LG Plasma Panel tweaks for better blacks. - Page 18

Mine's been stable at .007 for 6 days so far.

Mine has been stable for several weeks. no deleterious effects that I can discern.

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. Maybe someone should figure a smart way to drill holes in the cover to get at the pods.

I'll take deep blacks with a two minute warm up anytime.

Mine has been stable for 2 months easy. No noticeable rise, and if there ever is, it wont be there for long.

I agree. We should at least have access to the set_up/set_down adjustments through a service menu. I am frankly astonished at how significant their impact on MLL is. I keep thinking there must be some negative side to all this, but so far I can not find it. Why would the factory not optimize these before shipping? Maybe the required setting changes as the set ages and they pick a conservative starting point at the factory? If so, I am ready with my screwdriver ;-)

I was very tempted to drill two holes in the back, and would have done it for sure if I wasn't wall mounted.

The tweak work also with my 50ps8000 (like ps80).
I had problem with the black level of the tv (0,22 cd/m2) and now it finally return at 0,06cd/mc2

perfect!

Hey guys,

gonna open up my new 50PZ950s for pot tweak tomorrow. I read there are tons of screws to remove to open the back. Are those screws all the same length etc. or should I note which screw belongs where?

thx

boba

I can speak for the pk550 which does have a few different sizes but the locations are obvious. I would make note of the odd ones, that's all.

hey rob,

thx for the quick answer and links. Well, I posted this in the other thread, that I kinda doubt all this hype about "breakin" and stuff. This is not my first plasma and I never experienced any issues with running my sets at "full throttle" from day one.
Anyway, what exacty would you mean with "phosphors would have a chance to settle". How would I know when they did so? Or does this again mean ... just waiting 200 hours and running the set at max 50 contrast/brightness?

thx

boba

Rob,
Thanks for the link. I have the 60PZ950, which isn't listed, nor is the 60PK950. If I wanted to double check voltages with a meter, where can I find the proper specs (or a safe range) for my model. I've read most of the thread so I know the manuals say one thing and the sticker may say something else, neither of which may be best for achieving optimum black.

thanks,
Edward

I've been following this thread for a few weeks and honestly quite impressed at the progress everyone has made! About two weeks ago (unknown to my parents at the time ) I removed the back of the 60PX950 and adjusted set-up just about fully clockwise. WOW. It certainly did make quite a difference. I also adjusted va and vy (don't remember which way) but in any case, it didn't make much of a difference. I also moved set-down a bit, and that made a small but noticeable difference.

Fast forward a week- as people know, these sets are supposed to follow certain voltage requirements as indicated on the set. I took out the multimeter and adjusted everything (VS, VA, VSX, -VY, VZB adjustments) in accordance to the label within .1 volts (for some I was able to get spot on). Some were off by a couple volts to begin with, but I forget if that was because I had made random adjustments to them earlier). After vacation I am going to borrow an oscilloscope from school and see how accurately i can adjust set-up and set-down according to the manual.

Questions:

• For people making adjustments (other than set-up) fully clockwise/counter clockwise, how difference is the resulting voltage than the voltage indicated on the panel sticker?

• Has anyone tried adjusting set-up and down with an oscilloscope and matched it with the waveform as indicated in the manual? If so, is there a difference in position of the knob than if you had simply turned set-up as far clockwise until misfires appeared? (if that question made any sense)

• Are your voltages different to begin with than what is indicated on the sticker?

• For those who have made tweaks and seem to have improved black levels without misfires, how do the voltages compare to the sticker? If they are close to spot on, this likely means that these sets had potential to have stable and dark blacks but LG didn't spend enough time ensuring the sets were properly adjusted.

For those interested in this tweak, I definitely recommend performing it. First adjust VS, VA, VSX, -VY, and VZB according to the label on the tv, adjust set-up clockwise as high as possible without getting misfires, and adjust set-down counterclockwise until misfires occur. Also, make sure the TV is warmed up for about 15 minutes, and remember to go back at the end and test all the voltages, because sometimes adjusting one will offset another. However, be aware we are dealing with potentially lethal voltages, so be VERY careful not to touch anything else besides the contacts exactly as shown in the "Quick Reference Alignment Hand Book." Also if possible, use an anti-static or plastic screwdriver to make adjustments.

That thread describes the "reset" as it applies to black level and priming particles (free electrons) only, as this is what that thread was about. To simplify things I left out how "reset" applies to pixel control. Unfortunately when you adjust the reset pulse you are adjusting the pixel control aspect as well as the priming particles. I'll edit that post to include this info as now both LG and Pioneer reset tweakers have arrived

Control aspect
Ideally after reset every pixel should have an equally low level of wall charge heading into the address period. If the reset pulse is too strong or too weak the wall charge is not equalized properly and the reset discharge and subsequent address discharges become unstable and result in uncontrolled pixels

Priming Particle aspect
Ideally the reset discharge is weak and produces free electrons that assist the subsequent address discharges making them happen faster and with high probability. If the reset becomes too weak and unstable it may not produce the desired amount of priming particles and this would result in pixel lag (after applying a voltage it takes longer for discharge to occur).

This does not even cover the concept of voltage margin and how it relates to the reset pulse and pixel control.

LG has a good paper that describes trying to produce a panel with no reset pulse and how difficult it is. They managed to make a prototype but it had too many misfiring pixels to be a product it seems.
LG panel without RESET

I used a scope and a meter during my tweaking. You can find several of my posts searching back in this thread. In my case, all the voltages (other than set_up/dn) were very near the values listed on the sticker, indicating to me that LG spent a good amount of time tuning each set before shipping. They were all off by less than 1 volt. I readjusted them to near exact.

Set_up and set_down was a different story. In my case, the waveform showed the set_up pulse height too high and the set_dn ramp width too short, both contributing to higher MLL. I adjusted both to specs and achieved very good blacks. In my case, even with set_up fully clockwise I was still a little higher than the specified voltage for the waveform, so even when fully clockwise I saw no misfires of course. Why LG apparently tuned the other 5 voltages and not set_up/dn is a mystery to me.

I was able to push set_down a little past the spec and achieved even darker blacks before misfires began to occur. A little past the spec point the waveform ramp eventually hits a wall and starts to lift off the voltage floor. It is shortly after this that misfires occur, so I'm guessing it is important to have the ramp stay on or near the floor. I left set_down adjusted so the ramp was as wide as possible before it started lifting. Probably could have pushed a bit more, but it was already so dark I figured it wasn't worth the chance I'd have to take the tv of the wall again.

Thanks. But did you mean set-down clockwise? From what I understand, clockwise lowers the MLL, while counterclockwise raises it.

I have not had to open my pz950 for a while I just don't think I can get blacks any deeper and more importantly, don't feel I need to since I feel they're black as they can get. No meters or equip, just eyeballed.

Followed these instructions exactly...

"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 movie scenes

(I was able to turn Set_Up full throttle with no issues)

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."

...and with harvro's suggestion on the VS and VZB (both only moved a hair on my set as had negatives if too much either way) and never touched VSC.

Still curious though as far as what impact did the va and VY have on turning full throttle? Do they take credit as to why I have NO issues like misfires, pixels, or anything whatsoever?

I am sure some of the real tekkie guys here may tell me that there is some kind of pic anomaly that I am oblivious to.

Oh! NBA is back and looking so killer on my set! I've said it beforehand I'll say it again...u guys here ROCK!

I knew it was going to knock your socks off!

Now that I have a multimeter, I'm going to adjust voltages and do the tv again one more time.

Now that I've heard LG is making an 84" Ultra resolution 3D tv, and a 55" OLED, I may just need to upgrade again next year.

Initially my 50pk550 had some random red pixels on a white screen with set_up not even full clockwise (1 o'clock), Va full clock, and Vy full counter. Then I reopened the panel and dialed back Vy a slight notch clockwise, and then I went full clockwise set_up. Now, I've got a clean screen even on start up, but I think the black bars are grey in a pitch dark room. Nevertheless, actors black clothes are really dark so I guess that's the best the tv can do :P. How black is 0.008 ftl? The black level is definitely better during the day, but I like watching movies in pitch dark. Some ppl posted tv pictures with dark black bars, is that in a pitch dark room?