LG Plasma Panel tweaks for better blacks. - Page 15 - AVS Forum
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post #421 of 1409 Old 12-14-2011, 03:44 PM - Thread Starter
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For those who hadn’t checked out the German HiFi-forum.

http://www.hifi-forum.de/viewthread-141-2177.html

Googles English translation.

http://translate.google.com/translat...-141-2177.html

created: 10 Feb 2011, 13:07

“Poti tuning of the LG-PK series - the way to correct ...”

“Here I wanted to, because there are no separate thread for this, one just to make the tuning potentiometer, the LG-PK to treat screens ...!

Here the guidance of Marc Wessel:
-------------------------------------------------- --------
Now that I've continued experimenting with multi-meter, I can tell you that it follows at least in my Panel->

First Vs. leave it where it is (the ten to 12 hours I could have saved me)

Second Va clockwise until it stops

Third VZB eighth turn clockwise

4th VSC first turn counterclockwise until it stops and then a quarter turn clockwise

5th Vy until it stops turning counterclockwise

6th Pick a movie scene that is full-frame (ie without cinemascope, zoom in doubt easy!) And a cloudy sky at the top of the screen and has (or a snowy landscape.

Turn SET_Dn so long in a clockwise direction until you get strange-looking beige vertically oriented noise pattern.

Then you go counter-clockwise back to exactly the point, these noise bars disappear on the back!

7th SET_UP turn clockwise until you get blue, red and / or green pixel misfire.

Turn counter-clockwise back a touch delete the faulty pixel with the ColorWasher and see then whether it comes back to pixel misfire - if yes, run by the same procedure again.

Repeat this until you get no more error pixel.


Actually done, but you can still try further:

8th Now you can still use Vy for fine adjustment and it goes like this:

Turn SET_UP far so clockwise, until you get back but light and small backfires.

Vy then turn in one 16teldrehung Uhrzeigerinn delete the faulty pixel with the ColorWasher and see if the misfire occur no more. If it does, another six-tenths of a turn clockwise with Vy.

If at the end instead re-appear vertically oriented beige bars of interference, it is not worth it to give up potential for Set_Dn and instead simply Vy You turn back counter-clockwise until it stops.

Done. Watch the best the next day as normal remote, to ensure that indeed no artifacts appear before you screw on the TV again.
------------------------------------------------

Here are the explanations of the individual pots lekabel:
------------------------------------------------
Vs = Voltage for sustain)
VS supplies the panel's horizontal Electrodes.
Drives the display panel horizontal grid (SBS Board)


(Va = Voltage for Address)
VA supplies the panel's Vertical Electrodes (routed to the Left X-Board)
Primarily responsible for Display Panel Vertical Grid (X boards, TCPs).

VY-sets the negative excursion of reset in the Drive Waveform

VSC sets the amplitude of the waveform complex.

VZB - The Z-SUS (in combination with the Y-SUS) generates a
SUSTAIN and to ERASE PULSE signal for generating
Z-SUS SUSTAIN Waveform and DISCHARGE in the panel.


SET_UP fundamental voltage / trigger edge (White)

SET_Dn fundamental voltage / trigger edge (Black)

At last setting and correct the Vs, Va, and VSC-Vy - The sticker on the panel provides the correct values - you can adjust without fear SET_UP / SET_Dn. For best results, provides an oscilloscope. But the results are manually niche outstanding.

VZB should be corrected if (apart from Dirty Screen problem for the film because 760/950er) the so-called picture abnormal phenomenon occurs.
= abnormal picture Dirty Screen?

Robert
Toronto, Ontario
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post #422 of 1409 Old 12-15-2011, 06:25 AM
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Thx the last two posts are very informative, and kind of explains the problems I saw on my first potituning attempt :P. Hopefully your solutions help me next time I take the tv down, and hopefully last.
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post #423 of 1409 Old 12-15-2011, 02:48 PM
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Now I know why the german site didn't keep writing about the same thing,They just did the pot tweak method couple of pages and that's it,People get confused every time we post here, It mess all the original info.
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post #424 of 1409 Old 12-15-2011, 03:28 PM
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Quote:
Originally Posted by losservatore View Post

Now I know why the german site didn't keep writing about the same thing,They just did the pot tweak method couple of pages and that's it,People get confused every time we post here, It mess all the original info.

I wasnt necessarily confused. Ok well I was REALLY confused about all the techno-lingo. In retrospect, I should of just listened to my gut and left well alone. However, after shi-tting my pants after I originally ROYALLY messed up my TV, I got things tuned and am glad I messed with it.
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post #425 of 1409 Old 12-20-2011, 07:44 AM
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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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post #426 of 1409 Old 12-20-2011, 08:03 AM
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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

So break out a multimeter and match up Set_Up and Set_Dn? I just may
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post #427 of 1409 Old 12-20-2011, 08:27 AM
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Quote:
Originally Posted by bhazard View Post

So break out a multimeter and match up Set_Up and Set_Dn? I just may

No, you need an oscilloscope to match set up and set down because you need to measure only a portion of the waveform. This can't be done with a multimeter.
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post #428 of 1409 Old 12-20-2011, 11:13 AM
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Quote:
Originally Posted by rpauls View Post

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)

Thanks for your report. Very helpful. Just one question, in order to get Set_Down to 140us, did you need to go clockwise or counterclockwise?
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post #429 of 1409 Old 12-20-2011, 11:39 AM
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Quote:
Originally Posted by Voz View Post

Thanks for your report. Very helpful. Just one question, in order to get Set_Down to 140us, did you need to go clockwise or counterclockwise?

I forget. I did mark the original position. When I get home tonight I'll take a look.

I am also going to go back and remeasure all the other voltages and see if anything changed. I am curious as to why I could not achieve 280V exactly with the set_up measurement. Even at full clockwise I could only get down to 290. Maybe one of the other voltages is off now that set_up has been maxed? Just a thought. The one with the most error I think was Vs (201.3 instead of 202V). Can't imagine this makes much difference. We shall see.

Round 2 tonight!
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post #430 of 1409 Old 12-20-2011, 11:44 AM - Thread Starter
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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.

Rich

Thanks rpauls,

Excellent news,

("but I could get set down to exactly 140us, and both ramps in the waveform looked just like the picture.")


I was hoping someone would actually use a scope as I intuitively mentioned using one at the start of the thread.

Robert
Toronto, Ontario
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post #431 of 1409 Old 12-20-2011, 11:48 AM - Thread Starter
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Quote:
Originally Posted by rpauls View Post

I forget. I did mark the original position. When I get home tonight I'll take a look.

I am also going to go back and remeasure all the other voltages and see if anything changed. I am curious as to why I could not achieve 280V exactly with the set_up measurement. Even at full clockwise I could only get down to 290. Maybe one of the other voltages is off now that set_up has been maxed? Just a thought. The one with the most error I think was Vs (201.3 instead of 202V). Can't imagine this makes much difference. We shall see.

Round 2 tonight!

Turrican mentioned the the other pots could give you more headroom for the Set_up and Set_dn, and there you could use the multimeter.

Robert
Toronto, Ontario
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post #432 of 1409 Old 12-20-2011, 11:54 AM
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Originally Posted by rob80b View Post

Thanks rpauls,

Excellent news, I was hoping someone would actually use a scope as I intuitively mentioned using one at the start of the thread.

Thanks Rob, It was your post that made it all possible. All I did was follow the directions in the LG teaching manual exactly. Thanks for providing the link to these documents!

It is so easy to do with a scope and multimeter, and you can nail it perfectly with no risk of introducing artifacts. I would recommend to anybody who can, to borrow a scope if necessary (and a friend who knows how to use it) and use this method. At the very least set the other 5 voltages to the levels specified on your label. This only requires a multimeter, which is 15.00 at Sears.

I think it is a bad idea to tweak any of these voltages by eye, but if you insist, and have no meter or scope, I would only turn set_up, and leave the rest alone.
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post #433 of 1409 Old 12-20-2011, 12:17 PM
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Quote:
Originally Posted by rpauls View Post

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.

Btw, I compared the waveforms for your 60R1 panel and my 50R1 panel (in the LG docs) and they look quite different. And for the 50R1 Set-up should be at 320V and Set-Dn at 180uSec.

I need to get that oscilloscope...
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post #434 of 1409 Old 12-20-2011, 02:24 PM - Thread Starter
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Quote:
Originally Posted by rpauls View Post

It is so easy to do with a scope and multimeter, and you can nail it perfectly with no risk of introducing artifacts. I would recommend to anybody who can, to borrow a scope if necessary (and a friend who knows how to use it) and use this method.


Now I just have to remember how to use it. (Thought the screen shot was appropriate for us posters)

This my most recent scope all the others are antique tube based, hopefully it'll do.

Robert
Toronto, Ontario
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post #435 of 1409 Old 12-20-2011, 02:39 PM
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Quote:
Originally Posted by rob80b View Post

Now I just have to remember how to use it. (Thought the screen shot was appropriate for us posters)

This my most recent scope all the others are antique tube based, hopefully it'll do.

That scope will be fine if you can get a 10X probe. I see the max input is 20V/div, and the signal you need to measure is about 580 volts p-p so it's not going to fit on that screen with a 1X probe.
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post #436 of 1409 Old 12-20-2011, 03:12 PM - Thread Starter
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Quote:
Originally Posted by rpauls View Post

That scope will be fine if you can get a 10X probe. I see the max input is 20V/div, and the signal you need to measure is about 580 volts p-p so it's not going to fit on that screen with a 1X probe.

Hi rpauls

Are you sure? I believe the max voltage to the Y-Sustain board is 18v +-., the offset being about 5.25v. and the maximum wattage is 450watts.

Robert
Toronto, Ontario
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post #437 of 1409 Old 12-20-2011, 03:17 PM - Thread Starter
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Quote:
Originally Posted by rpauls View Post

That scope will be fine if you can get a 10X probe. I see the max input is 20V/div, and the signal you need to measure is about 580 volts p-p so it's not going to fit on that screen with a 1X probe.

Ok I see what what you're looking at, although that's the full voltage applied to the panel and not what actually drives the waveform, I believe.

Robert
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post #438 of 1409 Old 12-20-2011, 03:26 PM
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Quote:
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Ok I see what what you're looking at, although that's the full voltage applied to the panel and not what actually drives the waveform, I believe.

Yes, this is the signal you need to display in order to make the adjustments. On the next few pages after the page you posted you should see the portions of the waveform that you will be zooming in on (It is the region in the red rectangle in the page above). As you can see, this waveform has a p-p voltage of over 500V and your scope needs to accept this. You hve to sync on the two big pulses. You at least need to be able to display the entire set_up region of the waveform on the screen in order to measure it (top half of the second big pulse in the pair). In my case it needed to be 280V. What is the spec for your panel?
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post #439 of 1409 Old 12-20-2011, 04:07 PM - Thread Starter
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Quote:
Originally Posted by rpauls View Post

Yes, this is the signal you need to display in order to make the adjustments. On the next few pages after the page you posted you should see the portions of the waveform that you will be zooming in on (It is the region in the red rectangle in the page above). As you can see, this waveform has a p-p voltage of over 500V and your scope needs to accept this. You hve to sync on the two big pulses. You at least need to be able to display the entire set_up region of the waveform on the screen in order to measure it (top half of the second big pulse in the pair). In my case it needed to be 280V. What is the spec for your panel?

Thanks rpaul.

Mine is the PX950 as shown so I believe it should be 502Vp/p.

Robert
Toronto, Ontario
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post #440 of 1409 Old 12-20-2011, 04:14 PM - Thread Starter
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For those wondering what we are referring to, it should be in the service manual for each panel.


Quote:
Originally Posted by rpauls View Post

Yes, this is the signal you need to display in order to make the adjustments. On the next few pages after the page you posted you should see the portions of the waveform that you will be zooming in on (It is the region in the red rectangle in the page above). As you can see, this waveform has a p-p voltage of over 500V and your scope needs to accept this. You hve to sync on the two big pulses. You at least need to be able to display the entire set_up region of the waveform on the screen in order to measure it (top half of the second big pulse in the pair). In my case it needed to be 280V. What is the spec for your panel?


Robert
Toronto, Ontario
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post #441 of 1409 Old 12-21-2011, 07:04 AM
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I've watched my tweaked 50PK550 (see post #360 above) for 2 weeks now. A few remarks:

No major issues or changes in the now-excellent PQ. The tweak seems stable. Black level is still extremely good. As noted I do have some pixel misfires but these I continue to find completely tolerable and very hard to spot from my view distance; I'm happy to have traded these off for hugely improved mll.

About the misfires:
-- At switch-on, esp. when the room is cold, I sometimes suddenly see a lot of misfires ... BUT weirdly, these disappear almost immediately (20 seconds or less).
-- Very very occasionally during ordinary viewing I do see some misfires. This happens less often than once per movie. When the screen is mostly green, say, I will sometimes (not always) notice a few trivial specks.
-- I think there may be more misfires in 60Hz than 72Hz but the difference is subtle.
-- Using colour bar patterns, I verified the misfires were random, i.e. not the same pixels are misfiring every time the same image is refreshed. So I hope I won't damage the cells by consistently volt-starving them. So far so good.

About the black level rise a few others have reported:
I can't check the actual hrs used on my 20-month old TV (have no LG service or Harmony remote so can't get into the service menu), but I haven't noticed any permanent black level rise (in a light-controlled bias-lit room). On 3 or 4 occasions since I bought it I've suspected it was looking grayer; each time it went back to normal within a day or two. I speculate some routine internal adjustment caused this or it could have been a temporary glitch.

Above image retention:
My IR hasn't increased at all after the tweak, if anything it seems to be less noticeable now. Go figure.

"... 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
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post #442 of 1409 Old 12-21-2011, 09:20 AM
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Originally Posted by walt73 View Post

I've watched my tweaked 50PK550 (see post #360 above) for 2 weeks now. A few remarks:

No major issues or changes in the now-excellent PQ. The tweak seems stable. Black level is still extremely good. As noted I do have some pixel misfires but these I continue to find completely tolerable and very hard to spot from my view distance; I'm happy to have traded these off for hugely improved mll.

About the misfires:
-- At switch-on, esp. when the room is cold, I sometimes suddenly see a lot of misfires ... BUT weirdly, these disappear almost immediately (20 seconds or less).
-- Very very occasionally during ordinary viewing I do see some misfires. This happens less often than once per movie. When the screen is mostly green, say, I will sometimes (not always) notice a few trivial specks.
-- I think there may be more misfires in 60Hz than 72Hz but the difference is subtle.

Walt,
Did you measure the voltages Vs, Va, Vy, VSC, VZB with a meter or just tweak them by eye? The misfires should go away if you carefully set these to the values on the panel sticker. I have never seen a pixel misfire and my MLL is now down to .008 simply by following the steps in the manual.

All of my voltages were very close to begin with, so it seems to me someone took very good care to set theses correctly at the factory. I noticed that the slightest turn of these pots causes the voltages to swing dramatically, so they obviously took the time to adjust each unit by hand. A tribute to LG quality control. The only adjustments off on mine were set_up and set_down. All of the MLL improvement came from set_up adjustments in my case.
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post #443 of 1409 Old 12-21-2011, 09:28 AM
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Quote:
Originally Posted by Voz View Post

Thanks for your report. Very helpful. Just one question, in order to get Set_Down to 140us, did you need to go clockwise or counterclockwise?

I checked last night, and to increase the set_down ramp width from 125us to 140us required a very slight turn clockwise.

In my case, here are my approximate before and after settings for up/down in terms of o'clock reference:

Set_UP
original = 12:00, final=3:00 (max clockwise)
This change reduced Set_up pulse height from 350V to 285V (target = 280 for my panel).

Set_Down
Original = 3:00, final = 3:30 (very slight turn clockwise)
This change increased Set_down ramp width from 125us to 140us (target = 140 for my panel).

The above two adjustments reduced my measured MLL from .036 FtL to .008 FtL. I believe all (or at least most) of the improvement was do to the Set_up adjustment.


Rich
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post #444 of 1409 Old 12-21-2011, 09:42 AM
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Quote:
Originally Posted by rpauls View Post

Walt,
Did you measure the voltages Vs, Va, Vy, VSC, VZB with a meter or just tweak them by eye? The misfires should go away if you carefully set these to the values on the panel sticker. I have never seen a pixel misfire and my MLL is now down to .008 simply by following the steps in the manual.

All of my voltages were very close to begin with, so it seems to me someone took very good care to set theses correctly at the factory. I noticed that the slightest turn of these pots causes the voltages to swing dramatically, so they obviously took the time to adjust each unit by hand. A tribute to LG quality control. The only adjustments off on mine were set_up and set_down. All of the MLL improvement came from set_up adjustments in my case.

Eyeballed. I have no volt meter or light meter either, so the only way I can be absolutely sure I won't reduce misfires at the cost of higher mll is to push it past the misfire point (setting to my own personal tolerance). (I can see the misfires directly but can't directly see a sufficiently subtle mll bump.)

On mine I ultimately adjusted Vy one clock position to the left; Set-Up moved quite a bit, to 5 o'clock from 1'oclock default, didn't touch anything else.

"... 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
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post #445 of 1409 Old 12-21-2011, 10:01 AM
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Thanks rpaul.

Mine is the PX950 as shown so I believe it should be 502Vp/p.

Rob,
It is interesting how different the instructions are for your PX950 compared to my PK540. From the plots you posted, it appears your waveform has 3 large pulses after blanking and the measurements are taken on the first one. Mine has only 2 large pulses, and the measurements are taken on the second one. Apparently the design is quite different between these two.
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post #446 of 1409 Old 12-21-2011, 10:02 AM
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I reopened the 50pk550 last weekend and was able to go max clockwise for set_up after tweaking Vy back to the original position. However, I actually feel like the black level might not be as good as when I had it with Va full clockwise and Vy full counter and Set_up slightly clockwise. My Spyder 2 is not accurate measuring black levels so I just assess by eye. It was dark gray in dark room before, but now its kind of bright gray in pitch dark room. I tried to use a cheap $5 multimeter from Harbor Freight, but it doesn't seem to be accurate and sometimes don't read at all. Second thought I might have not used it correctly or will need to pick up the Sears $12 multimeter that is onsale. Nice job with the scope, too bad I don't have access to a scope. This pots tweaking is looking like its going to keep going on, but it does look like it got a little darker than stock.
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post #447 of 1409 Old 12-21-2011, 10:18 AM
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I reopened the 50pk550 last weekend and was able to go max clockwise for set_up after tweaking Vy back to the original position. However, I actually feel like the black level might not be as good as when I had it with Va full clockwise and Vy full counter and Set_up slightly clockwise. My Spyder 2 is not accurate measuring black levels so I just assess by eye. It was dark gray in dark room before, but now its kind of bright gray in pitch dark room. I tried to use a cheap $5 multimeter from Harbor Freight, but it doesn't seem to be accurate and sometimes don't read at all. Might need to pick up the Sears $15 multimeter that was onsale yesterday. Nice job with the scope, too bad I no access to a scope.

Yes, I saw that sale. It's a great buy for 15.00. Go for it.

I have no doubt that one could achieve even lower black levels by tweaking of those other voltages (after all, it is really black when it's off), but my concern is that we don't really know what other aspects of picture quality we might be affecting. We could be trading some sort of picture linearity or dynamic range for the sake of deeper blacks. Without a better understanding of how these panels work I did not feel comfortable adjusting away from the values on the sticker, but maybe one day I will learn more and give it a try. For now, I am as happy as can be. .008 is a great MLL, and I after calibration I can still see levels 17 and 18 in the test patterns, so I know there is no black crush either.
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post #448 of 1409 Old 12-21-2011, 10:49 AM - Thread Starter
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Rob,
It is interesting how different the instructions are for your PX950 compared to my PK540. From the plots you posted, it appears your waveform has 3 large pulses after blanking and the measurements are taken on the first one. Mine has only 2 large pulses, and the measurements are taken on the second one. Apparently the design is quite different between these two.

Hi Rich

The PX is not listed but I'm sure it's the same 50R1 panel that is used in 50PK950, 50PK750, 50PK560, 50PK550, 50PK540, 50PK250, so the procedure would be the same. For the flagship models there is probably a more judicious selection of the actual panel and LG hopefully just took more effort in the factory adjustments.

50R1 Plasma Alignment Handbook
http://136.166.4.200/contents/Displa...-HAND-BOOK.pdf

Robert
Toronto, Ontario
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post #449 of 1409 Old 12-21-2011, 11:15 AM
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I wonder if people are doing the pots adjustment in the dark to see changes? I seem to be satisfied when tweaking during the daytime, but dissappointed once the room is pitch black at night. Thanks
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post #450 of 1409 Old 12-21-2011, 07:28 PM
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I wonder if people are doing the pots adjustment in the dark to see changes? I seem to be satisfied when tweaking during the daytime, but dissappointed once the room is pitch black at night. Thanks

Thats what I did. And my room is almost completely light controlled.
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