RPCRT Overscan Reduction - SHIMMING - Page 2

Gotcha. I think I'll leave this to an expert. Anyone have any spare pennies and recyclables?

Thanks for the kudos guys, good to see so many people finally having a go at my “shimming mod” as Bob likes to call it.

Working links to my old posts.

http://archive2.avsforum.com/avs-vb/...frame+overscan

http://www.avsforum.com/avs-vb/showt...2#post14085492

I just shimmed my 65813 by a full 3". I wanted to start high and work my way lower, if necessary. I had to use pliers (Robogrip) to bend the vertical edges of the metal "tray" on the fron side--they were just barely hitting the underside of the styrofoam above. It looks like it's going to work at 3"--just barely. After setting all of the fine/coarse/JUNGLE settings to factory defaults a la craigr's method. I had to increase VHGT in JUNGLE by the max allowed according the the service manual (I think it was like +10 for SD & +5 for HD). It makes sense that the shimming mod "shrunk" the picture that is actually hitting the screen, so an expansion would be necessary. This was to get to around 4% overscan--I think the template gets me 4.38% or something like that, so I should be good.

Also, red and blue ran out of picture at around 2% overscan on opposite sides. I don't think this will matter if I use my Lumagen to reduce overscan from 4.38% down to 1% or whatever (well, I hope not). Should I use the centering magnets to correct this first?

The other issue is that the shimming raised the picture, so that I had to crank VSTA in coarse green to 99 to center it. I am planning to add door stops a la Mr Bob to tilt the whole assembly, and lower the picture back down (and lower VSTA back down).

Thanks Owen & Mr Bob.

Here's what Owen said on that:


Quote:
Originally Posted by joikd
Owen,

I have a Mits. 65813 & a Lumagen HDP. Using the HDP, I can get overscan down to 1% or so (well, 0% if I wanted, but then there's major crap on the edges). Does this have the same effect as the shimming mod? Or, would I still benefit from the shimming mod?


The typical overscan on CRT RPTV's means you get little more then 900 lines on screen, the other 180 are in the overscan area. The Lumagen will scan video to fit in the 900 or so on screen lines which eliminates overscan while still sending a standard 1080i video signal to the TV, the remaining 180 or so lines will have no video information.


The shimming mod shortens the projection light path length which reduces the size of the on screen image, this reduces overscan optically and puts more lines on screen.
There is also the possibility of increasing the raster size (the surface area of the CRT's used for display), this allows scan lines to further apart and is the same as using larger CRT's. The result is more resolution and a sharper more intense image.

After doing a little research I have learned that Pioneer does not sell templates for geometery convergence. However, I was wondering for the HD FULL mode if there is a default size for the boxes? Should I try to make sure they all be the same size with the lines as straight as possible. If the lines are straight but the boxes are different size will this distort the picture?

If I knew the sizes of the boxes, I could use the string method. If I just take an average if what I have now I could make it all them standard. I have the pioneer 610 which is 58".

Thanks

A double post from the F59 Tweaks thread:

Afterreading Summit's post - a question for fellow shimming modders (what a strange term).

Post - shimming....what have been your results w/ geometry after the CRTS are raised?

SInce my F59 was reduced to just under 4% w/o shims, I plan to of course return the set to factory levels first (I still have a 51F59A screen jig,which I plan to use for the first step). Once back to OOB levels, then I will raise the CRTS

Once raised, what kind of geo errors are you seeing/fixing? It is DCAM grid-wide or mainly just some straightening out of the edges?

If any of you did this on a 51", and used the "string method" to correct geo after the shims were added...please let me know the dimensions you used post-shims.
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It's not in the service manual I have but I know there are 2 manuals so maybe in the other

Can't tellya exact box size, but reducing the o'scan on the Elites causes geometric distortion ANY way you do it.

The boxes in the internal pattern are all supposed to be the same size. The bottommost set is always a lot taller than those above it, once you can fully see them, after reducing your o'scan. That's the first thing that has to be done, is make that bottom row of them shorter, same size as the others.

The first row of boxes, farthest to the left, is always wider than those to the right of it when doing the redux via sm only. That has to be taken care of.

When reducing hor size via the H Size in Coarse convergence mode, it only goes so far before it becomes a H Linearity register instead, inexplicably but always. It's better to do H Width via the stand-alone register, the one for HD.

The boxes become non-linear vertically very easily upon reducing the o'scan. You have to go back and forth among them, till they are all the same height, whatever height that turns out to be.

That much I am glad to give away here.

And the first 5 columns of boxes to the farthest left behave in a VERY curious manner, which I am going to keep to myself. Be glad to share off board about that, but it took me years to figure it out, so I'm going to "breast my cards" on that one, sorry...



b

Reminds me of a quote from the Dark Night, as the Joker says about killing the batman, "If you good at something don't do it for free". Yes your free advise has been valuable, and your experience is the "art". Sometimes I have to read your posts 3 or 4 times to get the concept.

I figured out the geometery would be different based on the new sizing so I focused on getting all the lines straight as possible and all the horizontal and vertical lines as evenly spaced as possible. I used the string method which helped me see the cause/effect but it was a lot of work setting them up.

Just luck more than anything, I avoided the global changes that could be made with H size / V size mainly because there was not vertical phase adjustment (equivilent to the static adjustments in the coarse convergence). Also, because the FULL and FULL HD mode required different adjustments. I'm not concern about fixing the other modes like Cinema, Zoom, etc...

After lots of trial and error, due to some geometery issues that I can't correct around the edges, I'm at about 5% overscan on everyside. I used the Veritical static adjustments to center the image, then I had to actually increase the H Size because I had a lot of red bleeding from the left side on FULL HD, and some blue on Right side. That was also ok because it was needed to make the circles perfected anyway.

Funny thing I learned is that 480p signal uses the FULL mode so I see the red bleeding on the right side with this mode. However I can't go into coarse covergence while feeding a 480p single, it does sync well. I will try to use static registers to shift both to avoid this problems. I think this relates to your comments about the tricks with the left columns. I found it very difficult to get covergence working around the top, the top/right and the left most edge.

So far I have easily spent 15 hrs on what is probably simple geometery corrections but then learning curve is high. That does not included about 6 hours for the shimming mod.

I have corrected my top overscan from 10-12% to 5% which is a big improvement (with the centering of the image). The image is starting to improve. I'm now realizing how my greyscale and color saturation is being negatively affected by the brightness being raised to +12 and contrast at +10. I have ordered a Eyeone Display LT and I plan to measure to see just how far off my greyscale is currently. I will then slowly attempt to adjust greyscale using the trimpots for cuts (marking my position) and SM for drive ( cross my fingers).

I didn't say my learnings on the conv errors you have not been able to master are unavailable to anyone. Just unavailable here on the threads for free. As a former corporate call girl appearing on an interview show once said, "I am celibate." When asked what that could possibly mean being that she was what she was, she said, "I sell a bit and give the rest away."

He was caught competely off guard on that one, and said so! Contact me directly - not by pm please - and we'll talk, I'm sure I can literally save you hours and hours and hours more, plus giving you access to many years of tried and true experience and procedures...

What you need to do the grayscale is not just the proper equipment. The learning curve on grayscale is hefty as well, so if you want to add more and more hours to what you have already spent, be my guest, but again phone coaching IS available on these things...

You probably coulda flown me in to do this for you and been money ahead, in the end...




b

Bob - a "free on the forum" level question...

Just wondering in your shimming experiences, are your geo errors all over the place ("speedbumps", etc) or mainly found just around the edges?

Was thinking of getting my set back to OOB o'scan levels & geo perfect via the jig I still have (easy enough to do) and using trhe service manual info on returning the set back in terms of the H/V sizing controls. Once "factory perfect", I would then shim the array and redo to that new size/distance sans jig, of course.

Would think that going back to factory level first would also be good in terms of the operating voltage on the conv ICs. Anything to extend their life is a good thing, I imagine.

The gains from this mod are such that even if I needed to go in & fix geo issues screenwide would be OK. But if the above method might reduce/potentially eliinate all but edge geo issues....well, all the better.

Yeah, I would. You need far less correction in the sm when you do it via shimming, with sm reduced to mop-up rather than the whole thing.





b

I don't think the shimming mod introduced any new problems, I just needed to fix a lot of stuff that existed before like the centering vertically and then some convergence around the outer edges, some of which I have always had problems with.

When I get ready for grayscale I will contact you, I believe you are correct that you can save me many hours of learning curve.

Thanks, Bob. The fewer headaches from dialing out speedbumps, the better!

Of course, if I totally FUBAR something, at least I know you are a phone call & Paypal deposit away!

Still on schedule to try this next month while the missus is away.

I have had these shots in the can for weeks, looking for a good time to do it. Keep in mind this can only be done on virgin-level phosphors, with NO aging footprint. Or on freshly regunned sets.

Will start with these -


Green sides - not bad, perfectly centered

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But not fully utilizing CRT face

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Red and blue - not so good. Very badly centered -

centermost section - almost at the edge

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You can see the edge of the CRT face itself in the background as it goes upward from the edge of the image on it

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outermost section - way far away from the edge

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blue at centermost edge, almost touching it

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outermost edge with WAY more space

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Unlike the green gun, R and B VERY badly centered.

This was what I found several weeks ago. I knew I could not let this stand...





b

Overscan starting point, with badly centered r and b -

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Hwid 37 in sm, vertical taken in a bit to make the circle a true circle via yardstick

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hwid 41, to fill CRT face to max allowable on CRT faces

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vhgt 36 starting value

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40 ending value, expanding pic vertically on CRT face. Pic now fits the entire usable area on each CRT face.

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O'scan redux restored after adding another 3/4" of shimming, to 3" total shim, red corrected on centering, blue not yet

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grid version

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red and blue both centered, but uncorrected. Shimming has recaptured the o'scan redux from before, after the expansion of the images on my CRT faces ADDED overscan to gather more CRT face area

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but notice how much work now has to be redone! curves at the edges, keysoning errors, nothing straight anymore...

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this is what 480 looks like totally uncorrected after the add'l shimming

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and this is what program material looked like uncorrected after the shimming, esp noticeable at the side edges...

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Images recentered and expanded out to fill the available phosphor face. My goal is not to achieve as low as 2%, that's really not necessary, so making the images almost hit the edges won't affect what I DO want to see, which is in from that a bit -


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Green turret/lens. Notice that the screw ends from down below are the same on both sides. Actually on all 4 sides. Its aiming was excellent and as such was not altered. Wish the other 2 guns had been that good!

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Between the turrets, whose screws didn't move much


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Red outside screw ends, showing how much I had to loosen up those screws to make the outside of the CRT come down enough to tilt it properly. They started out with the same amount of exposure as the green screw ends

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Blue - almost nothing left! Quite a bit of tilt, to re-aim the red and blue properly. Put glue on them to make the screws stay, like the LockTite we used to use for immobilzing tape heads after azimuth alignment -

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4th thickness of shim added, to make 3" total for my 73". Had to use 4" bolts!

Nobody ever said it had to look pretty...






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gpounders, I'm not sure if this would apply to your model of Pioneer Elite, but on my unit PRO-730HDi there are hidden convergence points on the top and the right side of the screen. I would recommend getting the geometry as perfect as possible on the bottom and left sides of the screen first and then use those non visible points to correct the top and the right side.

Mr. Bob, or anyone else that may be able to offer some sage advice.

The 65 incher is an absolute BEAST, and before I attempt any shimming, I want to know if I should just not bother.

Anyone that's read any of my posts will know I am a videophile of the most picky nature and I want above all else, as much of the information on the disc as possible on my screen as unmolested as it can be. So of course, shimming seems like a logical thing for me to do next. My question though, is this.

I bought my set used from your typical Joe and Jane 6 pack with a house full of people. The set has no burn in on the original overscan setting, but it was blasting at 100 contrast the entire time they had it. I don't want to go through the trouble of shimming, only to have to put it all back if I can't use the previously unused phosphor area. As I've said before, this set is huge, easily over 5 feet and just enormous. What do you guys think about the probability of success?

Mr Bob would know for sure, but I bet you can pull your screen and look down the lens barrel and see if there is burn in that can be seen if you would do the shim mod since you would use more of your crt face. It would save you alot of work if you did the mod and found out afterward.... thats one of the things thats holding me back too....but I didn't think to check while I had the screen off to clean the lens