KD-34XBR970 Distortion Issues - AVS Forum
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post #1 of 20 Old 12-23-2011, 04:29 AM - Thread Starter
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So I barely managed to get this beast of a TV into my home. Picked up a used one for $50. While I realize it's not as good as the 960, it will do for my needs as I've been using a 20" Wega since around 2000 (It's still kickin!).

So anyway, I've got it hooked up, but on testing with HD sources I'm seeing distortion on the lower center edge of the screen showing a slight upward bowing that distorts straight lines at the very bottom. This is pretty noticeable to me, so I'd like to correct it if possible. I also have a very minor downward bend on the top left and right corners. The top center may have a slight downward bow as well, but I believe that's just an illusion created by the edges curving down slightly. Finally there is a slight inward bow in the bottom left. I've attempted to recreate the effect in Photoshop on the convergence test grid. The liquify tool messed with the alignment of the lines a bit so you'll see weird pinching along the bottom row of squares that doesn't existing on the TV... but the bottom edge is roughly correct to what the image looks like on my screen.

Can anyone recommend service menu adjustments to look at that might help with this? I've played around for a bit without much luck. Barring that, it seems like I don't have a lot of options since CRT techs are probably hard to come by these days.
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post #2 of 20 Old 12-27-2011, 05:18 PM
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FWIW, I would try to help you out, but I think the geo controls on your model may be different than on my 34XBR800, because there are no Zoom/Stretch modes on my TV for 720p/1080i HD resolutions.

...And I don't wanna screw yer TV up.

You might find some tips here on you model though.

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post #3 of 20 Old 12-27-2011, 05:30 PM
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On the outside chance it may be of some help... here's a handy-dandy table you can use to enter the original values for your geo controls, to switch them back if you don't like the changes. (Under NO CIRCUMSTANCES WHATSOEVER!!! should you try to reset the data in the SM, because you will erase crucial factory tweaks on the TV that will make it unusable!!)

Many of the geo controls are context-sensitive and can store different values depending on the resolution and zoom/stretch mode, so you should record the original settings for all 4 zoom/stretch modes for both the SD and HD resolutions, before making any changes.

        SD: 480i/p HD: 720p/1080i
Category Item # Item Name What It Does Wide
Zoom
Normal -Full- Zoom -Full- Zoom Horiz.
Expand
Vertical
Expand
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       
                       

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post #4 of 20 Old 12-27-2011, 05:45 PM
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There are some patterms that may be of some use starting with this post as well.

They are all in DVD resolution (720x480 pixels). But you can scale them to other resolutions, if it makes it easier.

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post #5 of 20 Old 12-28-2011, 03:46 PM - Thread Starter
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Thanks for the input. I've gone through the service manual, as well as I can decipher it anyways, and I've tried playing with some settings without saving without much luck. So now I'm hoping to get some more specific suggestions. It has a sort of uniformity that makes me feel like there should be controls without actually finding settings that seem to do the right adjustments. :\\

I can lower the center with VCEN, and then make some adjustments with VPIN, and while sometimes I think it looks a little better, at the same time it doesn't. It feels like the right direction considering the distortion I'm getting but unfortunately the results I'm getting don't seem like a fix.

There's a similar grid in the Sony thread you linked to, which I have read over previously. The image I adjusted to show the distortion in my original post uses that as a base. If you can think of a reason why one of the other grids would be a better option to go with, I'm certainly happy to do so!
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post #6 of 20 Old 12-28-2011, 04:35 PM
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I'm currently looking at buying on on CL but it's for $80. I have other other options for $35 but they are older and aren't 16x9. They said it's working fine but when I go to take a look at it, I will make sure to see if the TV is doing the same thing.
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post #7 of 20 Old 12-28-2011, 05:37 PM - Thread Starter
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As a big plus, it's the last set of it's size made for the US, so it should have a lot of life in it. But really it's a cheaper version of the 960. For me it's still totally worth it. Even with the geometry issues. I just hope that I can fix them eventually.

The two big downsides of the 960 for me are no Twin View, which would be really nice to have, and no super fine aperture grille. But at this point if you want to be cheap you can't be that picky,

You will also bring 3 friends/family members who can't leave you hanging. It very, very heavy and very awkward to move.
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post #8 of 20 Old 12-28-2011, 06:10 PM
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Nah, I used to own the XBR700 and that thing weighed 300 pounds and need 3 guys. My friend and I can lift the XBR970 no problem. I will even bring my skateboard to make it easier to get to the car. I am trying to talk them down from $80. It's been listed for a week so I know they aren't getting hits on it.
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post #9 of 20 Old 12-29-2011, 05:43 PM
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Quote:
Originally Posted by dranore View Post

Thanks for the input. I've gone through the service manual, as well as I can decipher it anyways, and I've tried playing with some settings without saving without much luck. So now I'm hoping to get some more specific suggestions.

I'll get back to you with more on this soon. If you can post an actual photo of your CRT displaying a grid like this that might also help.


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post #10 of 20 Old 12-30-2011, 05:07 PM - Thread Starter
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I took the grid you posted, stretched it to 1920x1080, and took a photo on my unit. I've attached the original grid, the photo, and the two combined aligned so that the center lines are overlapping.

As you can see there is a downward bow on the top left and right corners and the bottom middle has a distinct upward bow. As such there is a distinct "V" pattern vertically where the corners and the opposite side's center seem to have parity.

Please let me know your thoughts. The more I look at it, the more it bothers me!
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post #11 of 20 Old 01-04-2012, 03:14 PM
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Good deal! Precisely what I was hoping to to see.

First, let me say that I've seen much worse geometry situations than what you've posted. And from what I've seen here, that slight upward bow is quite common on the Sony HD tubes. That's the "good" news. Now for the not so good news...

All I can really tell you is how I'd approach the issue on my 34XBR800 TV, which may not be correct for your TV because it has the add'l zoom/stretch features for HD signals. That's why I suggest poking around a bit to see if you can find some more info on the geo controls for your specific model.

The upward bow on the bottom and "downward bow" on the upper corners are really the same issue. You've got an upward bow distortion that's effecting the entire raster.

Fixing that can be a bit tricky because there's only one control for vertical bowing (2170D-1/VCEN) and it's a "global" adjustment (on my TV anyway)... meaning it only stores one value, and applies it to all resolutions and zoom/stretch modes on the TV. So you cannot tweak the vertical bow differently for 480i than you do for 1080i, for example. One VCEN value has to work for all resolutions and zoom/stretch modes on the TV.

If the distortion is pretty consistent across all of the zoom/stretch modes for both SD and HD signals, then it's a little more manageable. But you should be aware that changing VCEN for one resolution and zoom mode will effect the geometry on the other resolutions and zoom/stretch settings on the TV.

Before you attempt to make any tweaks, I'd recommend that you look at a grid pattern like the one above in all of the zoom/stretch modes on your TV using both an SD (480i or 480p) and HD (1080i) video input, to see if they all exhibit the same upward bow distortion... unless you don't care how the picture looks on the SD sources. (I only use 1080i on my 34XBR800, so I didn't even both worrying about or fixing the distortions on SD zoom/stretch modes.)

Anyway, that's the first issue you have to contend with. The other issue is that VCEN will tend to shift the raster upwards or downwards a bit. So you may be able to fix the bow distortion, but your image could be shifted off center toward the top or bottom of the screen as a result. To correct that you'll need to use some of the vertical position controls. And the amount of shift may be slightly different for SD, HD, and different stretch/zoom modes. So you may need to make small tweaks to re-center the raster for all the different SD and HD zoom/stretch modes.

There are a couple different controls for vertical position. (Edit: See note in Post #14 below about vertical controls in the User menus that I forgot about when originally composing this post.) The most obvious one (in the Service menus) is 2170D-1/VPOS. This is also a global control though, which only stores one setting for all modes and signals on the TV. And you may also find that it "interacts" with the VCEN control in such a way that it tends to undo the corrective tweaks made to VCEN.

There is another vertical position control in the SM that you can probably use to get around this problem: 2170D-1/SCRL. On my TV, SCRL is sensitive to both resolution and zoom/stretch modes. IOW, it stores different values depending on the zoom/stretch mode the TV is set to, and whether the input is SD or HD. So this can potentially be used to re-center the raster for other signals and zoom/stretch settings. My suggestion is to leave VPOS at or near the original setting on your TV, or around 31. And consider using SCRL to tweak the vertical position of the raster (if the vertical controls in the regular User menus don't suffice).

There are other vertical position controls in the MID group settings as well, but I recommend staying away from those, because they have even more complex interactions than the ones discussed above. Whatever you do, DO NOT change any of the sizing controls in the MID groups, because you can potentially loose lines of resolution in your images if you do that. The MID settings are digital controls, while the geo controls in the 2170D-1 section are all analog, so there is less potential harm that can be done with the latter. If you do not have a precise idea what a control does, it's best to leave it alone and not touch it, or you could screw things up on your TV.

VCEN and 2170D-1/VPIN are also inter-related. VPIN is the vertical pin cushion control. The basic strategy is to adjust VCEN so that the bow distortion is symmetrical, and there's either a slightly outward bow on both the top and bottom edges of the raster, or a slightly inward bow on both.

Imagine that the lenses in this illustration are the video raster on your TV. The top lens is "double-convex", and the equivalent of a symmetrical outward bow. The bottom lens is "double-concave" or similar to symmetrical inward distortion. Obviously the distortions would be much more subtle on your TV. But if you can get the distortion symmetrical with VCEN, then you can fix any remaining pincushion effect left in the image using VPIN. (VPIN is also a global control on my TV, so there's only one setting for all zoom/stretch modes and resolutions.)

A ruler is your friend. Don't trust your eyes. The patterns that I supplied in the Sony SM thread are ruler accurate, so if you measure from the bezel of your TV to the edge of the grid at different points along the bottom or top edge of the screen, the distance should be approximately the same.


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post #12 of 20 Old 01-04-2012, 04:56 PM
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I just bought this TV for $50 today too(well technically $70 since gave a friend $20 to use his truck and help me lift the beast). I need to move the image a little to the right. The left side is a little bit too far over. I made a thread about it but maybe I can get it answered here. I also think the picture is just a tad blurry.
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post #13 of 20 Old 01-07-2012, 07:56 PM
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Quote:
Originally Posted by ADU View Post

There are a couple different controls for vertical position.

Whoops! I'm so used to fixin this kind of stuff in the SM, that I FORGOT these TVs have vertical position controls in their User Menus as well. Sorry about that. (Note to self: always RTFM first! )

According to the 34XBR970 manual, there's a main Vertical Correction adjustment in the user SETUP menu. And also vertical position and sizing controls for the Zoom and Wide Zoom stretch modes in the user SCREEN menu. It might be simpler/easier to make some or all of the vertical tweaks with these controls, rather than using VPOS and SCRL in the service mode.

If the controls in the SM work better, then you may want to zero-out the vertical adjustments in the User Screen & Setup menus before tweaking the position controls in the SM.

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post #14 of 20 Old 01-07-2012, 08:03 PM
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Quote:
Originally Posted by Freeze Time View Post

I need to move the image a little to the right. The left side is a little bit too far over.

Regrettably, I don't see any controls for this in the User Menus. So if you want to fix it, your only option may be to go into the TV's service mode (which should always be approached with some trepidation.)

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post #15 of 20 Old 01-11-2012, 10:53 PM - Thread Starter
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ADU:

Thanks for the thoughtful response! I'll give your suggestions a try this weekend and let you know how it goes.
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post #16 of 20 Old 01-13-2012, 10:04 PM
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FYI, I will be uploading some new grids to the Sony SM thread tomorrow. The new grids will be the same as the others, except they'll have a 15% gray background to better approximates the average picture level (APL) of video over time than the black background in the current grids. The new grids should improve the accuracy of pincushion settings for typical video content (though the difference in the actual settings may be inconsequential).

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post #17 of 20 Old 01-15-2012, 09:01 PM - Thread Starter
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Hi ADU,

Thanks for the thorough explanation. It was helpful in understanding that I'm going about things the right way.

I've tried your new test patterns, and I've played with the settings (haven't saved any yet). The best combination seems to mostly fix the horizontal bowing at the center, but leaves a slight pinching of the left and right corners of the grid... a sort of inverse of the original issue? Still annoying to look at.

The settings needs to be pushed pretty far to achieve this. VCEN goes from 16 to 5 and VPIN from 24 to 8. With a couple of clicks to SCLR to center. Setting VPIN to 16 instead of 8 gets the center and the corners inline, but then the "quarters" are off (a sort of sine wave like distortion). It seems like I can make it better/different, but not "right"? 8 seems better in some ways.

I'm using a yard stick to verify my lines are straight... and I can't seem to get everything to to fall into place. I was using the following patters as it seemed to provide the best frequency while not confusing my eyes or being too sparse.



Are there any settings that I might be able to tweak to tweak the vertical pinching of the left and right? Couldn't seem to find anything...
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post #18 of 20 Old 01-18-2012, 06:10 PM
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What you are ultimately aiming for is something which looks like one of the following two images.

Ideally, You want the geometry as ruler flat as possible in relation to the TV's bezel and/or the black mask which surrounds the edges of the picture tube itself, just inside the bezel.

(You can also use the edge of the CRT mask as a guide/straight-edge to adjust the top and bottom edges of the raster as flat as possible, if you find that easier than measuring with a ruler.)





The geometric distortions will be worst around the edges of the video raster. So sometimes it's difficult to get those edges perfectly flat, especially if you're using little or no overscan.

If you can't get the outermost edges of the 2.5% overscan grids as flat as you want, then you could try the 5% overscan grid instead... Or you could use the 2.5% overscan grid that's divided into 8ths, and try to get the grid lines 1/8 of the way from the top and bottom of the screen as flat as possible, using a ruler to measure from the bezel, as shown below... (<- This approach may actually work best.)



You can also measure from the CRT mask (instead of the bezel), if you find that easier...



There will probably still be a little distortion around the very edges of the screen, but that shouldn't be too visible on most normal video content. If it really bothers you though, then you could probably leave just a tiny bit of outward bowing (pincushion) on both the top and bottom edges, if you find that more aesthetically pleasing.

AFAIK, on my CRT there are no controls to fix the slight irregularities that you're talking about on the top and bottom edges 1/4 of the way from the sides of the screen. VCEN, and VPIN are pretty much the only controls I've got to work with there.

MINOR NOTE: the 2.5% overscan pattern that's divided in 8ths is not quite as accurate for overscan adjustment as the other patterns because there was no way to perfectly divide the width of the image by 8, and leave an exact 2.5% on the sides. Consequently, it's probably closer to 2.75% or 3% on the sides.
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post #19 of 20 Old 01-19-2012, 09:15 PM
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Quote:
Originally Posted by ADU View Post

...Or you could use the 2.5% overscan grid that's divided into 8ths, and try to get the grid lines 1/8 of the way from the top and bottom of the screen as flat as possible, using a ruler to measure from the bezel, as shown below... (<- This approach may actually work best.)


^ If you are going this route then you may also want to make some tweaks to 2170D-1/VLIN & VSCO as well to ensure that the spacing of the grid is even from top to bottom. On my 34XBR800, both VLIN and VSCO will store one setting for the SD Wide Zoom mode, and another setting for everything else.

VLIN adjusts the position of the middle grid line in relation to the top and bottom edges. The distance between the middle of the grid and the top and bottom edges of the grid should be the same as shown below...



VSCO vertically pinches or expands the video raster towards or away from the middle gridline, so it should be adjusted so that the 1/4 and 1/8 grids are as uniformly spaced as possible (after VLIN is correctly adjusted)...





Welcome to the Sony CRT geometry rabbit hole btw!
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post #20 of 20 Old 02-11-2012, 04:18 PM
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Might also want to look at 2170D-1 UVLN and LVLN.

Like VLIN and VSCO, these also store 2 different values on my TV, one for the Wide Zoom mode, and another for everything else. On my TV, UVLN and LVLN are both set to 4 for the Wide Zoom mode (which I don't use), and 0 for "Others".

These controls allow the upper or lower edges of the raster to be moved independently.

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