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Plasma YUV / JS YUV Convertor problem

Discussion in 'Plasma TVs' started by r22flyer, Nov 15, 2002.

  1. r22flyer

    r22flyer
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    OK - I'm stumped with this one (and so far JS is too!)

    I have a SKY Digital RGB SCART going to TIVO going to a brand new Pioneer DVD656A player then RGB to YUV with a JS convertor box to Panasonic PW4 plasma.

    The problem I have is - on very bright scenes (almost all white) the plasma picture 'tear's gradually around the top 100mm or so...

    Scene - Star Gate DVD Directors cut - explosion of pyramid ship at time index approx 115 mins.

    Now the strange thing is that if I play this scene via my JS VGA converter box, s-video, composite video, or via the DVD's YUV direct to plasma YUV then all is well - it only happens when using SCART RGB to YUV conversion.

    To be fair I have also tried the Lektropacks CSY2100 SCART to YUV convertor and it too does the same but worse....???

    I have also tried the DVDs RGB SCART output direct to a Sony CRT TV and all is well too...

    Anyone had this problem or anything like it or can shed any light on a fix....???

    [I'll post a pic if I can figure out how to]
     
  2. r22flyer

    r22flyer
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    Photo of problem....

    [​IMG]
     
  3. Guest

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    Hi Paul

    Sounds Like a Question for Doctor J Sim I,m sure he can find you a solution with a little time.
     
  4. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    This is going to sound strange idea but...does the TIVO have a CONTRAST setting ni its vide set up. Sky boxes do. If it does set it to minimum (picture will look too dull but do it anyway) then see if it does it.

    If the DVD player has a contrast setting try turning it down too and see what happens.


    Gordon
     
  5. r22flyer

    r22flyer
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    Gordon,

    Very interesting...

    The brightness, contrast, chroma settings etc on the DVD player were all set to the default central positions (never before adjusted) however lowering the contrast 2 or 3 stops eliminates the problem....

    Does this lead to some conclusion (other than leaving it set like this!)....

    Cheers,
    Paul
     
  6. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Do you have an AVIA test disc? It wouldn't surprise me to find that the factory defaults for contrast combined with certain DVD's may be overdriving the input of the plasma.

    Tell John what you did to sort it and see what he thinks. I would guess that the image will probably look more detailed in bright scenes now with the contrast at this setting.

    Gordon

    P.S. Glad it's a sort of result!
     
  7. symanski

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    Just to let everyone know, I am working with Paul on this one to find a solution. There is a lot of work going on behind the scenes to find a solution.

    I have the same DVD as Paul and have tried it on my system, but don't have the same tearing effect. The difficulty is that Paul does have a different system to myself, so we need to find what's the problem with his. He has been able to do some measurements, which are helping to trace down where the problem is occuring.

    I'm just off the phone with Paul and we're both working on the solution. Adjusting the brightness did help, and it's one area that I'll be looking into further.

    All the best,

    John.
     
  8. phil_evans

    phil_evans
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    Paul,

    I've PM'd you details of a similar issue I had with my specific setup. John has been a pleasure to deal with and went to great lengths to provide me with a high quality solution - I'm sure he'll do the same for you.

    One of the best things about this forum is the small group of dedicated vendors who provide such high levels of customer service as well as significant contributions to the forum.

    Phil
     
  9. Guest

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    add my Tuppance

    I was at R22flyers place on sunday and saw first hand the ripping problem, and it really is awful and it was doing it on more than just Stargate, most DVD,s we tried with a bright scene

    the picture kept giving this "ripping effect" and to my mind the Converter must have some kind of issue with the Pioneer 656

    Nice to see Phil back posting again, thought you must of been away taking some more of those awesome Icelandic Piccies again
    :D :)
     
  10. symanski

    symanski
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    Party Animal,
    have you tried your Pioneer DVD player in R22Flyer's system?

    All the best,

    John.
     
  11. Guest

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    Originally posted by symanski
    Party Animal,
    have you tried your Pioneer DVD player in R22Flyer's system?

    All the best,

    John.

    ------------------------------------------------------------------------------

    No I have,nt John but as soon as I arrived at his house and found out he had bought the 656.

    my first worrds to him was " I should of brought my dvd player to test it"
    , but I,m sure me and Paul can arrange a quick test session, we Live about 12 miles apart but I will sort something out with him
     
  12. symanski

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    Party Animal,
    thanks, I'd really appreciate it. I'm going to get a replacement unit down to R22 too.

    All the best,

    John.
     
  13. r22flyer

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    Ok - the latest news...

    Party Animal kindly brought his Pioneer DVD player and we tried the Stargate DVD though the YUV converter - problem still exists...

    We also tried an Hitachi DVP515 player - problem still there too...

    So we are convinced its not the DVD players at fault...

    Over to you John... any replacement YUV converters ready yet...

    Paul
     
  14. symanski

    symanski
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    Thanks for your email. As I replied to your email:

    "I've had the output of the converter and of a US DVD player on a digital storage scope. Other than you have different data bursts at the start of the picture, the outputs are identical. Both are 0.7V for the picture, with 0.3V for sync. This was using the Avia test disc, with a complete white picture at full output."

    Investigations are continuing. A replacment box will be sent out, as previoulsy discussed.

    All the best,

    Dr John Sim.
     
  15. r22flyer

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    Latest update....

    A couple of internal mods suggested by John have been tried and have improved matters.... if I try to quantify I would say improved by 75% but John has run out of ideas for now and the matter remains essentially unresolved...

    Fortunately only one DVD from the dozen or so I have watched over the Xmas hols has had any full white screen to show the problem....
     
  16. JamesTapp

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    Throw it in to see if it helps...

    Never had any problems with tearing from my DVDs.

    I have a similar set up:

    NTL -> Tivo -> Sony NS 900 -> JS RGB/YUV.

    However, my PS2 does cause problems. Turning down the brightness on the game settings or on the plasma itself cures the problem as Gordon suggested.

    Kind Regards,

    James
     
  17. symanski

    symanski
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    Quite a bit of work has been done on this behind the scenes, to re-verify the design and to compare with other component video enabled devices. Comparisons between the converted picture and normal component ouput shows both are identical. So, the converter does seem to be correctly converting.

    One theme that seems consistent is that the RGB output from the affected DVD player seems too high. Since this is converted by the unit very faithfully, the output is subsequently high. This then seems to saturate the input to your screen.

    Another person affected by this added resistors to the input of the converter so that the level of the RGB input is reduced, thereby reducing the brightness. This solved the problem.

    A similar modification can off course be added to the inside of the converter. However, this then wouldn't be strickly accurate as the brightness output wouldn't be that of the input - but since the brightness of the DVD player was too high to begin with, it should be in balance.

    All the best,

    John.
     
  18. BigH

    BigH
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    Hi,

    I can add something to this one!

    I just taken delivery of the 50" panny (PW5) and initially I fed it composite and S Video signals - I was awaiting delivery of a JS RGB-Component box at the time and had no choice. Picture was not optimum (as expected) however otherwise all was well (apart from some lip sync problems).

    The JS box arrived today and I duly hooked it up, hey presto - picture improvements and lip sync problems improved (almost disapeared,

    However I have noticed something else, instances of screen break up during some periods of extreme video change ie fast motion combined major light changes, one of the execution sequences in the Greem Mile showed several seconds of Video break up. I also saw some break up during the Matrix on one seen when it went black between chapters and took a few seconds for video to reappear. Interestingly I did not see this before I hooked the system up through the JS box, I might add that I had also not extensively tested for it either. I will give a go when time permits.

    Apart from that the images are superb despite the sources not being the highest calibre.

    System is currently as follows:

    Panasonic TH-50PHW5
    Pioneer DVD DV 636
    Panasonic Sky digital box (TU-DSB30)
    Panasonic SVHS video NV-HS980B
    Sony STR-DB940
    Kef 2005

    Hooked up as follows:

    Sky>scart RGB to DVD (loopthrough)> scart to JS RGB/component>RCA cables to panel
    VCR >S Video to panel

    Any feedback for system improvements/solution would be appreciated.

    Regards,
     
  19. r22flyer

    r22flyer
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    John,

    You really need to nail this one down....

    This is now at least 2 instances of Pioneer DVD players used with JS converter boxes showing this image tearing/disturbance....

    It may well be that the Pioneer output is slightly too high and is overloading the converter (as per our PM) but I find it difficult to accept that Pioneer would get this so wrong...

    Also it doesn't happen with your scart/vga converter - is the plasma vga input or vga converter more tolerant of high signal levels?

    Are there any trade contacts out that can loan JS a Pioneer 636, 646, or 656 DVD player to test and measure the output in his workshop so we can see how best to eliminate this problem...

    John, if it is simply a matter of reducing the signal levels, how about a scart through box with some selectable attenuation/bypass settings [if not a production version maybe something of a prototype to loan out to prove the theory].

    John, you mention this was solved by adding resistors inline - can you send me the resistor values and circuit so I can try it if I have time?

    To be fair to John, other scart to component products available are much worse at handling this problem (I know, I have tried one).... and I have to say that the JS boxes are very well made quality items so performing better than other products BUT there is this doubt over the component converter...

    However John, is it fair to still keep using my endorsement on your web site if I'm still not 100% happy....?

    Ever patient,

    Paul
     
  20. BigH

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    Hi all,

    I am more than happy to try one or too things to try to identify the problem. If it is a signal level problem I am more than happy to butcher a SCART lead and isnert some resistors. I also plan to make a SCART to RCA lead to hook up the RGB and composite (sync) directly from the DVD to the panel. This would not be the same signal type (ie RGB sync compared to YUV) but it may help. I find it stange that Pioneer would get the signals wrong, considering these are also different models. Having said that "sods law" may well be applying itself in this case.

    I might see if I can borrow my neihbours DVD player and plug it into my setup with the same DVD and see what happens.

    I'll post any relevent results.

    Regards.
     
  21. symanski

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    Paul,

    what we do know is that the Pioneer is outputing 1V Pk-Pk, rather than 0.7V Pk-Pk as per your measurements. Video is supposed to be 0.7V Pk-Pk, so the Pioneer seems to be over driving the outputs. This is only a problem in bright scene where it's 100% IRE (white).

    Over driving output is a trick that's been used in audio equipment to make one appear to perform better than another, but it's was simply louder. In this case, the DVD player's output would appear to be brighter in normal scenes that comparitive ones.

    I have managed to borrow a Pioneer DVD player, the 747, and it's output is fine. Going to the converter, and out it was fine. Comparing between converted and component output of the 747 (since it has both) there wasn't any significant difference. I have repeated this experiment with other DVD players.

    As you state, there's other converters which suffer from this to a higher degree than my converter. This suggests two things, first, my design is is performing better under these extreme conditions, and two, there's an under lying problem with the output from the Pioneer which needs to be addressed.

    That said, you do know that one is working on this. There are thousands of different A/V products and one simply can not test on every single device. The component converter went through the most riggerous testing proceedure of any previous product, but as of yet we've not been able to repeat your problems here.

    I will email you the requested resistor values.

    All the best,

    John.
     
  22. NeilMcRae

    NeilMcRae
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    JS boxes work fine with my Panny and Sony DVD player. Looking at the discussion I'd say the Pioneer DVD player is the device with a fault...
     
  23. notsew

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    Kicking this thread back up. Was a solution ever found to this problem? I'm having the same problem with Pioneer 545 (see my post today)
     
  24. r22flyer

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    Unfortunately a technical solution was not found so John Sim agreed to refund in full if I returned the RGB to Component converter - which I did...

    I now use a Quintro SCART switch box the output connected to a JS SCART to VGA converter. The picture quality is excellent and no tearing or glitches. This is actually much more convenient than my original set-up with some auto switching taking place when units are powered up. The audio switching is much more elegant too.

    As it happened another Pioneer unit tried also showed the same fault so the DVD player is not uniquely faulty but it is possible that Pioneer players drive the output levels a little too much. Anyhow, I don't care now cos it works via VGA perfectly.
     
  25. notsew

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    Thanks for the feedback Flyer. I'm going to keep the JS box for use with NTL digital cable (works very well). I'll use the 545 with a s-video output upconverted to component through my soon to be delivered Dennon 3803, until that is I can justify the price of a new prog scan player.

    John
     
  26. symanski

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    Hi notsew,
    what we found with some Pioneer DVD players they were outputing a higher level of RGB than they should. The converter faithfully converts the RGB to YUV, but the results are higher than they should be (faithful conversion - too high a signal in results in the output being similarly too high).

    One workaround with the Pioneer is to reduce the brightness setting if you have on in the player.

    We've tested with a variety of sources, and can demonstrate that the conversion process is very accurate and faithful.

    All the best,

    Dr John Sim.
     

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