LG Plasma Panel tweaks for better blacks. - Page 9

Robert, If by APL you mean average picture level then how is this changed?

Has anyone noticed using these settings that color banding is now more prominent and also seems like on certain scenes looks like there is worse line bleeding?

No worries. I don't even own an LG. I'm just interested in PDP driving in general. APL is a percentage so you are correct that a reduction in black level will drop APL a very small amount. As for power and heat, it would be interesting if power consumption on a series of standard test patterns before and after adjustment was done.

Either way I think the physical panel itself (glass/phosphor) is perfectly safe regarding damage. The danger may lie in the driving boards, power supply, and other electrical components.

Second question for losservatore is did you reset to original settings first before using the order of adjustments on the other site or add them to your existing ones? Instructions seemed to indicate the order being pretty specific for a reason.

Also interestring was an update or additional tweak mentioned later in the same thread:

After father's LG was adjusted, my turn came. With the additional reduction of down-VS - controls the base voltage of the electrode arrays of horizontal panels, and is relevant to the background brightness in black - has a black level of the Road map in the off state must be equated. At the same time the colors are brilliant and the picture become clearer.

...and later using a meter:

With Oszi Set_Dn / SET_UP adjusted anything with a multimeter. At the end of the VS have fundamental voltage (202V) manually with simultaneous viewing of two images (totally black and white and black +5%) decreased. The re-measurement of the voltage VS yielded a value of 192V.

The lower the voltage is visible with the naked eye.

you're probably right, I have been overly critical viewing the past week.

"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."

Again, I have the above config on my PZ950 with set_up full throttle clockwise...no misfires. Has anyone done this exact tweak with the additional 2 pots with better results, or should I leave as is if too tricky/risky. I would like more pop if possible, now that blacks are deeper.

Thanks

I haven't noticed any on the pz950 as of yet

yes I went a little bit further with the pots to get better black levels,problems? well you will see some misfiring pixels in a cold start of your plasma like about 3 or 4 but after about 1 or 2 minutes the tv is back to normal,well another thin in order to get even more deeper blacks on my set I have to sacrifice two misfiringpixels,the two misfiringpixels turn back on in 24p mode so I can leave with that,remember that every plasma could behave different so you could get no missfiringpixels or could get one or two misfiringpixels, if you don't want to see then, just increase the levels of the set_down or set_up.

that behave of the 3 or 4 missfiring in cold start, started when I did the VZB POT
they go back to normal after 1 or 2 minutes if you dont want to see then just turn the VZB POT a little bit back almost to the normal position

The two missfiring pixels that doesn't go away is from the set_up and set_down If I want those back on I will have to go up with the set_up but the black levels will go up a little bit

BUT REMEMBER EVERY SINGLE PLASMA COULD BEHAVE DIFFERENT
maybe you wont get any misfiringpixels or you could get 1 or 2 thats if you want to go even lower.if you can leave with that no problem.

and remember that the 2 missfiring pixels they turn back on when I set the bd player to 24p mode.

I hope this will help

sorry for my english and if I miss some punctuation.

Hi Rob,

I agree with you 110%, it's just I feel the tweaks might have made pics slightly duller and wondering if any of the other 2 most recently mentioned pots, other than the 4 I used, can directly influence this. Again, maybe it's just me and admittedly have become SLIGHTLY OBSESSED (wife gonna do an intervention ) in pursuit of the most optimal PQ I can get.

Nope. Line bleeding is nearly invisible on my set and didn't notice anything out of the norm with color banding.

I had to lower my contrast, but raise my brightness.

Diddo. I don't see how anyone didn't have to raise brightness after pots tweak. Otherwise missing details in dark areas. Even after using Wizard (expert1), still have to raise brightness a couple a notches.

Raising the brightness level increases PWM noise, which is still a problem with LG plasmas.

The one thing that kind of bothers me with these LG plasmas is that when you're watching movies with black bars, the brightness of the picture kind of crawls into the black bars, making the top and bottom of the bars glow, which is pretty annoying when presented a full black screen.

I had some occasional moments where on startup, the screen is showing inky spots of pixels not being fired. Waiting for the power supply to reach optimum temperature, it all dissappears. Setting the POTS back to stock level does not fix this, so I have to live with that. Overall though, the picture is much much better than before.

You are correct. Tweaking the POTS does lower the generated heat from the panel. It's really a BIG difference with mine, I can now hold my hand on the back without getting burned

Which models? I have a PK950 and haven't noticed this.

i have a pk950, the black bars always glowed a bit gray. Really noticeable in dark scenes.

LG 50PV250 (EU model)

I did not change my brightnesssetting at all.

It woulkdn't be a good idea to do so, when you had the optimal blacklevelpoint already beforce the procedure, i.e. Black at "16" and "17" the first shade with pictureinformation.

Raising the brightness after that just sets the wrong blacklevelpoint and give you noise in shades that should be black.

With the potiruning you don't lose shadowdetail, actually it becomes more visible. The measured gamma of IRE5 rises (cause the colorimeter measures the noise and the black areas between the pwm spikes), which is a good thing, cause otherwise you would only reach 1.92 at IRE5, after the tweak I have 2.12

Also, the combination of the brightnesssetting and the R, G, B-setting of IRE5 is very uhm... special. There only exist one sweet spot, at which all shades at the very low end of the greyscale become different enough to render all detail.

On my german PK350 (the same as US PK550) it is "Brightness 54; Gamma High; IRE5 +5 -1 -2

well I don't have anything bad to said about this procedure,I just see awesome results in front of me...

Rob/Others

It has been mentioned a few times in this thread that using an oscilloscope would make the adjustment procedure easier and potentially more effective. I wonder if I could get some details as to how one would proceed using a scope.

The instructions below for adjusting Vs and Va using a voltmeter are clear, but the procedure using the scope is not. I am not sure what signal is being displayed in the diagrams where set UP/DN are being adjusted. Where does this signal appear on the board? What are the volts/div and sec/div on the axes? Are there any more details of the procedure in the training manual you are posting from?

Thanks for any help, and for collecting the various postings into this amazing thread.

Rich

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.

I also didn't had to alter the brightness, mine's at 50. I guess it depends on how you setup the TV. From out of my head I have Gamma at medium.
The black is indeed deeper and it doesn't get crushed. Watching a good HD documentary on Discovery HD or Nat Geo HD you can almost touch the grass/water/ice.
I didn't touch the pots on the powersupply (VA etc), mostly did tweaking on Setp_Up, Set_Down and Vy.
The only thing I notice (which was mentioned by some) is that when I just turn on the TV I see pixels (some sort of image retention) but as soon as there is an image it's gone and I don't see any weirdness when there's something on. I can live with that.