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TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

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    TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

    Numerous tests show that the Panasonic UT50 series has a very low MLL in a dark room (comparable to the ST, GT, and VT series), yet my particular TC-P42UT50 cannot not get very dark at all on a black screen. Movies with dark space scenes look washed out and overall contrast suffers for general viewing.

    My brother has a TC-P55GT50 which is supposed to have a similar MLL in a dark room and the black level on his set is much, much, darker, almost imperceptible, while mine is an obvious grey. I suspect that my set made it through quality control without proper MLL testing. And, yes, I've adjusted the set to ensure that absolutely no pixels are activated on a black screen using AVS HD 709. I can turn brightness down to zero and the screen does not get any darker.

    I've scoured through the service menu and TC-P50UT50 service manual and have found no mention regarding how to adjust the black level, nor do I see any trimpots for making such an adjustment. Is there any way to adjust the black level on a 2012 Panasonic plasma? Would it be possible to either make adjustments in the service menu or perhaps install a potentiometer in the appropriate part of the panel's drive circuit in order to make such an adjustment? If not, would the black level be corrected if I replaced one of the boards (assuming the board is out of specification)?

    Thanks!

    #2
    Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

    Originally posted by tom66 View Post
    Must be possible somehow but there's no documentation from Panasonic, I suspect that one of the processors will have an exposed debug port to which commands can be sent but where exactly would be a mystery. I know someone has had some luck accessing a VT50's debug port but they were not able to understand the options available.
    Moved to appropriate thread.

    Like many others, I purchased a Panasonic plasma for its excellent picture quality and dark blacks. Would it be possible to add a potentiometer or perhaps could the issue be remedied by replacing one of the boards? If so, which board controls the black level?

    I purchased this set as a new old-stock item in early 2015, so it is still under the manufacturer's warranty. I'm thinking of taking it down to the local service depot but am worried that they will look at it, see that it turns on and shows a picture and say "It works 100%; no fault found". If so, I would ask them to take it into a dark room and enable the 3D mode, which has a washed out picture with atrocious light gray blacks.

    Thanks!

    Comment


      #3
      Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

      If you look at the screen can you see a subtle scanning line pattern on black? I have a TX-P42U30B and I see that. The black level on my U30B is excellent; it's no Kuro killer but it's probably second only to that in terms of panels I've seen.

      There aren't any adjustments on the SN board as far as I recall.

      Perhaps you should check the hour counter. Older Panasonic sets increase the black level as the panel ages to reduce maldischarge. I think they stopped doing this in 2010, but I'm not certain. I've noticed that pixels on my U30B get a little lazy if they're not used, so an area that's been dark for 30 seconds or slow has a few dead pixels for half a second or so. Perhaps Panasonic tried to eliminate that in later panels. The small 1080p panels are the hardest to make and require a different drive profile to the larger panels.
      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

      Comment


        #4
        Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

        Thanks for the reply, tom66.

        Yes, there is a slight scanning effect visible on a blank screen. The set has around 5000 hours on it. From what I've read, 2012/13 Panasonic plasmas have no issues with increasing black level like the earlier models. FWIW, I almost wish I had an earlier generation, because then it would at least be able to be adjusted/reset for darker blacks.

        Is the SN board the one that controls the black level? I understand that the UT's SN board does not have any trimpots. However, what I was wondering is what would happen if I replaced the whole board? This would be under the assumption that something is out of spec on my SN board which would be put right with a new board. I'm guessing that an overly bright black level is a drive board issue and has nothing to do with the screen. Did they actually calibrate these sets at the factory, or just install the boards and screen, screw them together, and ship them out? Mine was awfully green before I adjusted the white balance.

        I also have my father's old 2008 PN50A550 and blacks on the TC-P42UT50 are noticeably darker; of course, the A550s were never known for their blacks, certainly nothing like a Kuro. It looks to me like the UT50 has a higher contrast ratio than the A550, with brighter whites and darker blacks, although the colour might be a little nicer on the Samsung. However, my UT's blacks are much, much, lighter than my brother's TC-P55GT50, yet both have produced roughly the same MLL in review testing.

        The GT50's blacks are barely visible in a dark room. My UT's blacks only look black if there is a significant amount of bias lighting in the room. I'd be very pleased if I could get my UT's blacks in a dark room to the same level as my brother's GT (which is where they should be as far as I can tell based upon the various test reports I've read). Also, when you say that the 42" 1080p models require a different drive profile, does that have any impact on MLL? From what I recall, the 42" UT models had roughly the same MLL as the larger sets. I could provide some review links with MLL measurements if that helps.
        Last edited by 12Bass; 12-03-2015, 07:27 AM.

        Comment


          #5
          Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

          I also wonder that I am the owner of 3 UT50 series plasmas and notice all three of them have a significant gray showing with scan lines as opposed to my GT30 which is completely black. Of course I'm under the assumption that it could be due to the fact there is no anti glare reflection coating on the UT50 panels as there is with the GT30.
          Did I leave the soldering iron on?

          Comment


            #6
            Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

            FWIW, I've seen some posts reporting similar gray black issues with ST50s on www.avsforum.com. Perhaps some of the 2012 Panasonic plasma do have a black level issue which changes with time? From what I gather, the UT50 and ST50 are generally quite similar, with the ST50 having anti-reflection coating on the screen. In response to the above, I don't think that coating impacts black levels unless there is a significant amount of light in the room. In other words, if the room is dark, then the non-coated screen should appear just as dark.

            See posts #10039 on: http://www.avsforum.com/forum/167-pl...-talk-335.html
            Last edited by 12Bass; 12-04-2015, 03:04 AM.

            Comment


              #7
              Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

              AFAIK all Panasonic's panels are capable of deep black, but specific models are probably "binned" for best performance, as I'm sure if the U30B I have had a lower black level the lazy pixel issue would be more prevalent.

              We have at least one member here who put a VT50 main board into a GT50 set and got the better black level as well as the additional features like THX calibration (though those are probably not valid without the matching AR filter.) They didn't get the better antiglare filter or bonded panel glass of course, but those don't matter too much in a dark room.

              I wouldn't bother with the SN board. I can't forsee a fault being as subtle as that, so I wouldn't try replacing it. The SN board is responsible for a whole lot more than black level, it is one half of the panel driver circuit - no SN board, no picture!

              What I would do, if I wanted to improve black levels, is look for a similar 42" high end model, like a TC-P42VT50 (if such a TV exists), and find the main board for that. If the main board has similar panel connections, I'd try swapping it over with that. It will either work or not, if it works, you get the benefit of a better black level.
              Last edited by tom66; 12-04-2015, 11:32 AM.
              Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
              For service manual, schematic, boardview (board view), datasheet, cad - use our search.

              Comment


                #8
                Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                Revisiting my old thread....

                Now that the warranty has expired, I'm thinking about trying some possible modifications to reduce the black level on my TC-P42UT50, recognizing that any potential damage done is completely my own responsibility. Apart from the disappointing black level, I'm otherwise happy with the television.

                I'm wondering if it would be possible to install a trimpot on the driver board in order to provide adjustment of the MLL, perhaps in the same part of the circuit where the trimpot was located in older Panasonics? While I understand that this would be difficult without a schematic, is the idea of adding a trimpot at least sound in principle? If so, does anyone here have some suggestions on how I might go about adding a trimpot (i.e. which board, approximate location)?

                Thanks!

                Comment


                  #9
                  Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                  The potmeters are not on the y-sus/ss board anymore. They are on the powersupply board. They wont do much beside alternating the voltages which is in this case not a solution.

                  You could try a factory reset and see if it changes anything. Try a new mainboard and see if that makes a difference. Colours are produced by the mainboard.
                  I only repair Panasonic plasma tv's! Currently owning a TX-P55VT50 and still searching for a ZT60!

                  Comment


                    #10
                    Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                    Originally posted by Moreno83 View Post
                    The potmeters are not on the y-sus/ss board anymore. They are on the powersupply board. They wont do much beside alternating the voltages which is in this case not a solution.

                    You could try a factory reset and see if it changes anything. Try a new mainboard and see if that makes a difference. Colours are produced by the mainboard.
                    Thanks!

                    Yup, the only pots I can find are Vsus and Vda.

                    As mentioned previously, I don't understand why the blacks on my set are not dark like they are supposed to be. A variety of instrumented tests have shown that the UT50 is supposed to be essentially equal to the GT/VT50 in a dark room, yet mine is not.

                    From reading about the earlier Panasonics with rising black levels (e.g. 2009/10), it appears that a regular factory reset through the service menu has no effect on black levels. What works on those sets is resetting the hours through the back service port every 150 hours. My 2012 has a similar service port and I'm wondering if the 2010 reset trick might work, possibly with some modification?

                    Assuming I could get a schematic, what I was considering was perhaps installing a trimpot set up as a voltage divider to "fool" the circuit into thinking that the black sustain voltage is higher than it actually is. On my Dad's old PN50A550, there's a Yrr potentiometer which can be used to reduce black levels; I've tweaked it to the point just before random sparkles show up on the screen.

                    By mainboard, do you mean the board with HDMI/component/SD, etc?
                    Last edited by 12Bass; 02-24-2017, 04:16 AM.

                    Comment


                      #11
                      Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                      You can't reset the black levels on this tv. Only with the 2010 models like V10/V20 but the "Black level problem" on these models was fixed in the 2011 models.

                      Yes the mainboard is the board with the HDMI etc and has a GPU which produces the colours/picture etc. Try a different mainboard and see if that changes anything.

                      The UT50 is the "budget" version with a different panel. The GT/VT are the top of the 50 series and the VT50 shows the best picture quality and black levels. So whoever told you that the black levels on the UT50 and VT50 are the same does not know what he is talking about.

                      I repaired many of these sets and trust me , there is a big difference in picture quality between the UT50 and VT50.

                      If you are not satisfied with the UT50 black levels then try a different mainboard and see if it changes anything. IF i can be of any assistance just ask

                      Ps , maybe this site might help you : http://panasonic.mironto.sk

                      BUT

                      " However, they changed the algorithm in 2010 models, so that the increase is less coarse (read users will find out about the rise later if ever). In 2011 and newer sets, Panasonic made significant changes to the internal panel materials which should improve the panel’s characteristics so that there are no voltage adjustments necessary and MLL should stay the same throughout the lifespan of the PDP. "
                      Last edited by Moreno83; 02-24-2017, 11:36 AM.
                      I only repair Panasonic plasma tv's! Currently owning a TX-P55VT50 and still searching for a ZT60!

                      Comment


                        #12
                        Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                        here
                        Attached Files

                        Comment


                          #13
                          Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                          Originally posted by Moreno83 View Post
                          The UT50 is the "budget" version with a different panel. The GT/VT are the top of the 50 series and the VT50 shows the best picture quality and black levels. So whoever told you that the black levels on the UT50 and VT50 are the same does not know what he is talking about.

                          I repaired many of these sets and trust me , there is a big difference in picture quality between the UT50 and VT50.

                          If you are not satisfied with the UT50 black levels then try a different mainboard and see if it changes anything. IF i can be of any assistance just ask
                          I got the UT50's MLL measurements from several reviews of the television, not from word of mouth. Perhaps it lacks some of the refinement and processing found in the higher models, however, several tests showed that the UT50 was just as good for deep blacks, or at least that what the reviewers found when they tested it. I can find the links and post them if requested. Mine was used a demo for about 4000hrs before I bought it, so I don't know if the black levels were always washed out if they degraded as it aged.

                          With regard to a new mainboard, I'll have to look into that. How much would one cost? The European UT50s offer much better calibration, including gamma adjustment, which is lacking the the North American sets. Not sure the the EU mainboard would work, however.
                          Last edited by 12Bass; 03-01-2017, 05:46 AM.

                          Comment


                            #14
                            Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                            Originally posted by tw2005 View Post
                            here
                            Thanks! Will have a look.

                            Am I correct that the Vad is what needs to be adjusted to lower MLL?
                            Last edited by 12Bass; 03-01-2017, 05:48 AM.

                            Comment


                              #15
                              Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                              Do you have the option to turn on "ISFccc" ? Normally you can find it menu / setup/ advanced settings. When enabled you can adjust the gamma settings and play with other settings.
                              EU mainboard probably won't work because you have a TC and in europe its a TX.

                              Find out what board is inside ( TNPH + TXN/.... ) and compare the whole board with the european version and see if you notice any differences. If they are the same then get one.

                              Ps , don't play with VAD....good chance you will damage the panel. ( Search for it on the forums ).
                              Also , the panel is designed to last over 100.000 hours without failure and that's why there are NO potmeters on the Ysus and Zsus. <-- There is nothing to alternate except voltages. ( For sparkles etc ).

                              If the blacks are failing then you either have a bad panel OR bad picture settings OR bad mainboard.

                              Can you post a picture of the picture settings plz?
                              Last edited by Moreno83; 03-01-2017, 02:48 PM.
                              I only repair Panasonic plasma tv's! Currently owning a TX-P55VT50 and still searching for a ZT60!

                              Comment


                                #16
                                Re: TC-P42UT50: Any way to adjust black level on 2012 Panasonic plasmas?

                                Just googled a bit for the review and i found this:

                                "Well, there is no doubt that the Panasonic TC-PUT50 step-up 1080p 3D TV series represents great overall value for the budget home entertainment market. While at under $1,400 for a 60-inch TC-P60UT50, you cannot expect to enjoy the same feature set and refined styling as premium models, the UT50 still comes with one of the best Smart TV suites on the market — an improved version of the much acclaimed 2011 VieraCast, and which for 2012 Panasonic has re-branded as VieraConnect.

                                And while the UT50 picture quality falls shy of the more expensive models from the same Panasonic lineup, this Panasonic plasma HDTV series is still capable of delivering a better picture than most of the more expensive mid-tier and premium models from other brands.

                                However, the UT50 Panasonic plasma HDTVs miss on a number of important features, including the latest Infinite Black panel from Panasonic with the new louver filter. They also have limited user adjustable picture settings which would hinder most serious home theater enthusiast from calibrating these sets for the best picture. In other words, despite its great picture, the UT50 lacks the necessary features and characteristics to represent a serious videophile-grade TV."

                                You either have bad picture settings , for example brightness set to high or you are expecting to much from this model. As i said before , i have seen these models and i own a VT50 , its a huge difference ...

                                Hope we can sort this out so you can enjoy your tv! Ps , im not trying to downgrade this model , its a great tv but it lacks options.
                                I only repair Panasonic plasma tv's! Currently owning a TX-P55VT50 and still searching for a ZT60!

                                Comment

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