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How to disable SVM on the tosh rpgs in 5 mins

Discussion in 'TVs' started by 2shy, Feb 11, 2002.

  1. 2shy

    2shy
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    I too was worried that the insides of US and UK models were different, but they are pretty much identical. All you have to do is unscrew the front panel, be amazed by all the wires and boards and then...

    Locate the SVM boards. They are on just above the guns. Now, you only need to stop the power going to the centre green gun, as the other 2 boards get there power from the green one.

    Follow the power cable from the green SVM board (silk-screened as P706B) on the right side of the board to the bottom of the TV into the cable trough. On the lower right hand side of the cabinet, it will connect to the power board. Unplug this connector (silk-screened as P811, it's a real bastard to pull out on the 56incher) and secure it so that it can't come in contact with any other components (twist tie or electrical tape).

    And thats it. I could not believe the difference at first. I mean I have had many rpgs and even a good front projector, but the 56who8 put them all to shame. :cool:
     
  2. matt janes

    matt janes
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    This sounds very exciting but can you describe what the SVM board looks like to someone who hasn't pulled a TV apart before. Is it a computer motherboard type thing??

    My Tosh 50" is still knackered, awaiting the bloody engineer to call.
     
  3. Duncan Harvey

    Duncan Harvey
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    HAve you had any green fringing problems with the 56 incher?

    I still have these problems, which for DVD I can defeat via the chroma delay setting on my player (Pioneer 737) but it does reduce the viewing experience via S video as everyones face, edges etc has a green profile.

    This isnt convergence, as the set has been "in for repair" where they totally ignored my comments re y/c delay and just reset the convergence.
     
  4. HBK757

    HBK757
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    Wooo all done. Took about 20 mins cause I was so nervous :D Mine was a blue+brown connector labeled P704B, there was no P706B on my SVM board (I have the 43VJ13P set). I disconnected the cable from the SVM board and not the actual power board laying on the bottom of the tv case, this was way too hard to get to so I did it the easier way :D
     
  5. bcottis

    bcottis
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    HBK757, How much has this improved/changed the picture quality? If its not required surely there would be a setting to disable it in a menu. If not user then at least service menu.
     
  6. HBK757

    HBK757
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    The option to disable SVM in the service/designer menu exists on American model Toshiba HDTV's but unfortunately we can't do that to European models. As far as it improving the picture ? Well I can't say its made a huge amount of difference to be honest. Images don't seem to suffer from ghosting/interference around the edges of the image as much but apart from that its nothing big.
     
  7. 2shy

    2shy
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    It's alot clearer on my 56inch set imho. I mean those three large circuit boards must of done something to the picture.

    Hell everyone recomends disabling SVM. All those experts can't be wrong.

    For those who dont know what it is:

    S.V.M. or Scan Velocity Modulation affects all luminance transitions as the electron beam scans the CRT from left to right. SVM causes the electron gun to slow down when scanning bright objects. It therefore distorts brightness and geometry for the sake of "improved" contrast and sharpness. It's about as useful as "auto-color". Manufacturers add these worthless items to sets for the same reason they max-out the "blueness" of the color white. That is, to make it stand out on the showroom floor and look "better" to the uninformed casual viewer.

    The text below was taken from some american site:

    Although the set used for the analysis was a USA Toshiba, information found most likely applies to most if not all sets.

    "Errata ... SVM & Toshiba Theater Mode

    On a quiet evening last night, I found some time to take a look at my 36" Toshiba set and tweak the grayscale some more. The set is the CN36G97 unit which is the same unit as the H97 and the current V71 units.

    Moire problems and all, but fortunately, I took care of that problem a long time ago.

    I was curious about colour temp readings at the medium and cool settings now that the warm mode was 6500K. Typically, the medium was 8500K and the cool was 12500K (ghastly to say the least) and to think some people like this setting. Well, with nothing else better to do, I reset the medium colour temperature to 6500K too. Why, because I felt like it. No other reason.

    It was shortly after I did this that I noticed a severe ringing effect on the image. A horrible edging that made the image unbearable. Was it sharpness? Was it contrast? Nope, both were under control. I turned the colour down to zero and the edging was still there and still in colour!!! The image was black and white, but the edging was in colour.

    I quickly switched from my Sharp DVD player to my Toshiba 2109 unit, thinking that there was something wrong with the Sharp DVD player. But when the Toshiba put up the image, again, the ringing/edging. Good Gawd ... it was the TV ... stupid TV .... Grumble grumble. This picture was unviewable in my mind. The edging drove me crazy. So in my momentary fit of depression I switched the image preference setting to Theater mode from my memory settings. Not too different aside from the contrast going up to 50 from the previous 30 position.

    But with this mode change, the edging was gone ... no more ringing, no more added colour artifacts. Yes, it was the SVM at work. I remembered that I had reset the unit long ago and just reset the TV parameters manually, mistakenly leaving the SVM active. I am kind of ashamed to admit it, but I have never been able to objectively look at the effects of SVM until this day. When I first got the set, I went into Theater mode immediately, thus bypassing the SVM. And through all this time, I never ever saw its effect on the image in real time. And here it was ... I could now objectively turn the "feature" on and off and the difference to the picture was most significant.

    Talk about hiding in plain sight ... it was there all the time and I never bothered to look at it. But with this little exercise, I was able to confirm that "Yes" the theater mode does indeed shut off the SVM on the Toshiba directview sets. If there ever was a question of that in my mind, it was answered. Now what bugged me about the SVM effect was that it was there all the time, even at low contrast settings. Truly a bad idea for a TV feature.

    So what is the best way to test the effect of the SVM circuit? Go to the needle pulse pattern in AVIA or VE and toggle between Normal mode and Theater mode in the preference menu. The results should be obvious and startling. The black line in the bottom white field literally thickens to 3x when the SVM is engaged. The KeohiHDTV site has a wonderful presentation/illustration of what this SVM monstrosity does to the image.

    It not only distorts geometry, it adds colour artifacts, it creates artificial edging. And this is a good thing right?

    So if you ever wondered, this is a way to see the effect first hand and decide for yourself.
     

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