Panasonic black level shift fix!

[hardc0re]

Hi people,

I'm using a Panasonic 42PX500 (Asian version of 42" PV500). I've experienced the "black level shift" problem that many of the PX500/PHD8UK owners have. There was a fix issued for the commercial version 42PHD8UK, but that fix is not applicable for the consumer version (PX500/PV500).

I've found a way to fix the black level on the consumer versions! This is what I did:

In the service menu, you have to lower the "ALL DRIVE" setting significantly, and then increase the Contrast in the normal menus to compensate.

Factory/default settings (HDMI input):
The original/factory "ALL DRIVE" setting was 252.
I was using a Contrast in the standard menu of 0 (lowest setting) because otherwise, the screen was just too bright.
With these default values, I got black level shifting in high-contrast (lots of white) scenes.

The values that got rid of black level shifting were:
I set the ALL DRIVE to 170.
I increased the Contrast in the normal menu to 50 (mid setting), and change it between 30-50 depending on the time of the day.

NO MORE BLACK LEVEL SHIFTS! :)

My theory is this - the black level shift is actually a function of the TV trying to lower the image contrast. I think the Panasonic factory default "all-drive" setting is much too high, and as a result under normal viewing one has to lower the Contast setting to very low levels (near minimum).

Somehow the very low "Contrast" setting causes the TV to compensate by shifting the black level when there are very bright images.

Lowering the all-drive enables one to use a higher "Contrast" setting, thus eliminating the black level shifting.

[optivity]

OK, can you provide the detailed step-by-step instructions to follow in order to access and make these modifications while in the service menu?

[optivity]

bump... how about those instructions... I'd like to give them a try...

[1920x1080]

[QUOTE=hardc0re]...In the service menu, you have to lower the "ALL DRIVE" setting significantly, and then increase the Contrast in the normal menus to compensate...[/QUOTE]Where did your Brightness (black level) user control end up (compared to where you were before)?

[hardc0re]

[QUOTE=1920x1080]Where did your Brightness (black level) user control end up (compared to where you were before)?[/QUOTE]

The same, I didn't change the Brightness level. For my setup, I set Brightness at 50 (the mid setting).

[QUOTE=optivity]OK, can you provide the detailed step-by-step instructions to follow in order to access and make these modifications while in the service menu?[/QUOTE]

Sorry dude, don't have the time to write detailed guide on how to get into the SM. But the info is out there, do a search or visit one of the FAQs.

[optivity]

[QUOTE=hardc0re]Sorry dude, don't have the time to write detailed guide on how to get into the SM. But the info is out there, do a search or visit one of the FAQs.[/QUOTE]Since you already have it all figured out... why not be a pal and provide a link to your source?

[hardc0re]

[QUOTE=optivity]Since you already have it all figured out... why not be a pal and provide a link to your source?[/QUOTE]

Here ya go:
http://www.glaucobruzzi.com/plasma-faq/showthread.php?t=23

However I find that those instructions are not applicable for my model 42PV500. I use this combination to access the service menu:

[EDIT]

As always, don't mess around in the Service Menu unless you know what you're doing, or you risk damaging your set.

[Woodrow]

Service menu codes are not allowed to be posted on the open forum. Please PM the code I just deleted to AVS member BruZZi so that it will be included where it is applicable.

Thanks

[checkbit]

I was all pumped to try this but i cant find an "all drive" setting at all. I may not be in the right area of the menu. Do you have to use a different code than the one on Bruzzi's page?

[optivity]

[QUOTE=Woodrow]Service menu codes are not allowed to be posted on the open forum. Please PM the code I just deleted to AVS member BruZZi so that it will be included where it is applicable.

Thanks[/QUOTE]"hardc0re," as you can see the AVSF mod has deleted/changed your link. When you have the opportunity, please PM me with your link so I can test the service menu adjustments.

[HallertauRogue]

Just thought I'd add that one of the first things I did with my 50" 8UK was to drop the all-drive down. Its worth noting I've never seen black level shift on my panel.

[hardc0re]

Guys,

Initial testing after dropping the all-drive level was that there was still some black level shifting going on (but less).

The good news is, I think I've found another setting in the Service Menu that affects the black level shifting.

In my set (42PV500) its called "APL Mult" I guess it means "Average Picture Level Mult(iplier)?" Mine was set at 31, and could be turned down as low as 16 or as high as 63 (the menu would not allow any higher/lower settings).

I found that turning "APL Mult" down to 16 really does lower the black-level shifting, and increasing the setting to 63 increases the shifting. So I've got my "APL Mult" = 16 now and definitely see even less black level shifting (almost none! the only time i see minor shifting now is on a 50% black 50% white test image).

Worth giving it a shot!

[fasTLane]

Are you sure all these changes are not affecting the overall display quality?

[1920x1080]

I would be curious to hear how all this has affected the 100 IRE white output (both windowed and full-field).

[hardc0re]

[QUOTE=fasTLane]Are you sure all these changes are not affecting the overall display quality?[/QUOTE]

As far as I can tell, its affecting the overall display quality in a positive way. There seems to be overall better contrast now.

With the "APL Mult" adjustment I'm noticing no more black level shifting and overall better contrast & saturation.

[Shad0wz]

Strange thing with all this talk about black level shifting... Ive never seen it occur on my 50px50u .. and Ive been looking for it...

Edit.... Correction.. now I do :(

[Kevin C Brown]

Does this work for the 8uk's?

[assJack1]

[QUOTE=Shad0wz]Strange thing with all this talk about black level shifting... Ive never seen it occur on my 50px50u .. and Ive been looking for it...[/QUOTE]

I could be wrong, but I thought it was an issue only on 42" models that dealt with an external sensor being designed into the wrong location.

[RichB]

[QUOTE=hardc0re]As far as I can tell, its affecting the overall display quality in a positive way. There seems to be overall better contrast now.

With the "APL Mult" adjustment I'm noticing no more black level shifting and overall better contrast & saturation.[/QUOTE]

I have the commercial7UY. I do not think it has that menu. What menu is the APL Mult in?

-- Rich

[Kevin C Brown]

All Panasonics have it. I've seen it on the PX50, PX500, and PD50. Different sizes. CNet reviews note it on the 8uk models (that's why I asked :) ). And Home Theater Mag noted it on one of the consumer models too (can't remember the model).

[hardc0re]

[QUOTE=RichB]I have the commercial7UY. I do not think it has that menu. What menu is the APL Mult in?
-- Rich[/QUOTE]

I have the consumer PV500 model (PAL/Asian). The "APL Mult" setting is in the first service menu (Service Menu 1), somewhere after the colour adjustments (R-drive, B-drive, G-drive).

If you can find a setting somewhere in your menus that says "APL", Auto Picture Level, etc., then try to adjust that one.

After several days of usage, I can confirm that lowering the APL Mult setting has eliminated the black level shift. I'm a happy user now! :)

[assJack1]

[QUOTE=Kevin C Brown]All Panasonics have it. [/QUOTE]

All Panny's have it? People who own the 65" say that it is not there. Where is Harkness when you need him...

[rover2002]

[QUOTE=hardc0re]

After several days of usage, I can confirm that lowering the APL Mult setting has eliminated the black level shift. I'm a happy user now! :)[/QUOTE]

Have you seen eny negative effects from lowering 'Apl Mult' setting? ie , a drop in black lvl, more chance of burn-in ect?
It would be good at last to have a fix to this issue that many ppl have voiced consern over, but i remain unconvinced !
Why have Panasonic not found this simple fix and got it out to techs in the field?
Why Panasonic WHY?

[rover2002]

[QUOTE=Kevin C Brown]All Panasonics have it. [/QUOTE]

My Panasonic toaster does'ent have it, thank god!

[RichB]

[QUOTE=assJack1]All Panny's have it? People who own the 65" say that it is not there. Where is Harkness when you need him...[/QUOTE]

I have a 657UY. There is no APL Multi.
There is R,G,B Drive, R,G,B Cutoff, All Drive, All Cutoff. That's it.

Of course, I may not believe my lying eyes ;)

-- Rich

[tomboyter]

Many people over the past two years have said that the TH-50PHD7 and 8UK's do not have the "floatiing blacks" problem. Within the past couple of weeks there have been threads started by people confirming that the 50" commercial panel DOES HAVE THE BLACK SHIFT PROBLEM ! In addition, the CNET review of the 50" commercial panel lists the "floating blacks" amont the Cons for this set.

Several people have said that the "fix" won't work on the 50" panels because the menu setting for "Letter Box Mode" does not exist. Have I missed something or is this in fact the case.......the "Fix" only applies to the 42PHD8UK and the 37PDH8UK. Bruzzi's FAQ on this issue clearly states that only these two models have the service menu tweak that eliminates the problem...and by the time that it is posted there it is usually bullet proof.

I guess that this means that the PWD8UK has the floating blacks, and like the 50 does not havve the "Fix". Don't know why but I always thought that the ED panel was unaffected by this problem...sad to know that it is.

[tomboyter]

Help me Mr. Bruzzi,....is this the straight skinny on the floating black issue?

[hardc0re]

[QUOTE=RichB]I have a 657UY. There is no APL Multi.
There is R,G,B Drive, R,G,B Cutoff, All Drive, All Cutoff. That's it.

Of course, I may not believe my lying eyes ;)

-- Rich[/QUOTE]

I believe it could be that setting is only available on the consumer models. I have a consumer PV500 Asian model, and the setting is available there. There could be a similar APL setting somewhere for the commercial US models.

[QUOTE=rover2002]Have you seen eny negative effects from lowering 'Apl Mult' setting? ie , a drop in black lvl, more chance of burn-in ect?
It would be good at last to have a fix to this issue that many ppl have voiced consern over, but i remain unconvinced !
Why have Panasonic not found this simple fix and got it out to techs in the field?
Why Panasonic WHY?[/QUOTE]

So far I have not seen any negative effect to doing this. I dont think it even affects the panel life or burn-in. Logically it should not make a difference, since overall the image intensity did not change significantly due to this setting.

One change in the image I could see (under much scrutiny) is that the deepest greys will "fade into black" if there is increasing white on the screen. This is not noticeable under normal viewing.

Also, if you consider before changing the APL setting, in the same scenario (increasing amount of white), the black level would go up and "blend into" the deepest greys anyway - this is the irritating "black shift".

I prefer having the dark greys fade to black, than having the black level shift up to blend into the greys.

As to why Panasonic have not mentioned this setting, I believe this could be a combination of these factors:
- Changing a "recommended" setting that has even the slightest chance of affecting panel life might be against policy.
- The US-versions PX500 may not have this setting in the service menu. Note that my set is an Asian/European-version (PV500).
- The "letterbox" setting on the commercial models could be effectively giving the same effect.

[HallertauRogue]

I'll just repeat this before people start thinking all the 8UKs have this issue. I have tested and tested for this issue on my 50PHD8UK. I cannot recreate this issue. My TV is calibrated using Avia and the THX optimzer. I have lowered All Drive (did it right when I got the TV). I'm currently using component cables for DVD and HDTV. I'm using the PC input for a PC. Neither input suffers this issue.

Perhaps my TV, if inproperly calibrated, would display this problem. I'll never know because I don't plan on running it with incorrect settings.

[HallertauRogue]

Just a thought, perhaps we should start listing our service menu params, just to compare. They may not all be default from the factory, thus causing some issues.

[RichB]

There is another fix to disable the auto-dimming function on 7UYs. I have used this on my 657UY and it fixed an issue that I really only saw on DVE going from a black screen to a 10% window. Within a few seconds, the window would flicker and get dimmer. Then if I pressed any key on the remote, include one that brought up no menu, the image would reset. This may be a different source of black level shift than others. I also think this may work on 8 series plasmas.

-- Rich

Edit: Here is the link to the "Black Level Fluctuation" workaround for the "7UY" Displays (http://www.glaucobruzzi.com/plasma-faq/showthread.php?t=164)

[Kevin C Brown]

Haller... Others have reported that the 50phd8uk also has it. Remember, it *is* less apparent on a properly calibrated display. Plus, some displays have it worse than others. But look in the back of the manual, pg 43, the first item in the lower section. It's a design "feature":

"SYMPTOM: The screen darkens slightly when bright pictures with minimal movements are shown. CHECK: ... it is normal and not indicative of malfunctioning."

I dug up a few more settings for the commercial models that will help, but not eliminate it entirely:

Pg 24 of the manual, there is an AGC thing which seems related to floating blacks. "Increases the brightness of dark signal automatically." Can be turned off, which is good.

Pg 30: Peak Limit value: "Suppresses image contrast (peak brightness)." Also can be turned off.

Pg 32: Power Save mode: "When this function is turned ON, luminous level of the plasma display is suppressed, so that power consumption is reduced". Can be turned off too.

[mapson]

Kevin, good finds on the options, maybe someone can clarify if those help. Would Video NR setting on page 37 do anything to help also?

[Kevin C Brown]

I think that NR setting might help for poor quality sources or overly compressed DVDs, but I don't think it'll help with floating blacks.

[Shad0wz]

Anyone have similar proceedures for the consumer models? My 50px50u is exhibiting the same floating blacks

[oldcband]

[QUOTE=Shad0wz]Anyone have similar proceedures for the consumer models? My 50px50u is exhibiting the same floating blacks[/QUOTE]
Having experienced the black shift problem (or what ever were calling it today) on a Onyx 7th generation plasma, I follow this issue very close. Probably the only way you can live with it is to watch your tv in the cinema mode and make adjustments to lessen the effect. Cinema mode won't cut it for me, I liked the vivid mode best which makes this problem stand out. It was just to annoying for me so I ended up with a LCD. Its kind of a catch 22 because when the service center picked up my panel, I thought should I live with it or get another tv. Gave up a little PQ but I think I made the right choice. The only plasma I've read where a work around is the 42phd8uk. And also C-net test there tv's and call this problem poor dc restoration and I've learned all plasmas do NOT do this, but I don't know, I just didn't want to take another chance with plasma.

[fasTLane]

what does dc in 'dc restoration' stand for?

[Kevin C Brown]

(Edited) Not on Bruzzi's site yet, but if you do a little searching, someone did claim they found a parameter in the service menu that fixes this for the consumer models. Beginning of this thread!

http://www.avsforum.com/avs-vb/showthread.php?p=6931813&&#post6931813

And: http://www.avsforum.com/avs-vb/showthread.php?p=6953724&&#post6953724

DC = direct current, I presume.