The blacks are not as dark as they once were. Can I do these adjustments on my set or is it strickly for the PZ series?

No reason it shouldn't, I'll be doing my 42PG25 from 2008 before my PX.
Check my third post for the link to all the LG plasma panel manuals to facilitate the location of the pots for your 550 on the Sus-board and power supply boards.
I believe it's the same as the PK250.
http://136.166.4.200/contents/Displa...50/50PK250.htm

Bear in mind though, I'm just the messenger until I actually do my own sets.

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Old 11-12-2011, 04:40 PM - Thread Starter
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Keep in mind though, if you're looking for Kuro blacks, Pioneer's panels were designed for the deepest blacks possible but at a price and I do not really believe it's possible with these current mass produced panels, although any improvement is welcome.

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Old 11-12-2011, 04:50 PM
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Quote:
Originally Posted by rob80b View Post

No reason it shouldn't, I'll be doing my 42PG25 from 2008 before my PX.
Check my third post for the link to all the LG plasma panel manuals to facilitate the location of the pots for your 550 on the Sus-board and power supply boards.
I believe it's the same as the PK250.
http://136.166.4.200/contents/Displa...50/50PK250.htm

Bear in mind though, I'm just the messenger until I actually do my own sets.

Thank you! I have downloaded the PK250 contents (yes, same as PK550). I will give this a go then do a full re-calibration. No, I don't expect Kuro blacks but any improvment would be welcome.

Btw, I had a 42PG20 prior to this set. Great sets for the money (at the time).
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Old 11-12-2011, 05:20 PM - Thread Starter
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Quote:
Originally Posted by keyoctave View Post

Thank you! I have downloaded the PK250 contents (yes, same as PK550). I will give this a go then do a full re-calibration. No, I don't expect Kuro blacks but any improvment would be welcome.

Btw, I had a 42PG20 prior to this set. Great sets for the money (at the time).

Here you go
http://www.avsforum.com/avs-vb/showt...6#post21170656

Quote:
Originally Posted by rb1213 View Post

Hi guys,

I just did the Pot trick on my 50PK550
adjusting only the Set_up (full clockwise)
& Vy (1mm counterclockwise)

al I can say is WOW what a difference almost Kuro Blacks
and no IR anymore.

Thanks for the info here


ps: I do put Nrgihtness a bit up now (54)
(was loosing some shadow details at 50)

Ciao


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Old 11-12-2011, 05:29 PM
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One more question.

After reading the different threads on this subject, it seems best to set ones blu-ray player with 24p OFF to do the adjustment, correct?
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Old 11-12-2011, 08:12 PM
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Quote:
Originally Posted by janos666 View Post

Did anybody measure ANSI contrast after this adjustment?

0.012 cd/m2 ANSI with PK350 aka 10000:1 contrast

Prof. Dr. Turrican M.D.
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Old 11-12-2011, 08:28 PM
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Quote:
Originally Posted by rob80b View Post

Keep in mind though, if you're looking for Kuro blacks, Pioneer's panels were designed for the deepest blacks possible but at a price and I do not really believe it's possible with these current mass produced panels, although any improvement is welcome.

Thats a fair assessment of the situation.
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Old 11-12-2011, 08:37 PM
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Quote:
Originally Posted by turrican4d View Post

0.012 cd/m2 ansi with pk350 aka 10000:1 contrast

.004 ?

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Old 11-13-2011, 04:34 AM
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Two different two-step methods are mentioned.

1. Set-Up clockwise
2. Vy a notch counterclockwise

and

1. Set-Up clockwise
2. VS a notch counterclockwise

Anyone compared the result of these two methods?
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Old 11-13-2011, 06:46 AM - Thread Starter
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We really need a Tech on board to explain in layman's terms the DC voltage offsets, but if I understand correctly the VA in conjunction with the VS are the adjustments for min and max DC voltage for each panel before being sent to the Sus-board where the Set_up, and Set_down adjust the vertical (voltage) and horizontal (timing) excursion of the waveforms and the VY the negative excursion.
If you can imagine a picture frame our goal is to max out the width and height of those waveforms and the timing within the confines of the frame, otherwise the waveform is distorted and anomalies will occur.
Again I encourage everyone to read the service manual and ideally using an oscilloscope would facilitate the adjustments, as it stands now we're doing open heart surgery without an EKG hooked up to the patient to monitor the results.


Robert
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Old 11-13-2011, 10:04 AM
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I tried it on my 850u Panasonic and ended up having a service tech come out and replace a board! Luckily I had bought an extended warranty. No place for idiots like me to play!
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Old 11-13-2011, 01:18 PM
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Quote:
Originally Posted by keyoctave View Post

One more question.

After reading the different threads on this subject, it seems best to set ones blu-ray player with 24p OFF to do the adjustment, correct?


I have a 60pv450 and used 60hz source material first, and had to re adjust later because 24p actually lowers the MLL and I had misfires.
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Old 11-13-2011, 01:40 PM
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Quote:
Originally Posted by katzman View Post

I tried it on my 850u Panasonic and ended up having a service tech come out and replace a board! Luckily I had bought an extended warranty. No place for idiots like me to play!

sorry to hear that.
can you be more specific about what you did and what board was changed?


Looks like the LGs get really nice after the adjustments.

Loving D65
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Old 11-13-2011, 02:13 PM
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Quote:
Originally Posted by CalWldLif View Post

.004 ?

0.00357 ftl


EDIT: The main reason, why LG throw so much room for good MLL away is the way, the power supply works after a cold start of the set. Depending on room temperature it takes the power supply up to two minutes to reach full throttle.

So LG goes the safe way to avoid pixel missfires after a cold start.

Prof. Dr. Turrican M.D.
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Old 11-13-2011, 02:22 PM - Thread Starter
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Quote:
Originally Posted by Turrican4D View Post

0.00357 ftl


EDIT: The main reason, why LG throw so much room for good MLL away is the way, the power supply works after a cold start of the set. Depending on room temperature it takes the power supply up to two minutes to reach full throttle.

Which why LG insists on a minimum 10 minute warm up before adjustments.

Robert
Toronto, Ontario
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Old 11-13-2011, 02:54 PM
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Quote:
Originally Posted by Turrican4D View Post

0.00357 ftl


EDIT: The main reason, why LG throw so much room for good MLL away is the way, the power supply works after a cold start of the set. Depending on room temperature it takes the power supply up to two minutes to reach full throttle.

So LG goes the safe way to avoid pixel missfires after a cold start.

very respectable.
Very nice it can be achieved.

Loving D65
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