RPCRT Overscan Reduction - SHIMMING - Page 3

Makes a lot of sense, I'm going to look tonight.

That's my initial worry. I just don't want to tear it all down, only to find there's screen burn around the edges and I have to put it all back. But the suggestion to look down the lenses might work. We shall see!

The shimming mod is good for o'scan redux even if the phosphor faces do have aging footprint on them. It's better if they don't, but that does not negate the positive effects of using what they do have, that is currently going to be unused if you leave it the way it is.

You just have to aim the guns correctly mechanically rather than aiming the raster ON them, which would make it scan a different area from what's currently at play, exposing the difference in age between the old and new phosphors.

To know for sure, take a flashlight in there and stare down into the CRTs thru their lenses. If you can see the aging footprint, then your options are limited. If you can't, then you're a lot better off and can do what I did with mine above.

Another way is to put up the HD DVE o'scan pattern, expand your sm h and w till that pattern fills a lot more of the CRT face than it regularly does, and see if there's a line of demarcation between the old phosphors and the new, while looking straight into each lens to the CRT below it. Old being darker, new being lighter.


b

Mr Bob,
I'm looking at your photos in post #56 of how you are re-aiming your crts.
So you are adjusting the angle of the entire crt assem from underneath with the screws, the tips, on top, that you can see in your photos. Is this correct Is this different from your cantilever tech? I tried to do you cantilever tech a few years ago but I must have been doing it wrong I guess....

I loosened the screws holding the lens barrel to the plate and tried to re-aim them with washers, to hold the lens postion, while the crt's were in there same position. (By the way now when I try to see it on Keohi i get a virus/spyware warning that the website wants to download something), so I didn't review it now.....Maybe by reading it years ago I misunderstood the procedure......

Anyway, how I see you doing it now makes much more sense to me, since your are tilting the entire crt to the best angle. So are you tilting the red and blue away from the green or toward the green crt? Without actually having done this myself, I'm guessing your top to bottom angle may be unchanged but left to right will have to be adjusted for sure.....

Top to bottom is not at issue. There's more than enough room to move there, since the image is oblong 16x9 on a square'ish 4x3 CRT face, leaving LOTS of unused area at top and bottom of the face itself.

The outer screws of the red and blue gun, when loosened up, will tilt the projected r and b gun contents OUTWARD. Which is what I needed, in my set's case. Do the imagining I needed to do, with what happens when you move the array closer to the screen. If you do so hugely, the images have separated a lot from each other. But you have to counter that by noticing that the images are upside down and backwards when you view them thru the lenses, so everything becomes opposite of what you would otherwise expect.

Anyway, that's why the outer screws needed to be loosened in my set's case, with the inner ones closest to the green gun loosened just enough so the pot metal of the CRT frame holder will not break, then snugged up again and solidified with the glue once the outer ones have been set perfectly.

BTW, this has nothing whatsoever to do with the Cantilever Technique, which is my optical focusing technique. The CT does have to be redone anytime the shimming op is changed, tho. You'll see several marks on the green gun, in my pix, from the several times I have had to redo it so far.

It just doesn't have anything to do with aiming the r and b guns.


b

Ok, thanks Mr Bob, I got what you are saying......

Didn't notice till everything was uploaded that my camera tilt was off!

Sorry, ain't gonna go back and shoot 'em all over again. These are just some of the total I just shot. Took a long time.

Just know that it was the camera being tilted, not the display!



These were all shot at 1.2MP on my Kodak Z712 IS, on tripod and 2 second timer'd, of course -


b

Sprint commercial

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24

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Casino Royale commercial

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Evening news

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Test patterns. Remember the tilt is at the camera, not the display -

Took vertical sizing in a bit to accommodate the offness of the DVE pattern, which is slightly oval, vertically, when sized properly at the edges. I set my roundness using a shot of the moon, on a broadcast show, I believe on PBS. I am sure it will now match the perfect circles on the ABC and CBS logos as well.


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Final Mits sm settings for height and width

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Joe Kane grid at low contrast

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Looks like you got it just under 3% - and PERFECT!

Very nice!

Man, that just looks great.

I bet there is a noticable improvement from your 1st shimming.

and,

After you get some time enjoying your set could you post a mini review or some comments on what your viewing experience is now like compared to where it was when it was mounted by factory? Not a lond review but I'm sure you can evaluate what you are seeing now compared to before quite well....


thanks

Will do. I know I REALLY wanted to watch some tube last night when I got in, and just didn't have the energy, had to just flop instead. But soon...

!


b

Joikd,
I pulled the front screen of my ws-65813, all this shimming stuff has me willing to give it a try.

Did you pull the top half of your set to raise your CRT cage? With the top half on, it looks like no clearance with the cage frame and black styro from the top half. Just wondering how you slipped your shims in there. Looks like 3 inches will put your crt cage even with where the styro flares out to the screen.

I dont want to trim any of the stryo off, I think it helps with internal reflections, I dont really get any halo-ing in dark scene with this set.

I can't see how, if I lift the top half of the set, how I can put it back on once the CRT cage has been raised, esp 3inches. because the top half has to be dropped in then slid horz to get the top even with the bottom. How did you do it?

I looked down inside my crt to look for burn in around the perimeter to see if I would have problems expanding the image out. Couldn't see much of anything even with a bright flashlight. I guess I'll be ok, when I bought the set used it had 5% overscan around all sides.

I guess it wouldn't be safe healthwise to turn the set on and look into the CRT to check for burn-in around the edges, with x-ray warnings on the lens barrels? Plus I need a way to keep the front screen power button wiring harness etc connected with the screen removed to power it up

Angelo,

There might be a better way, but here's how I did it:

1. Remove the front panel, and free up some slack by removing the wires from those white ties (I think there were two--one by red & one by blue). The slack is needed when you raise the assembly.
2. If you're doing 3 inches, use pliers to slightly bend the side of the metal tray (bulkhead?) in on both sides--only needed towards the front corner on each side. Before you do this, you may want to try lifting the assembly first, and see exactly where it hits. I didn't trim any styro.
3. It might be easier to remove the top half, but I think I just removed the screen (I don't have the protective screen, so removing the screen is much easier than it was before).
4. My set of four wood blocks ended up being four .75" pieces each that I glued together, which I'm glad I did because it would have been too hard to try to stack pieces on top of each other for the two corners near the front (hands do not fit up in there). Plus, individual pieces would be hard to control, and keep them from moving around.
5. I needed another person to put the shims (from the back) in while I lifted the tray (from the front). This is after removing the four screws that hold the assembly in place. Once the screws are removed, there is a nub? on each side that keeps the tray from slipping off. Lifting the tray is awkward--I used a thick allen wrench and hooked it through the hole in the side of the tray towards the front, and the other hand lifted the tray from the back. Doing one side at a time, it went like this: lift one side--the other side stays locked with its nub; place first block just far enough in, so that it is on the angled section just far enough in that the end of the block touches the "corner" where the angled section goes horizontal (it acts like a brake, and holds the block); do the same for the other side, then immediately push that second block all the way to the front corner (used two wooden paint stirrers to guide it up, and kept it tight on the edge)--so, at this point you have two blocks in (on opposing corners); immediately slide the third block in place behind the second in the same angle-locked position as the first block; then do the same on the other side--guide the first block up into the corner, place fourth block in the angle-locked position. With all four blocks in, the assembly shouldn't really slide, but be careful. That's it for my helper--the rest I did on my own.
6. I used two 4" #10 wood screws from Home Depot (one on each side towards the back), and secured the assembly again. The back shims don't really move and are easy to get to if they do, but the front shims are a pain to get to if they move too far (they kept turning on me) Once the assembly is raised, you can reach in with your fingers from the front and reach the front shims--but, not much. So, I used my fingers and slid the two front shims back down towards the back slightly, then used a couple of wood screws through the front (same holes as the back 4" #10 screws--just on the front side). This keeps the blocks from slipping off, and allows me to adjust them if they rotate. Ideally, you would want to pre-drill holes through the two front blocks, and use them same 4" #10 screws on the front--that would both secure the shims & the assembly. But, I didn't want to pull everything back out to do this--plus I don't think it's really necessary.
7. Using two solid, nickel? door stops (Home Depot) that have rubber on both sides, I ended up barely sliding in the tips in between the tray and the front shims. They are angled & not straight because there isn't enough room to be straight without raising the tray too much. I used metal door stops because I thought that the rubber ones might flex over time, and move the picture.

That seems like a lot, but it's really not. I'm not handy at all (lucky I didn't lose any fingers sawing my blocks), so if I can do it, I'm sure you and everyone else can without too much difficulty.

Let me know if you have any more questions.

I actually like some overscan on say mitsubishis. Result is a bigger picture with less black bars. Only full screen content is the only real benifet. I would have been happy just keeping my lenses clean when i had my rp-crt.

I saw no need to lift the top half of my set off, to get this done, but have not seen the 65" version, so can't say for your set.



There are many layers of plastic between you and the CRTs, I would not worry about it. I had radiation therapy in '80 for Hodgkins Disease, at Stanford Hospital via linear accellerator, very high powered stuff, and learned that even plastic attenuates the Xrays, they have charted it out. I can't imagine that just looking in for a few moments at a time would cause any damage to ya. The warnings are for continuous use.

Your remote will operate your set just fine with the viewscreen wires disco'd. Its sensor is inside the optical cavity, and gets hit by the commands sent thru the viewscreen and then reflecting off the mirror, in normal use. Just remove the screen, then aim into the cavity and shoot the remote commands, to fire it up.

What you WON'T see is the indicator lamp on the frame going on, which of course IS disco'd, so give it a little time to come on, as usual...


b

Joikd,

Thanks for the detailed step by step. I have it printed out. Now that I think about it when I had the top half pulled the stryo was still in place around the bottom base. Now that I got your instructions it is much easier to visualise what to do.

I'm not sure the reason of step #7 with the door stops. Is this to reinforce your shim or to keep it from moving side to side?

Now in a prevous post to me awhile back you told me how you did your lens focus with string. Did you do it again this way. Just wondering, I did my focus by pulling the back cover, just afraid if I raise the cage 3 inches I might not be able to reach the top of the lens with my hand, due to clearance.

Again thanks!

Zues Your right that is a valid comment. Right now I am perfectly happy with what I am seeing. I don't want to have an mishap and lose everything. Thats why I have been asking alot of questions lately about shimming in the posts

Its just that when you shim, you can use a bigger portion of your CRT face which should net you a much more dense image. Just like holding a flashlight against a wall from 2 feet, move it in another foot and the projected beam fills less space, thats where being able to ajust your conv outward to fill the screen you use more of you Crt face area.

Mr. Bob, Thanks for the response about the x-ray info. I figured it wasnt a problem for what I want to do. Also thanks about being able to fire up the set with the remote, while the viewscreen wires are disconnected. Good to know!

The doorstops are only temporary, for setting the horizon angle and vertical centering of your image before tightening everything down. Once you have tightened everything down with the 4" screws/bolts, nothing's going ANYWHERE in there after that, and the doorstops can be removed.


b

For the optical focusing, I highly recommend the Cantilever Technique once all is set in stone again, in there. No need to go in thru the back or use strings.

I use it every time, and nail it every time. I later delight on being able to study the grain of the film used to shoot movies.


b

BTW, if you change your centering of the images on any of your CRTs via the centering mag rings, this may change your astigmatism alignment, if your set has the astig mag ring set on the CRT neck. As such you may need to redo that alignment on each gun whose centering mag rings have been changed.

I have elected to not change that, instead shifting my r and b hor centering via the sm settings. This has placed them WAY outside normal parameters of staying near 50 or under, winding up somewhere around plus and minus 230 respectively.

But it has not caused any ripples that I can see in the linearity of the images involved, so I think I'll keep it that way. On the Pioneer Elites, if you do lots of this kind of shifting, or go outside normal parameters too much, there is lots of curving BETWEEN the cursor points, and of course that is uncorrectable. On Mit's, the edges simply start to fold over or get non-straight when it gets too far away from center.

I have seen none of this on mine, and I do look for that sort of thing, so I am going to keep my centering mags right where they are...



b

Ah, I misunderstood. So, that means I'll have to add a little (maybe a small piece of wooden paint stirrer) just to the shims on the front (high) side to raise that side up. Basically, the front shims will be slightly higher than the rear shims (I need to lower the picture). Correct? If that's the case, I can move both of my front shims all the way to the front corners, so I can add the front two 4" screws.

Mr. Bob, after shimming and doing the focus, I noticed what I think is a scheimpflug problem (even a little with green). So, I added washers. Green looks great. Red was slightly off to begin with, but no matter where I added washers (tried both sides), it made it worse--I ended up with both sides being equal, but way out of focus compared to the middle. So, back to no washers for red. Blue is killing me. The upper/left area was always slightly blurry. After shimming it's a little worse. But, I can't seem to correct it--I've been moving washers around in different combinations. If the upper/left is blurry for blue, what do I need to do with the blue lens? Which direction does it need to be "pointed" to? I just can't picture it in my mind. I should add that I can get the upper/left in focus with manaul focus adjustment, but then the rest of the picture is out of focus.

By the way, to avoid dust from geeting inside, should I tape the area where the lens housing is now lifted slightly do to the washers, and seal it off?

Thanks!

Mr Bob, I've tried your Cantilever Technique many times, but I just can't seem to rotate the lens with such small, precise movements (I would never have been able to be a surgeon). When I twist from a dead stop, sometimes I don't even feel that it's turning, and by the time I realize it, I've gone too far. You've also mentioned that you max out VHGT in JUNGLE temporarily while adjusting focus. I've been scared because of the warning in the service manual. I just want to confirm that it is okay for me to do this as long as I lower back to within the limits per the manual.

Angelo, I've given up the string techinique. Now I look through from the back while I'm adjusting, and my girlfriend looks from the front. Between both of us, it come out the same as the string method--just quicker and easier.

I didn't change any of the angles on mine, and don't see any need to, but will look into it next time I do some watching. Don't think any re-angling needs to be done, just moving the entire array forward or back until centered vertically and set using the doorstops, until screwed down permanently -


b

Have you remembered to put your optical lenses out of focus for the sch alignment on each lens? Make the 1/8" grid lines about an inch thick and the answers to what's thicker vs. what's thinner should leap out at you -


b

Have you marked your starting point on the lens barrel vs. the turret before starting, with a very thin line on both? That's how you know how tiny the increments need to be. And yes they are VERY tiny movements, which is why I use moving the screen in and out for verification, and not just moving the lens barrel in and out, which was the typical way before I came up with the CT.


No, I don't. It was suggested by others in the past and I tried it, but I have never really adopted that technique, haven't used it for years since I tried it back then just once or twice. I leave VHGT alone, and use 480i/p grid lines for my focusing. I watch for the shadow in between the 2 hor lines, plus the shadows between the hor dashes that form the vertical lines.



The Cantilever Technique is as accurate as accurate gets. I don't see why you are trying to find other ways of doing it, which are not anywhere near as simple and direct - and not always 100% effective, as the CT always is - as the CT!





b

I'm not understanding. When you say the "entire array", do you mean just the top section? During the shimming process are you moving the lower section that the upper part screws into? If not, I guess I don't see how the upper part can be moved foward or backward--if screwing it down I would think that there is only one position it can be in--otherwise the holes wouldn't line up, and it wouldn't screw in. What am I missing here?

By the time you have shimmed it by 3", there is a huge amount of space between the top and bottom of the 4" screws you use to finally solidify it. The "nub" that it originally fits/slips onto on each side in the assembly process for accurate centering purposes is worthless by the time it's been raised so high.

LOTS of slop room, forward and back and maybe even side to side.

That's why you need the wedge-shaped doorstops, for getting it completely right before cinching down on it. HD DVE overscan pattern is the best way I've found, for centering it accurately.

Use that to center things accurately BEFORE you do the shimming, before you uproot anything, so it will match up accurately afterwards too.


b

Mr Bob, I guess for me (other than my inability for fine movements), there is no way I can tell if I've made a difference unless I see the change in real-time. Looking in from the rear while making the adjustment is not very precise--I just do that to see if I'm going in the right direction. By the time I see where I'm at from the front, make the adjustment (either by swinging out the screen, or doing it from the back, then look at the picture again, I have no idea what changed unless there is a significant difference. I guess that's why you're the expert and get paid for your skills.

That's EXACTLY why I came up with the Cantilever Technique, all those years ago. I woulda said back then exactly the same thing as you're saying now!



The CT gets you that noticeable difference, WITHOUT changing the position of the lens barrel vs. its turret! It uses the screen position, in vs. out, to show you, and when you see the noticeable difference in each direction, that's what you judge by. When both noticeable differences, screen in vs. screen out, are symmetrical and equal - the image starts to go out of focus and becomes noticeable in each direction - you know that when you put the screen back at rest, equally spaced between the in and out offnesses, it will be in total focus.


b

Yes, I started with that, then refocused after adding the washers. What I can't seem to do (especially for blue) is get equal, unfocused line thickness (so, I guess that refocusing is a moot point)--they are slightly off. I just don't know how to arrange the washers--I'll keep trying different arrangements. I don't have a frame of reference to how close the sides should be to each other. I'm shooting for exact, but what is a real expectation of how close they should be to each other? After focusing, should I clearly see scanlines from corner to corner across the entire screen for all three colors (individually)?