LG Plasma Panel tweaks for better blacks. - Page 28

I want to report that after two days of using the best method of turrican tweak the mll did rise like he stated,I want to try his other method but not sure what he means about Y board and lvds cable,he means Y susboard ?lvds cable from where? there so many cables...

I checked my black levels last night. The spyder 2 gave no reading for IRE 0, but does look pitch black. Next, I used AVC HD windows for IRE 10, 20, etc. and measured only the black area instead. MLL for 60hz = 0.024 ftL
MLL for 24 hz = 0.018 ftL
Is that the correct way to check MLL? If so then I'll have to tweak again someday. This stuff never ends, don't you love it :P.

Yeah, that should definitely work for measuring MLL. What it sounds like you are encountering is the situation where when the TV has no input (i.e., 0% test case) the display is turning off. Off is different than MLL. A good way to trick the TV into staying on is to do as you did and send some other minor illumination to another part of the screen that is not under your probe.

What TV is this?

I have a 50pk550 Jan 2010 build. Set_up did not have much headroom, went from 11 o'clock to 12 o'clock position only. I'll have to reopen one day to measure and readjust voltages to see if there's some more headroom available.

for a 50PK550 I suspect you can get lower MLL than this for at least one of the refresh rates after adjustment. I can't say for sure, however, since I have the 60 inch version, but I was able to get the MLL easily below .008, and even lower if I accepted some pixel misfires.

Of course these light levels are so low we may be hitting the sensitivity limits of the probes. I used the Eye1 D2, which should be fairly accurate for Luminance in this range, not sure about the low light accuracy of the Spyder 2. I also have an Eye1 Pro, but it is impossible to measure accurately this low with this. Did you take any MLL measurements before you did the adjustments?

50PK760 here it's a French version of the UK 790, which has the infinia design but lacks the true black filter of the PK990.

Got it from Pixmania as they ony seemed to sell the PK350 and 250 here in Ireland at the time and needed more HDMI ports and liked the all glass design.

So, I read this thread with great interest. I never really thought that the set lacked in black since I came from a m87 Samsung LCD from 2007.


I was hesitant to try this as I really was out of my depth. I was feeling sick to my stomach as I started to remove the back cover.

1. I was scared I would electrocute myself

2. Mess the tv up with my tinkering.

I just couldn't resist getting deeper blacks just by tweaking one little pot. All I ever was going to do was the set_up as I wasn't confident I would be able to put the pots back if I messed up.

Now, it took me around three hours because I had to do this myself. My wife was going to stand in front of the tv but my 15 month old decided that he was going to wake up eary. From his nap.

It also took me longer than I thought it would.

Set_up on my set was at 10 o'clock turning it clockwise to its stop produced many pix misfires on all my inputs.

Set_dn was at around 11 and turning it clockwise even a little produced misfires, so I left it at its default.

Vy was just under 12 o'clock turning it even a little also caused problems so left it at stock.

In the end I set set_up to 3 o'clock.

Every input had it's tolerances.

Sky+HD 1080i@50Hz had the largest headroom.

PS3 1080p@24Hz was second and the least tolerant was my Apple tv2 720p@60Hz.

Every time I thought I had it set I had to dial it back because of the Apple tv.

To be honest though I didnt notice any difference from full clockwise to where I have it in terms of the black level to my eye, of course I have no way of measuring the result but it looks the same to me anyway.

I did notice the glow in black fade as I dial set_up clockwise from its default, it was like a dimmer switch for black

I had contrast set to 80 before I did the tweek now I set it to 75.

I'm glad I did the because there is a difference but it was not without it's problems. I've noticed today that there are some pixel misfires(?) from black to a lighter scene, or in the menus on a no signal screen.

It's a few red pixels that take a few seconds to go away and sometimes they are blue or green or black, just a scattering of a few random pixels.

I can't see his from my normal viewing distance of around 8-9 feet.

No problems with a cold start so I'm going to leave it as is.

haha my 7 month old son is beginning to crawl and I did not dare to open the tv unless he's sleeping or mommy's watching him. I'd probably open the tv up every day if he weren't close by :P. My 50pk550 definitely has more pop and contrast after the tweak. I just wish I can spend more time to tinker with it in the dark so I can go from about 0.02 to 0.01 ftL. I think i just need to get set_up from 12 o'clock to the 1 o'clock position.

I made measurements before the tweak, but it was only the 0 IRE window. Before the tweak the 0 IRE window was about 0.01 ftL, but after the tweak the spyder2 just didn't detect any light. This is the first time i measured the area outside the IRE windows. I guess the black level was previously around 0.035 ftL before the tweak.

There where not increase on mll when I had the first tweak from the german site but I was trying to go farther to get more headroom for the set_up by using the vs boost like turrican did but after two days enjoin those deep blacks
the tv increased the black levels by itself not by much but did increase.next step is to set everything back to normal position I marked all the pots with a black market juts in case I want to go back to original position.will report later any change.

Thats is going to be my next procedure to set everything back to factory thanks anyways just want to let people know that if you do the vs boost to get more headroom for set_up like turrican did you are going to have the best blacks after a few days then the control board is going to try to stabilized the set resulting in a increase in black levels.Is better not to increase voltages on the vs pot from the power board because the control board is going to try to stabilized the panel, better stay away from tweaking the vs pot.save your time and dont touch the vs pot

I just did a few tests on my 60PK550 comparing MLL with 24hz output on/off via the PS3. All measurements taken with a D3, Chromapure and AVS disc.

24hz Output On
on/off .018 ftl, 39.038 ftl
simultaneous .020 ftl, 25.385 ftl

24hz Output off
on/off .012 ftl, 40.201 ftl
simultaneous .014 ftl, 27.449 ftl

Also note the differences in gray scale/gamma on the attached calibration report. Pre was with 24hz output off, and post was with 24hz output on. The original quickie calibration was done to a gamma of 2.22.

 

CalibrationSummaryDetailed.pdf 127.1923828125k . file

Someone earlier in the thread mentioned black levels looking washed out on 360's Netflix video versus that of the PS3's (I can't remember who it was, perhaps rpauls or rob80b). This is a known issue with the new metro dashboard on the XBOX 360. It seems to only have an effect on video, be it Netflix or the stuff in the Zune marketplace. Apparently, the 360 is sending video levels (16-235) but is contained within a PC level (0-255) signal.

The short term solution is to change your 360's reference levels to expanded for video, then change it back to standard for games. There has been no word from Microsoft as to even acknowledge this issue, let alone the other MAJOR issue where certain 1080p video is scaled down to 720p then upscaled back to 1080p by the console.

Just wanted to clear that up.

yes it is higher than the set-up prior to the vs boost.Im not sure if turrican really trick the control board by doing all that..he needs to report on that again.

I did mine in the dark with only the bias light on. What I meant was that I didn't really notice a difference in black level from set_up at full clockwise to where I finally settled on. I did notice a large difference from its default to my final setting .

I'm really happy with the final result and can put up with the odd misfire as I can't see it from my viewing position.

As far as IR ad line bleed go I have no more and no less than before.

IR on my set is pretty instant but it goes away almost as fast as it appears and isn't a distraction in normal viewing.

Well last night around midnight I was fiddling with the tv again, and I was able to get to about 0.01 ftL with set_up at 12:30 position(full clockwise is at 3 o'clock). However, I was greedy and wanted to move set_up a microamount clockwise. Poof!!!!! the board made a sparkwhen the screwdriver slipped into the board, looked at my tv and there were red and globs of blackness. I thought I had fried the tv. Recollected myself and played around with the other pots especially set_dn and turned it all the way counterclockwise and the black glob that covered half the screen slowly disappeared. Then adjusted other pots to take out some vagrant green and red pixels and now I have a 99% good picture with occasional misfiring on the left bottom corner for near black material (IRE 5). Hence, a word of advice from someone who messed up. Next time if when i change the y sustain board (ebay about $35), I'll use a plastic head or insulated phillips head screwdriver for pots tweak. Nevertheless, my wife is probably not going to let me take the tv off the wall again. Measured MLL this morning its actually at 0.014 ftL now. Last night it was 0.02 ftL before I retweaked.

Dear forum members could you make a quick check of the serial # on lg 50pk550 ysus board? Is it this Part # EBR62294201 and substitute number EAX61326302? Thanks

Looks like the drawback with a shot set_up pot is IR. I'm getting alot more image retention now so I might have to change the ysus board. There is also a slight buzz, so I'll probably need to change out the ysus board. Who knows I might get even better picture quality, because with set_up fully clockwise the letterbox black bars are bezel black.

Thanks, I'm alive and well. The tv is almost back to normal, but the set_up is shot. Had to tweak the other 6 pots just to make up for the non functioning set_up pot. I turned set_up fully clockwise or counterwise and there is absolutely no change to the picture. Theoretically i can take the board apart and try to replace the bad part using a multimeter to detect the shorted electrical component. Nevertheless, for $35 on ebay i can probably fix the problem for relatively cheap and safer.

I had alot of equipment around, a spyder 2 with laptop, multimeter, and working in the dark late at night (bedtime). Not a safe scenario. Never thought I'd slip the screwdriver, but anything can happen. Need some mistake proof equipment like a plastic head phillips screwdriver. The problem is i was getting too comfortable with the tweak (fourth or fifth time). I knew I needed to stop opening the panel and call it quits, but that curiosity and greediness to squeeze the last drop got me.

Second thought, I might just let it be and just enjoy the picture. The IR is more prevalent, but minutes of viewing eliminates it. I was lucky to live to tell the story, so I should just take my marbles and run with it.

I have the same panel and have observed about the same white point and black point dependencies on refresh rate as you posted. The TV definitely performs better when not fed a 24fps input.

I have spent many hours painstakingly performing the full 20 point calibration on this at 60Hz only to find it not quite perfect at 24fps. Also, the CR is so much better at 60 (both ASCII and on/off) as you found.

My choice, just run it in 60Hz mode for all inputs.

Thanks for sharing your results. Will you try the pot tweak? I dropped my MLL from around .030 down to .007 at 60Hz, and my white point is still at a blazing 50 ftL for my daytime setting.

I actually performed the pot tweak early on. I am trying to borrow an oscilloscope to dial it in. I will also use my multimeter to adjust the other pots to spec at that time. I do not plan on doing a 60hz calibration until after that.

There is something wrong here the LVDS-cable is conencted from the MAIN BOARD to the CONTROL BOARD not to the Y-SUS BOARD and he write to remove the LVDS-CABLE from the Y-SUS BOARD.No wonder I was trying this with no success he needs to explain this better.Does he mean the ribbon cable connected from the CONTROL BOARD to the Y-SUS BOARD?