After spending 8 hrs yesterday experimenting with all the information and advice given to all of us from the experts here on the forum, was able to get my ECP looking the best I've ever seen it. In fact, that after following Mike Newmans instructions for setting up an ECP, I can do a hard reset and have an image that's almost watchable (about 75% converged). So when I was done last night I thought, Thats it, thats all she's got. Wrong. I decided to try Guy Kuo's focus technique. Very time consuming, frustrating and worth every minute of it. About 1 1/2 hrs a piece for this partly because the tubes need to be cleaned off first or you may confuse dust on the face for phosphor grain. What this technique does is takes the guess work out and leave you with a stunning 3-D picture that you can't help but notice. The first 15 seconds of Cats and Dogs where the camera pans down through the trees made me feel as though I was floating down there myself. :cool:

Thank's to All

Chip S.

Where did you find Guy's focus instructions...I just tried to do a search but am having a problem loading anything but the first page of his posts.

no kidding spill the beans

I am also looking for top notch focus instruction... but when I do a search on the forum... all the links come up like this one

http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=63695&highlight=HOW+to+Focus+a+Runco%2FNEC

totally blank

I believe this (http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=94477&highlight=hocus) is what you're looking for.

Steve

Ok, I read the re-post of Guy's post (and I want *my* ECP to look it's best). My only question is that at one point, Guy says to show the "EM pattern". What's that?

Cary

The "EM" pattern is Sony's internal focus pattern which is looks like the letters E & M.

I'm going to combine a few of my focus and astig posts into a single post here.

CRT PROJECTOR FOCUS & MECHANICAL AIM BASICS (updated 12/25/2004)

Guy Kuo

Ovation Multimedia, Inc. - Home of

Avia PRO
AVIA Guide to Home Theater DVD
Sound & Vision's Home Theater Tune-up DVD


Focusing and aiming a CRT projector is a daunting task. It involves two projection systems which operate in series - optical and beam focus. Problems in one system make it difficult to see problems in the other. As a result, first time owners are sometimes at a loss as to which system is the problem. Add to that the need to astigmate the electron beam and adjust lens flapping (Scheimpflug) and the novice CRT setup can fall far short of the projector's optimum.

Read through this document in its entirety before proceeding. At first, it will seem as though some steps are discussed in jumbled order. I have attempted to present this in sequence but one must perform tasks iteratively to achieve the final result. One revisits earlier steps because later steps make earlier ones easier to do more accurately.

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Equipment Recommended:

An external test pattern DVD such as AVIA or S&V HTT or a test signal generator provide the signals needed for alignment.

A good pair of binoculars which can focus at SHORT distances is very helpful for critically observing the effect of adjustments.

One roll of 3M brand blue easy release masking tape for marking the center of screen surface and edges. Do NOT substitute another brand of tape.

Tape measure to find center of each screen edge

Laser Pointer or CLEAN straight edge for finding screen center

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RASTER, IMAGE AREA AND INTERNAL TEST PATTERN CENTERING ON TUBE FACES

Centering of the image on the tube phosphor surface is done by centering the raster on tube phosphor and then centering of the actual image within the raster. You should begin by hooking up and displaying a video source.

Raster - The area of the tube phosphor that is painted by the electron beam.

Normally, only part of the raster is actually used to produce the image. The raster can be seen by peering through the lens after turning down contrast nearly all the way and then raising brightness to make the normally black raster light up. This makes the entire raster light up dimly. It may be necessary to open the left, right, top, and bottom blanking controls to allow visualization of the entire raster. Size of the raster is adjusted using vertical and horizontal size (aka amplitude) controls. The rasters are best kept small enough to ensure active video image is never extended beyond or near the phosphor edges. Keeping at least 7 to 10 mm of unused phosphor on all edges helps prevent the catastrophic tube failure that will occur if active image is projected beyond or too close to the phosphor edges. Since the raster is usually larger than the actual image area and it is actually the energy of the image area that can cause damage, some installers will allow the raster to extend beyond the edges while still maintaining image area within the safe portion of the phosphor.

When viewed on screen, the leftmost portion of the raster is drawn first after the electron beam completes horizontal retrace. Looking into the projection lens the orientation is backwards. During the first portion of the horizontal movement the beam has not settled completely and one may see some waviness in the image if the extreme left edge of the raster is used. Some installers will intentionally displace the raster slightly leftward so the active image is displayed on the later, more stable portion of the raster.

Centering the raster is performed by use of centering magnets on the CRT necks just behind the deflection yokes. The centering magnets are a pair of rings with small tab handles. By rotating the rings relative to each other and also around the neck of the tube one can shift the raster about the phosphor surface. Most projectors also have electronic static position controls for fine adjustment of the raster centering. It is best to use minimal electronic correction to reduce strain on the convergence circuitry. One can do so by centering the electronic controls prior to centering the raster with the centering magnets. On some projectors (such as NEC XG's), there are no centering magnets and raster centering is carried out purely with electronic controls for raster centering hidden in a service menu. Even on such machines it is reasonable to first center the user centering controls prior to setting the service menu raster centering controls.


Image Area - The portion of the raster which is actually used to display the video image

Within the raster, the active video image is displayed. The projector often has "position" or "image shift" controls which allow movement of the image within the raster. The name of this control varies from brand to brand. You can verify you have the correct control by making the raster visible and seeing if the image is moving about within the raster but the raster is not moving as you use the control. If raster moves as well as the picture, you are adjusting the raster position and not the image position within the raster.

Ideally, the image area is centered both vertically and horizontally on the phosphor surface. You can achieve this by first neutralizing the linearity controls and then centering the raster relative to the phosphor edges. Then center the image area within the raster edges. Once both are done, display a white field pattern from a calibration disc (AVIA, S&V Home Theater Tune-Up) and verify that the active is centered in the phosphor. We'll cover this in greater detail later.

BTW, Don't use an internal test pattern for checking centering as they are often not themselves centered relative to external signals unless you have also taken the steps described next in this note.

Internal Test Pattern Centering

Built in test pattern generators do not necessarily coincide with actual video signals in timing. They tend to be off center and not exactly scan locked to match a real signal. This means that making an internal test pattern look correct does not necessarily optimize the machine for a real signal. However, internal test patterns are handy and some machines like NEC's actually require you to set their timing relative to the video signal and convergence systems to prior to other geometry and convergence adjustments. If you have a machine which allows adjustment of internal test pattern timing, it is possible to center the internal test patterns to coincide with the center of actual video signals. This is much easier to do if mechanical gun aim has already been accomplished. In the next section, mechanical gun aim will be covered so skip forward and do that. Then set internal test pattern centering (phase) as described below.

For example, the phase control of NEC projectors MUST be set before geometry and convergence adjustments when creating a new input memory. The phase control changes the timing of the internal test pattern generator and also timing of the convergence system relative to the video signal. Since you have already centered the gun mechanical aim and centered the image on the screen and phosphor surfaces, adjusting phase to make the internal generator centered on screen also centers it with the video image center. Adjust phase to make the center vertical line of the internal generator centered left/right on screen. Then adjust phase to make the deflection blip centered around the center vertical line. The blip shows the centering of the convergence system. If it makes it easier for you, display the internal center cross pattern rather than the crosshatch while adjusting phase. Ignore the odd shape of the lines, just concentrate on the position of the middle of the center vertical line and the blip.

Since there is no control to shift the internal test pattern vertically, the only way to achieve vertical coincidence of the image and internal pattern centers is the image position control. Once that is done, you may need to readjust projector tilt to get things centered on screen. Going through all gains you the option of using either internal or external test patterns with good accuracy.

One should strive to keep the image centered within the phosphor surface and leave at least 7 to 10 mm of unused phosphor all around the active image. Mechanical aim of the guns is easier to do when the image and rasters are vertically and horizontally centered on the tube faces. Further fine tuning of raster and image centering can be performed as well as centering of the internal test pattern generator once gun aim is accomplished.

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MECHANICAL GUN AIM

If your projector has lens tilt rings, set them to factory spec for your projection distance before doing any aiming.

You must first mechanically aim the guns properly. Most CRT projectors have red and blue lens/CRT assemblies (aka gun assembly) capable of swinging left/right. Up/down mechanical aim is accomplished by altering projector tilt. These movements mechanically aim the center of all three guns so they converge at screen center. Typically four bolts accessible at the bottom edge of the gun assembly secure the gun. These are loosened to free the lens and gun assembly and allow left/right swing. Do NOT REMOVE all four screws. Merely loosen them. Check in your installation manual to verify which screws need to be loosened. Some projectors only have a few fixed swing angles which are secured by placing a locking screw through specific drill holes. Others allow infinitely variable convergence angle and are secured by placing the locking screw through an arc shaped slot instead of a hole. The green gun usually isn't adjustable left/right so getting the projector centered and square to the screen during mounting is vital.

The guns sometimes stick in their prior position even when the screws are loosened. Controlled pressure can free a gun, but never force the guns because a sudden give way motion could snap a tube neck. One method of producing controlled pressure is to place some fingers between the lenses and gradually form a fist. This allows considerable pressure to be exerted without risk of sudden excessive motion. Once freed, just point each gun exactly and lock them in position. How that is accomplished comes next.

Marking Screen Center

Mark the your projection screen's exact midpoint of each edge (top, bottom, left, right) with a triangle of 3M blue easy release tape. Then mark the exact center with a LIGHTLY applied triangle of the same tape. This tape, if left for less a few hours, should not mar a screen. At least it never has in my hands. I cannot say the same for other brands so I suggest no substitutes. Finding screen center can be accurately done using a laser pointer placed at one screen edge midpoint marker and bouncing the beam off the screen surface to make a spot at the opposing midpoint marker. If a laser is not available, a tape measure can suffice so long as care is take to avoid marking the screen with tape measure.

Aiming the Guns

The traditional method of setting mechanical aim is to display a center cross, center the cross in each phosphor and then swing the guns and tilt the projector to place the projected red, green, and blue crosses all at screen center. The problem with the traditional technique is the difficulty in judging when the center cross pattern is accurately centered on the phosphor. I prefer an alternative technique which is easier to visually judge ? centering using edges. Basically, this takes advantage of how easy it is to accurately judge evenness of the gap between test pattern edges and the phosphor edges.

Turn down contrast and display a white field pattern and shift the raster to make the edges of the pattern equidistant relative to the phosphor edges. Look into the lenses while doing this, not at the screen. You will need to do this for each gun. The pattern will be widest at the CRT bottom assuming ceiling mount. Adjust size and position left/right to assure the pattern is well clear of the phosphor edges and equally spaced from the edges at its greatest left and right extents. Adjust the pattern up/down to achieve even spacing for the top and bottom edges as well. Once that is done, the pattern is precisely centered left/right and top/bottom on the phosphor surface. All you need to then is mechanically aim the guns to project that centered pattern so its edges are centered relative to the projection screen.

Look at the top of the projection screen and examine the left/right relationship of the projected pattern edges and the screen edges. Swing the gun left/right to equalize the edge relationships. Don't worry if the red and blue guns are not yet the same width. Just make sure the edges are balanced left/right for each gun. Lock the CRT's into position. They are now precisely mechanically aimed left/right.

Next, pay attention to how the projected white field pattern is positioned vertically using just the green gun. You should have previously set the pattern so is centered up/down on the phosphor. Adjust projector tilt up/down to make the projected green white field edges equally balanced relative to top and bottom screen edges. Now for more explanation.

If you happen to know your center cross pattern is already precisely centered you can just use the center cross to aim the tubes. Unfortunately, the most accurate way I know of doing that is to pull the lenses off, center the cross on the phosphor while measuring with a ruler, then remounting the lenses. The white field pattern edge comparison method described above allows easy, accurate physical aim and centering on the phosphors without pulling the lenses. This also gives a subtle plus for the red and blue guns as I'll explain later.

I know this method seems backwards, but balancing the edges of a white field pattern against the edges of the phosphor and then the projected edges relative to the screen edges achieves precise mechanical aim in an easy manner. The advantage to this method is basically the difference between having someone mark the middle of a piece of paper without aid of a ruler vs aligning a slightly smaller piece of paper so it is uniformly spaced inside the larger piece of paper. The latter is easier to do accurately.

Consider the off center red and blue guns. If you aim the actual center of the phosphor of those tubes to project at the center of the screen, you'll note that the phosphor usage distribution is unequal left/right due to the throw angle. Graph it out and you will see that the farther half of the screen gets illuminated with a smaller area of phosphor. Ever notice how the side of the screen opposite the side of the gun is less well focused? This is part of the reason.

Centering a field pattern relative to the phosphor and then using those lit up edges to guide lens aim will actually place the red and blue guns so they are mechanically slightly off true center. The left lens ends up pointed slightly left of center and the right lens ends up slightly right of center. At first blush, this seems wrong, but this can actually be advantageous because it makes the raster usage, resolution, and illumination more uniform across the screen. Less horizontal linearity compensation and lens flapping are needed.

Now if you are a traditionalist and want the center of the phosphor actually aimed at the center of the screen, you can pull the lenses off, set the center cross with great precision and then use the projected center cross position to guide mechanical aim. This is the usual way things are done, but I present an alternative approach with some advantages.

You have now precisely aimed the gun assemblies. From now on, anything projected that appears centered on the screen is also appropriately centered on the phosphor.

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Note: Mechanical Aim is Not Scheimpflug (Lens Flapping)

Novices confuse the two, but mechanical aim is not the same as lens flapping (aka Scheimpflug). Mechanical aim of the CRT/lens assembly is akin to taking a telescope and physically pointing it at something. Lens flapping adjusts the mounting angle of the end lens without changing the direction the telescope is pointed. Lens flapping doesn't change the direction of aim (well just a little), but compensates for the planes of the screen and phosphor being non-parallel. If the lens were kept parallel to the phosphor surface, it would be impossible to focus throughout the screen at the same time. The flapping places the lens into a plane intermediate between those of the screen and phosphor and that makes global focus possible.



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ROUGH OPTICAL FOCUS

Now that mechanical aim of the guns has been done, it is time to do an initial, rough optical focus.

Display a crosshatch pattern. Adjust optical focus using the two knobs. The front most knob on the lens controls edge optical focus. The rear most knob adjusts center optical focus. Dial in center focus first. Then adjust the outer (front knob) focus to while watching the corner lines of the crosshatch flare inward and outward. Try to minimize flaring using the outer focus knob. Go back and forth between the two optical focus knobs to get both center in focus and outer edge minimally flared. Use of binoculars aids this process tremendously.

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ROUGH SCHEIMPFLUG (LENS FLAPPING)

Once rough optical focus is completed, you can perform lens flapping. The following is primarily for projectors which have continuously variable lens flapping. For projectors with lens flapping rings, simply set the lens rings per the installation manual specified settings for your projection distance.

Display a focus pattern. Look ONLY at the center of the top edge. Adjust center optical focus to make that edge sharpest. Note the position of the focus knob. Pay attention to the center of the bottom edge. Adjust lens center focus to make the bottom edge sharpest. Is the lens center focus control in the same position as when the top was sharpest? If so, vertical flapping is correct. If not, adjust vertical flapping using a wrench. Note the wrench position when the bottom edge is focused vs top edge. Set the vertical flapping to put the wrench in exactly halfway between the two positions. Horizontal flapping is performed in an analogous fashion paying attention to only the left and right edges.

Now go back and refine center and edge lens focus. Once that is done you should have the lenses in fair optical focus and flapping. Advanced owners may consider the 3 x 5 card technique fine focusing technique presented later in this document for even better optical focus and Scheimpflug.

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Phosphor Grain Optical Focus Technique for when the Electron Beam Has not been Focused Yet

Most people have difficulty deciding whether optical, beam or both kinds of focus problems are present, particularly if they have not already achieved good beam focus. Here is a trick for setting good optical focus without being confused by beam focus. You must have a good pair of binoculars which focus at a short distance to use this technique.

The phosphor surface of a CRT has an inherent grain pattern. Because this grain is visible and is exactly at the plane of light generation, one can use the grain to set optical focus independent of beam focus. A small piece of 3M easy release blue masking tape aids in keeping your eyes correctly focused on screen. Display a bright window pattern and intentionally defocus the electron beam to make the scan lines disappear. Adjust center optical focus while viewing the screen through binoculars. When optical focus is correct, the inherent grain pattern of the phosphor surface suddenly snaps into view. This is nearly impossible to see with naked eye, but binoculars make it readily evident.


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ELECTRON BEAM FOCUS

The electron beam focus system in a projector can be a simple one such as in an electrostatic system or a complex dynamically varied magnetic focus system. Sharp electron beam focus is easier if optical focus has already been done. Be sure to perform an adequate first optical focus prior to fine tuning beam focus.

You have also seen the word "astigmation" mentioned in regard to beam focus. Astigmation further shapes the electron focusing lens beyond regular focus controls and is important for achieving maximal beam focus. However, it should be fairly well set at the factory and new comers to CRT setup are best advised to avoid attempting CPC magnet astigmation adjustments until they are more familiar with projection CRT setup. For this reason I will cover astigmation last in this document even though it should actually be performed PRIOR to electron beam focusing adjustments.

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Focusing Lens Cap to Assist with Electron Beam focusing

The phosphor grain optical focusing technique largely eliminates the need for this trick, but I mention this for completeness. Some projectors come with a special lens cap having a central hole approx 1 inch in diameter. This is intended to reduce the aperture of the optical lens and allow examination of beam focus even when optical focus is not quite correct. Because the phosphor technique easily achieves good optical focus independent of beam focus, I recommend setting the optical focus using the phosphor grain technique rather than resorting to a focusing lens cap.

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Electrostatic Beam Focus

Electrostatically focused CRT projectors have their electron beam focus adjusted using variable resistors aka pots. These adjust the charge on the focus lens for each gun. Focus controls are often housed together and marked as focus for each color gun. On that same housing may also be "screen" controls which adjust G2 voltage. It is easy to inadvertently adjust the screen controls while attempting to adjust beam focus. I recommend that the novice cover screen controls with a taped on piece of cardboard to avoid accidental adjustment while attempting beam focus.

Check Beam Astigmation

Display a dot pattern on the projector. Work with only one gun on at a time and set contrast to moderately high level. Binoculars are once more useful in observing the effects of your adjustments. As you vary the focus pot setting, notice how the dots change between the overfocused and underfocused directions of focus adjustment.

The overfocused state changes the dots into a central bright core with a halo around it. Ideally the bright central core is exactly centered in the halo. Also the dots should move very little as focus is adjusted between over and underfocused states.

The underfocused state changes the dots into a uniformly lit blob. Ideally the blob is perfectly circular in shape at screen center. It is normal for some deformation to be present at screen periphery.

If you find the bright core off center, the blob isn't circular at screen center, or the dots move as you adjust focus, astigmation for that gun needs to be corrected. That is done using the CPC astigmation magnets on the neck of each gun. CPC magnet adjustments should only be handled by a technician or very advanced user. Great caution is required due to risk of electrical shock, death, and equipment damage. Novices should enlist the aid of a technician if astigmation problems are noted on an electrostatically focused machine. On electromagnetically focused machines, there are often safe user accessible astigmation controls, suitable for the non-technician.

Once correct astigmation is verified (or you have decided to live temporarily with poor astigmation), proceed with the actual focusing of the guns. On an electrostatic machine it is simple.

a. Display a fine detail focus pattern or a dot hatch pattern . Set contrast to a medium level.

b. View only one gun at a time and adjust that gun's focus pot for best overall focus. It is often impossible to achieve perfect beam focus throughout the entire screen. The screen edges are particularly problematic. Should that be the case, weigh the screen center as most important for your compromise setting. That is where most film material will be sharply focused.

The blue gun electorn beam is usually left slightly underfocused to allow better grayscale tracking at higher light output levels. If you have light metering capability, that means underfocusing the blue gun enough to increase blue light output by about 20% over the fully focused state. Note that this does not mean the blue gun OPTICAL focus should be left blurred. Just the electron beam focus! They are not the same.

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Electromagnetically Focused Projectors

EM focused projectors populate the pinnacle of projection CRT technology. These machines use a magnetic coil to focus their electron beams. This is often combined with a system for dynamically varying focus to achieve good center and edge focus. (This is also done on some electrostatic machines, but not with adjustability) The EM focused projector also usually has some form of dynamic astigmation controls to refine beam spot shape throughout the screen. These extra dynamic focus and astigmation controls allow very fine focus compared to electrostatic units, but more controls means greater effort to achieve final results. EM focus also induces some spiral geometry distortions which need to be counteracted. The novice can do it successfully, but more work is needed to get everything in order.

Fore and aft sliding of the focus coil and rotation of the dynamic astigmation coils are not covered in this document. Those are maneuvers safest left to experience hands.

EM focused projector typically include a remote operable control control for overall (aka center) beam focus. This is analogous to the focus pot in an electrostatic focused machine. An EM focused machine also usually provides additional controls for fine tuning beam focus at the image edges, corners or screen zones. These extra controls allow better edge to edge beam focus than just a fixed single focus control setting.

The EM focused machine also adds a mechanism for dynamically correcting beam astigmation for each portion of the image. Dynamic astigmation refines overall beam focus beyond that achievable with just static CPC magnet astigmation. Again a control is supplied for adjusting overall astigmation (center of screen usually) and other controls for each edge, corner or zone of the screen.


Check Static Beam Astigmation

The machine will usually have some sort of CPC magnet assembly for rough static adjustment of beam astigmation. If the CPC magnets are properly set, the dynamic astigmation system won't have to work as hard to achieve good astigmation. For this reason, it is a good idea to verify and adjust the CPC magnets are properly set by neutralizing all the dynamic adjustments and then checking static beam astigmation. If the underlying static astigmation is flawed, the CPC magnets should be corrected prior to performing dynamic astigmation. The complete set of CPC magnets may not be present in a EM focused machine. Consult your service manual. Once static astigmation is done as well as possible with the CPC magnets, fine tune with the dynamic astigmation system.

Set all dynamic astigmation controls to neutral to eliminate the effects of the dynamic astigmation system.

Display a dot pattern on the projector. Work with only one gun on at a time and set contrast to moderately high level. Binoculars are once more useful in observing the effects of your adjustments.

As you vary the center EM focus setting, notice how the dots change between the overfocused and underfocused directions of focus adjustment.

The overfocused state changes the dots into a central bright core with a halo around it. Ideally the bright central core is exactly centered in the halo. Also the dots should move very little as focus is adjusted between over and underfocused states.

The underfocused state changes the dots into a uniformly lit blob. Ideally the blob is perfectly circular in shape at screen center. It is normal for some deformation to be present at screen periphery.

If you find the bright core off center, the blob isn't circular at screen center, or the dots move as you adjust center beam focus, astigmation for that gun needs to be corrected. That is done using the CPC astigmation magnets on the neck of each gun. CPC magnet adjustments should only be handled by a technician or very advanced user. Great caution is required due to risk of electrical shock, death, and equipment damage. Novices should enlist the aid of a technician if astigmation problems are noted on an electrostatically focused machine.


Dynamic Astigmation

Once static astigmation has been adjusted with the CPC magnets, one can proceed with dynamic astigmation. Some projectors will automatically underfocus and overfocus the electron beam appropriately when astimation controls are engaged. If yours does not do so, manually set beam focus to be underfocused or overfocused as needed. See the later section on CPC Astigmation for details of over vs underfocused beams with regard to astigmation.

Display a dot pattern and set contrast moderately high.

Start with all astigmation controls neutralized (center, all edges, corners, or all zones).

Adjust center astigmation skew and height controls to make the center blob circular. The machine may also have dynamic equivalents of the 2 pole adjustment. Adjust that to make the central spot centered in its halo. The actually set of dynamic astigmation controls vary from model to model, but the sequence is to perfect the center astigmation first. Then do the edges and finally corners of the screen. Zones interact so go back and fine tune when done the first time.

EM Beam Focus

Once astigmation is completed, electron beam focus can be done while viewing a fine crosshatch or focus pattern. Again, start by neutralizing focus controls for center, edges, corners or all zones. Focus the center of the screen first. Then do each edge and finally the corners. This particular order allows the interaction of the edge controls to do some of the corner correction before using any corner adjustments. Once more, recheck overall beam focus and retouch as needed.

The goal of adjusting beam focus is not only to minimize electron spot size but also reduce the flare around the spot as much as possible. Any flaring will cause edge transitions to appear soft. You will create an overall sharper looking image by accepting a slightly larger spot size if doing so eliminates the flare. Overfocus the beam and then slowly back off the control to allow the flare to diminish. Leave the control at the point at which flaring just disappears. You may need to perform this adjustment with contrast turned up enough to show the flaring. This optimizes the projector for best sharpness but not necessarily best resolution. The dot size may end up slightly larger and reduce resolution, but the increased sharpness will usually make the overall image look better defined.

This concludes beam focusing for EM projectors. I have condensed the process. The reader will best find the particular controls for his machine in the service and setup manual for the machine.


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3 X 5 CARD OPTICAL FOCUS TECHNIQUE

At this point in the process, both beam and optical focus should be excellent, but further refinement is sometimes possible.

Use a plain white 3 x 5 card for finding the exact focal distance of the projector. Do this by moving the card fore and aft in front of your screen to see at where a fine focus pattern is best in focus. If it is already exactly at the screen surface plane throughout the screen, then you are done. If it is more than 1 cm in front of or behind the screen do the following. And yes, this will temporarily undo the hard work done getting the phoshor grain sharp.

Display a fine detail focus pattern (internal focus pattern or S&V Home Theater Tune-Up) and intentionally overfocus the optics (rear lens control) so that the center is best optically focused about 2 cm short of the screen. This is in the direction that extends the lens barrel forward. Bringing the focal plane slightly short of the screen lets you more easily examine the focal distances throughout the image area. Check the focal distance for each screen edge by moving the 3 x 5 card back and forth in front of the screen. You'll be able to see very accurately the distance at which things are best focused on the 3 x 5 card. Check if the distances are uneven between left/right (indicating a horizontal lens flapping error) and top/bottom (indicating a vertical lens flapping problem). Fine tune lens flapping to make the focal distances for top = bottom, and left = right. This is the time to fine tune lens flapping rings. The 3 x 5 card check is so precise that you'll notice the flapping changes caused by uneven tension on the lens mounting screws.

Next, pay attention to how the left and right edge distances compare to the distance at screen center. They should be about equal between center and edges. If not, slightly adjust the inner and outer optical focus to bring both the edges and center to focus about 2 cm in front of the screen. Notice that I don't have you check the screen corners. That is because there will almost always be a difference in the extreme corners and center and using the left/right edges gives a good compromise which preserves the central focus where the video image is going to be sharpest portion of a movie frame anyway.

At this point the optics are perfectly balanced in terms of Scheimpflug and inner vs outer lens focus. The next step is to shift the entire optical plane back onto the screen surface. Make tiny movements of the rear lens focus knob while repeatedly checking the optical focus position with the 3 x 5 card. One thing to consider is that you probably did all this with the projectors lens hood off and the lenses are a little cooler than normal. As the lenses warm up, their index of refraction decreases, the lens mounts expand, and the focal plane can move slightly inward or outward. You should recheck the focal plane when the optics reach normal operating temperature an hour or so after the lens hood and hushbox are closed. Also, recheck 24 hours later and compensate for mechanical settling.

If you use the 3 x 5 card for final optical focus, you'll note that it is so sensitive an indicator that even the slight shift of the lens while tightening the focus knobs will be detectable. Focusing a projector is an iterative process in which improvement in either optical or beam focus enable finer observation and adjustment of the other focus system. Patient and diligent technique is needed to achieve maximal sharpness of both optical and beam focus systems. Expect a great deal of exercise moving between screen and projector using this technique.

Perfected optical focus means that even better beam focus may be possible. Revisit beam focus and fine tune as appropriate.

Only AFTER both optical and beam focus are perfected should you do final work on geometry and convergence can proceed. Otherwise, geometry and convergences changes wrought by focus adjustments will upset a hard gained geometry and convergence setup.

Speaking of which, the next steps in projector setup would be

Rough geometry and convergence
Grayscale calibration (with possible blue gun defocusing)
Final geometry and convergence

Those next steps are not discussed in this article.



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------------- Advanced Setup Technicians Only ------------------

CPC Magnet Adjustment of Beam Astigmation

Warning!!!!! Novices and non-technicians are warned to avoid performing astigmation CPC magnet adjustments. Adjustment of CPC magnets should ONLY done by advanced setup personnel. Improper technique will render focus impossible. High voltage shock and tube neck fragility are also significant hazards during CPC magnet adjustment!!!!

Electron beam focusing lenses are not perfectly uniform. Also, the direction of the earth's magnetic field can cause the beam to enter the lens off center. Astigmation of the beam fine tunes the lens uniformity and centers the beam as it enters the lens. This allows the beam lens to create a small electron spot with minimal flaring. Poor astigmation can make good electron beam focus impossible.

Static electron beam astigmation is carried out using CPC magnets (called Color Purity Control for historical reasons) on the tube neck and/or electronic astigmation controls. If both CPC magnets and electronic "dynamic" astigmation controls are present, it is best to let the CPC magnets do most of the work and have the electronic astigmation system merely fine tune the effects. One must neutralize the electronic astigmation controls prior to adjusting CPC magnets.

CPC magnets are arranged as pairs of rings about the end of tube neck near the socketed drive board. They should not be confused by the much more forward raster centering magnets just behind the deflection yoke. Projectors don't always have the full set of 2, 4, and 6 pole CPC magnets. CPC magnet assemblies vary in appearance and mechanical design. Sometimes the ring pairs have a small knob allowing one to adjust the angle between the two rings of a pair. More often one merely sees tabs with which to manipulate the rings. The CPC have 2, 4, or 6 magnetic poles, but don't confuse that with the number tabs on the rings. One cannot actually see the poles. By varying the angle between the two rings of a pair (moving tabs in opposite directions or twisting a little knob) one varies the intensity of the effect. Rotating a pair about the axis of the tube neck (moving tabs in same direction or twisting little knob in opposite direction) changes the directionality of the effect. If all three sets of CPC magnets are present, the rearmost is the 2 pole (centering). The middle is the 4 pole (ovalness). And the most anterior (if present) is either non-functional or a 6 pole correction (triangularity).

I'll reiterate since this seems to confuse some people....

Intensity: The amount of effect that a magnet ring pair creates. For instance if you consider the two pole magnet pair, you can make the rings cancel each other out or augment each other by varying the rotation of the two rings relative to each other.

Directionality: The orientation of the net magnetic effect. If you spin a ring pair TOGETHER around the tube neck you spin the direction in which the poles affect the electron beam. Notice that this minimally changes how the poles cancel or reinforce each other. Spinning the pair together merely lets you vary the direction in which that magnet ring pair squeezes or expandes the beam.

Spinning a pair together changes the direction of the effect, but making the two rings of a pair spin in opposite directions changes the amount of their effect.


Because the factory performs CPC magnet alignment, shipping can shift controls, and end users are not expected to make these adjustments, the CPC magnets are usually held in place with some silicone adhesive. This must be removed carefully. Very cautious picking at the adhesive with fingers will usually free the controls. Do not mechanically stress the tube necks!

Again, neutralize all electronic astigmation controls prior to working with CPC magnets. On projectors which lack separate electronic astigmation controls, perform CPC and electronic astigmation while the highest scan frequency to be used is displayed.

I assume you know how to change the electron beam focus and don't get that confused with optical focusing.

The 4 Pole (middle) CPC magnets affects ovalness of the electron beam lens. Adjust this while displaying a dot pattern with contrast set moderately high. Intentionally UNDER focus the electron beam making the dots into uniform blobs. Adjust the 4 pole magnets to make the center blob as perfectly circular as possible. Physically walk up to the screen to judge shape. Turning the small knob or moving adjustment tabs in opposite directions alters the amount of ovalness. Spinning the 4 pole rings around the axis of the tube neck changes the direction of the ovalness axis.

The 2 Pole (rear) CPC magnets centers the electron beam in the electron beam lens. Adjust this while displaying a dot pattern while contrast is moderately high. Intentionally OVER focus the electron beam making the dots into a flare with a bright central core. Turning the small knob or moving adjustment tabs in opposite directions alters the amount of deflection. Spinning the 2 pole rings around the axis of the tube neck changes the direction of deflection. Make the bright core centered in the flare.

The 6 Pole adjustment is also done with the dots pattern in under focus. If the 6 pole works (it may not do anything) it creates a triangular astigmation change. Use it to correct any residual triangularity which you could not correct using the 4 pole.

Go back and forth between the 2 and 4 pole adjustments to get things right. As a final check, carefully watch the dots as you go from under to over focused. The dots should stay almost motionless as you vary the beam focus. If they move, redo the 2 pole adjustment.

Once CPC magnets are set, fine tune using electronic astigmation if available.

You will have to redo raster centering after adjusting the CPC magnets. If working on the blue gun, you'll probably want to leave the electron gun underfocused enough to make its light output measure about 20% higher than its fully focused state to improve grayscale tracking at higher light output.

Guy, as always, thank you VERY much for your time and expertise. The information you share is priceless.

Cary

I wonder how many people have raided their wives recipe file cards to work on their projectors;) I did. Thank's Guy.

Chip S.

Hello

Sorry for your NEC, it's really sad!

And thank you very much for your excellent post !!!


regards

Bruno

Guy,
In your EXCELLENT post, you discuss astigmatism adjustments in detail. You mention that projectors have either 2,4, or 6 rings for adjustment.
In my Sony G70, I believe there are only two rings. If I understand your discussion correctly, then these two rings must be centering rings only? In other words, adjustment of these rings will affect only centering and not focus quality. Is this correct?
If the above is correct, it would seem that the only MECHANICAL focus adjustments on the G70 would be the optical lens focusing and the flapping adjustments. All other focusing would be the magnetic focusing per the manual, and of course, your suggested techniques.
Does the above sound correct?

Thank you again, for all of the time you devote to this forum.

Ray Kawal
Sequim, WA

Originally posted by Guy Kuo
I have combined some information here from several of my postings to create a more unified document.
.

Thanks Guy. This is awesome.

Next time I move the PJ/screen, I'll use these techniques.

The single CPC magnet ring pair on the neck is a 4 pole. It is used to set the beam shape to be round while the electronic astigmation AQP, ADP are neutral. (Thanks to Steve Smith for verifying this)

This does point out one problem with discussing CPC and raster centering magnets. Not all projectors have all the magnets. Raster centering magnets are right behind the yoke but are sometimes not present. The same with CPC magnets which are near the socket end of the neck. They aren't always all there. Sometimes the controls are solely in the electronic domain rather than mechanical controls. The service manual might not even match what is physically present.

I hope that things make more sense with all the info gathered together into a document which can more or less be followed in sequence. I know it is a long procedure, but I think it's worth the effort.


[edit - paragraph moved to unified post]

"Incidentally, if the projector does not have separate electronic astigmation memories for each scan frequency, do the CPC adjustments while the highest input frequency is being displayed."

Yep, very important point.

KUDOS!

Actually, I meant the full astig (both CPC and electronic) at the highest freq. I have updated the main post to reflect that point and clarify a few things.

Even if you are not moving your projector or screen, go ahead and examine the focal plane using the 3 x 5 card without first changing the lens settings. The "give" of the screen fabric will be enough to examine where the focal plane is at screen center. The edges are harder to test without pulling the optical plane out in front of the screen. If the screen is a drop screen, then it's easy to check things by moving the fabric itself.

Hello,

Thanks for the great post.

I'm confused about step 1. You refer to the mechanical aiming of the guns and raster centering. I can't figure out what you mean. Are you refering to using the projector's shift controls to center the raster on the tube face? This wouldn't be a mechanical adjustment. Are you talking about moving the tubes themselves? How would this affect the raster position?

You also mention using a white field instead of the crosshair patterns because the internal pattern may be off-center. I think you may be refering to an internal pattern such as the warm up screen on the Sony 12xx series since this pattern is suppposed to utilize the entire face. If not, how is that step done for people without such a pattern? The remove the lens method?

If the rater centering is done like you described than it's nessasary to shim the lenses (unless they are very adjustable) to center the Red and Blue to the Greeen after the proceedure is done. I would rather stick with the factory shims and use the electronic controls to center the images at least for now so does that make the mechanical aiming a step to skip?

Thanks Very Much,

Brian

I'm talking about mechanically aiming the gun/lens assemblies so their optical centers are aimed right at the center of the screen, not simply moving the rasters about the surface of tubes that aren't actually mechanically aimed correctly.

You can skip steps, but the overall stability and precision of the setup is compromised.

HI,

Thanks for the reply. I don't really want to skip steps, I just was trying to understand the instructions fully.

My current understanding is you can use shift/zone controls to place the centercross pattern on the exact tube center then mechanically adjust the tube/lens assemblies to place this correctly on the screen.

Thanks again for the informative post.

-Brian

Guy,

What resolution do you generally run on your G-70??

Terry

The main posting has been updated to explain why the aiming sequence seems backwards.

My own unit is actually an NEC XG135LC from AV Science, not a G70. I run it primarily at 960 lines on a variable height 80 inch wide screen. The equivalent on a 16:9 would be 720 lines. The scaler I use (Faroudja DVP-3000) does my AR switching so I only need a single setup for NTSC.

Great Info Guy!!!
Thanks for taking the time to write this up nice and neat :)

I've been recently asked about this......

Mechanical aim is not the same as lens flapping (aka Scheimpflug). Mechanical aim of the CRT/lens assembly is the same as taking a telescope and physically pointing it at something. Lens flapping is adjusting the mounting angle of the end lens without changing where the telesope is pointed.

The red and blue guns of a CRT projector have mounting screws which when loosened allow the two outer guns to swing left/right. The central green gun usually isn't adjustable left/right (another reason to be very accurate when mounting the projector) Up/down mechanical aim is accomplished by altering projector tilt.

Lens flapping doesn't change the direction of aim (by much anyway), but compensates for the planes of the screen and phosphor not being parallel. The flapping places the lens into a plane which is intermediate between those of the screen and phosphor so the entire surface can come into focuse simultaneously.

(info also added to main focus posting)

Hey Guy.

I've been collecting your previous focusing tips and have applied them quite successfully to *rear* projector (well, all but mechanical aiming and lens flapping, which are the only ones that don't apply to my RPTV). Nice to seem them all consolidated and organized! The only trouble I've ever had is with the 2-pole CPC adjustment. On my RPTV, regardless of contrast level, the core and flare are just not distinct enough to effectively center the core within the flare. Maybe this is due to the short throw distances in a RPTV?

I've done the whole focusing procedure you describe above several times very successfully, except for the 2-pole adjustment, where I've always had to resort to working backwards, ie. searching (almost randomly) for some position that minimized dot movement when rotating the focus VR through it's range. But last week I downloaded a service manual from some other manufacturer and found a simple 2-pole method that worked perfectly for me, and finally allowed me to achieve *no* dot movement instead of settling for just minimal dot movement.

I marked the exact center of my screen and then used AVIA's center cross pattern, which has a convenient little dot right at the cross intersection. Then I just went back and forth b/t the 2-poles and centering magnets, using the centering magnets to center the dot in the extreme underfocused state and the 2-poles to center the dot at extreme overfocus. After only a few iterations of this I had a nice dots pattern with absolutely no movement at all throughout the focus extremes. Do you have any comments about this method?

Also, one thing I've always wondered: I have 6-pole magnets on my yokes but they are non-functional according to Toshiba tech support. OK, how can the 6-pole magnet pair be placed on the yoke and yet still be non-functional? Is there some other yoke component required somewhere to make them functional?


Thanks,

Steve (not to be confused w/other Steve Smith (Advanced Member) I see posting above...)

I think your method for setting the two pole should be fine if you are able to get zero motion with focus changes. It sounds from your description that you may be doing this on an RPTV with the screen mounted on the television. You will have an easier time seeing the core and flare if you take the screen off and look directly into the lenses of the CRT's. Give it a try. It is easier to set 2 pole if you can observe the core and flare.

The 6 pole magnets on the set cannot have zero effect unless they are physically present but not magnetized. In effect, unmagnetized poles would be duds.

Ah ha. Yes, I was doing astig & alignment w/the screen on. With one hand on the magnets and the other at the focus VR, I'm starting at the screen from like 8" away, where everything is going to be fuzzy to say to the least.

One other question about non-magnetized 6-poles: if they're non-functional, why do they bother to even put them on the yokes? The CRT manufacturer just puts them on by default on all their CRT's, and then the set manufacturer chooses whether or not to magnetize them?

Steve

The poles would have to be magnetized before the CPC assemblies were put together, so I'd bet they were ordered as duds and simply never magnetized. The triangular correction is probably one less thing to set up during display assembly at the factory. Less setup time means less cost.

I'd bet this is why we are seeing sets now which have a single scan frequency and use a scaler to convert everything to the same scan frequency instead of changing raster sizes and scan frequencies. You only need your workers to set up one convergence memory at the factory. One just needs a built-in scaler good enough to satisfy J6P.

Well if I could magnetize them, I would. I don't mind one more thing to set up <g>.


One other question for you, Guy:

Can the phosphor grain focus technique work for RPTV's? I'm guessing that this surface grain will be far too fine to actually see through my frensel/lenticular screen stack?


Steve

The lenticular and fresnel layers on an RPTV do make for a fairly coars screen compared to a good front projection fabric. Even Dalite's moderately speckled fabrics can interfere with seen the grain so no I don't think the phosphor grain method is as applicable to RPTV's. Better to use the "cantilever technique" by Mr. Bob. http://www.keohi.com/keohihdtv/index.htm

Just goes to show ya. Take a CRT owner who thinks he's got it right, tell him you know a way to make it better and I'll bet he will listen. I'm glad I did. Thank's Guy.

Chip S.:D

bump

Not an unusual amount of replies, but look at the number of hits.
I think I've created a monster...:D

Chip S.

I'll put up some quotes from his message and then ask my questions. At one point Guy says.....

"Do a rough beam and optical focus. Mark the exact screen center with a lightly applied triangle of 3M's blue easy release masking tape. *** do NOT substitute another brand tape here **** "

On my Sony 1272, I assume the optical focus is with the lenses (R1/R2, Etc) So what is beam focus and how is it done?

"Beam astigmation fine tunes the electron beam lens to create a uniform electron spot with with minimal flaring. Poor astigmation can make electron beam focus impossible."

I think I understand that astigmatism is adjusted with the 2 and 4 pole magnets. If this is the case then how is the electon beam focused?

"The CPC have 2, 4, or 6 magnetic poles, but don't confuse that with the number tabs on the rings. One cannot actually see the poles. By varying the angle between the two rings of a pair (moving tabs in opposite directions) one varies the intensity of the effect. Rotating a pair about the axis of the tube neck (moving tabs in same direction) changes the directionality of the effect. "

OK, I got this one, the 2 and 4 pole adjust the shape and intensity of the dot.

"The 4 Pole alters the ovalness of the electron beam lens. Adjust this while displaying a dot pattern while contrast is moderately high. Intentionally UNDER focus the electron beam making the dots into uniform blobs"

So to focus or under focus the electron beam I use the lenses? I'm really confused.

"Display a bright window pattern and intentionally defocus the electron beam to make the scan lines disappear. Adjust center optical focus while viewing the screen through binoculars. "

I think all of my questions have to do with the difference between optical focus (using the lenses I assume), adjusting the shape of the electron beam (known as astigmatism and adjusted with the 2 and 4 pole magnets), and then focusing this perfectly shaped dot. So how do I focus the dot? Is adjusting the 2 and 4 pole, also know as astigmatism the same as electron beam focus?

I think it is all of this new terminology thast is causing me such difficulty.

Thanks Guy for the great instructions, I'm just having trouble with the terms. I hope somone has a few minutes to explain this to someone new.

Hi Areno,

I'll try to answer some of your questions,

On my Sony 1272, I assume the optical focus is with the lenses (R1/R2, Etc) So what is beam focus and how is it done?
it's electric focus, the 3 pots under the 3 screen or G2 pots, on right side of your sony, at the right of remote

http://www.biggerhammer.net/mediaroom/1252q_images/1252q_screencontrol_electronicfocus.jpg

So to focus or under focus the electron beam I use the lenses? I'm really confused.
you have to focus and underfocus with electric focus, I quote an explanation of astig adjustment posted by Chuck Williams (not sure):

What you want to see here is while moving the electronic focus from
100-0 and back to 100 the dots have NO movement on the screen. If they
do, you need to adjust the back ring to get the minimum movement.

As mentioned above, display a dots pattern. Set dynamic astigmation
controls to center position. This allows you to set the magnets to do
most of the work and just fine tune later with the dynamic controls.
Binoculars are very handy but must be of large light gathering power.
You'll need to significantly increase contrast setting to above normal
to see things clearly during astigmation adjustment. Also work with one
gun at a time. Cut-off the other two. Once astigmation is complete,
don't forget to return contrast to normal before final beam
focusing.Turn
e-beam focus to max one direction then the other. In one direction
(underfocused)the dots will become large circular or oval blobs with
uniform
brightness within the blob. In the overfocused direction, the spots
will
have a central luminous portion and a dimmer halo. These both need to
be
examined when doing astigmation.

The 2 pole magnets are the rearmost of the shaper magnets. These are
used to center the electron beam in the middle of lens. Place the
system
into overfocus to show the central luminous point and surround halo.

The 2 pole magnets deflect the luminous point. Twist the knob to alter the
amount of deflection. Rotate the knob about the tube neck to alter the
angle of deflection.

If you use a center cross pattern instead of a dot pattern when
centering the e-beam it's easier to see when the beam is centered in
the lens.
A center cross shows up as fat lines with a central luminous line. Just
adjust the 2 pole magnets to make the luminous portion of the vertical
and horizontal lines centered within the fat linear halos. It's easier
to see than staring at a point with a halo.

The 4 pole magnets are frontmost of shapers. It is used to alter beam
shape to a circular shape. One sets the tube to underfocus and displays
a dot patter.

This turns the dots into a larger,uniform blob whose shape
is adjusted using the 4 pole magnets. Twisting the knob adjusts degree
of oblongation. Rotating the knob about the CRT neck alters the axis of
the effect. Make things as dead round as possible for the center
dot. Turn focus up and down and make sure things track correctly. You may need to
make some minor tweaks to the magnets to get things just right.


The astigmatism adjustent can seem difficult at first go but once you do one tube you will
easily do the other two. With a signal applied first call up the cross hatch pattern then
kill the red and green guns. Turn the blue pot SLIGHTLY counterclockwise to unfocus the gun
then adjust for beam centering with the neck rings. Then call up the dot pattern and turn
the blue pot clockwise past the sharp focus then agjust the other neck rings to get the
beam shape as round as you can. Then bring the pot back to focus and reset color bias to
get a white square.


Focus the dots as well as possible. Then go on to the next gun. When
all three guns are completed, you now have "static" astigmation
optimized and this means the dynamic astigmation system is under less stress.
Perform dynamic astigmation for each zone as well as beam focus.

Now that beam focus is optimized, it's time to recheck optical focus
for center, corner, and Schempflug (horizontal and vertical flapping)

You can check lens flapping by using the center lens focus (rear
wingnut). Display an inverse +pattern and adjust center focus to make
the
center of the top screen edge perfectly focused.Note the lens control
position. Next adjust the lens to make the center of the bottom screen
edge perfectly focused. Is it the same position. If yes, vertical lens
flapping is dead on. If the two positions are not identical, you need to
readjust vertical Scheimpflug (flapping). Similarly compare the perfect
focus positions for left vs right edge. Finish by adjusting center focus to
perfection and touching up the corners using corner focus (front
wingnut).



good luck Areno!!!

Regards

:D :D :D :-p

Bruno Lovisi

Perfect Bruno!, Thanks, I can't wait to get home to give this a try.

Bruno got it. Electron beam controls are done using the electron beam adjustment controls (beam focus, 2 & 4 pole magnets) and definitely not the optical focus controls on the lens.

I'll just add a caution to leave the screen potentiometers alone. They are so close to the beam focus controls that it's very easy to accidentally turn one of them. The unfortunate result is a badly maligned gray scale. Taping a piece of cardboard to cover the screen controls before you start may save you an unanticipated problem.

Thanks Guy! Things are really looking good now that I have worked through your focus steps. Thanks Again. Adam

Hi,

A few questions for Guy.

I've been reading your focusing tips, but I have a few questions. I'm running a BG808. First, how would you do your intial mechanical alignment of the crt's on a Barco? You said to use a white field. How does that work? I do have Avia. Or do you use the setup crosshairs on a Barco? Second when adjust the astig, do I follow the same procedure that you outlined for the Sony in the above posts? Do I have to rotate the pins on the magnets as described above, to set the astig or do I just have to rotate the magnets on the necks as someone said in another thread?

Thanks for your help!

DougK

If you want to follow the technique, then you'd use a field pattern from AVIA rather than the internal cross hair. The advantage of the field is that it is easier to see that the edges of the field are equally spaced relative to the CRT glass edges than seeing if the cross hair is in the center of the phosphor.

The astig magnets on your machine are handled using a combination of twisting the little knob to vary the amount of effect of the CPC magnets. You also twist the entire assembly around the axis of the tube neck to change the direction of the CPC magnet effects.

Time to do a bump. The only thing I'd add is that those with the S&V Home Theater Tune-up disc should go into the video calibration section's special test section. Try out the new Focus and Crosshatch patterns. Both are in single pixel resolution, the finest that can be encoded on DVD. That's double the resolution of what I created for AVIA.

The focus pattern is as fine as possible, but you should also check with your built-in focus pattern to see which works better for you.

The new crosshatch is specially colored so you can now perform convergence of all three colors without needing to turn off or cover any of them. It's now practical to directly converge blue on green instead of the old, indirect red on green then blue on red sequence.

Originally posted by Guy Kuo
The new crosshatch is specially colored so you can now perform convergence of all three colors without needing to turn off or cover any of them. It's now practical to directly converge blue on green instead of the old, indirect red on green then blue on red sequence.

Being somewhat colour-blind with regards to red and green I used to find calibrating Red against Green very difficult because green output is so bright compared to the red gun leaving me unable to see fine misconvergences due to my colour blindness. Inspired by the idea above of "specially colouring" the convergence cross-hatch, I tried a new approach to converging red on green, which simply involves lowering the green gain before converging, so that red is the brighter of the two colours; I am then clearly able to see the red lines scanning through the green lines and get perfect convergence. Same works for blue/green. Once done I restore the green gain to it's original setting.

Mark

Wow, look at the mileage this one's getting. I'm glad it's been so usefull to others. It worked great for me.

Chip S.

I guess this as a good of time as any to bump this back up to the front. As soon as I get my new setup remote from Curt and my Escalara back I'll be trying this focus setup again. I'll be taking down the ECP 3101 and replaceing it with a NEC 9PG plus. Can't wait no mo bye...

Chip S.

Guy,
first off, thank you for this guide, your information is as always priceless.
Now you mention that home theater tune-up DVD - where can we get it ?
Thanks
Oliver Klohs

Bump. Main posting updated and expanded. New crop of CRT owners on forum.

Oliver,
the best tune-up DVD manufactured is called AVIA. Not sure where you'll be able to get it, but it's a must have for the hobby.

I recommend it to everyone, it's very easy to use. You're not serious about HT until you own it.

Do a search on the internet for: Ovation Software or AVIA.

I only hope that on the next version you'll be allowed to bypass the intro.

Mike,

thanks for the tip, but I do already own Avia and VE and was hoping for something else Guy mentioned in this thread called S&V Home Theater Tune-up disc.

Oliver Klohs

Oliver, you can find it at Amazon if your local Fye or other video seller doesn't have HTT in stock.

Mike, just hit the menu button on your remote. The current AVIA disc already allows you to go immediately to the menues without forcing you to wait for the intro and copyright screens to display.

Thanks Guy,
I will order the HT tune-up today.
Oliver

Guy,

Would your great set of instructions change for me since the screen I plan to use is curved (horizontally only, not torus) like Alan Gouger's $200.00 curved screen thread? Please give me your opinion on this. Thanks!

-PGPfan

I don't think it would be materially different. You will be automatically compensating for the screen curvature as you go through the various focus steps.

"Home Theater Tune-up disc..."

Guy,
can you tell us more about this product?

Guy,
This is the first time I looked at this thread and it is very good, you explained it very well. One of the areas that gets overlooked is when you move the raster centering it also changes the astig.

The set up from the factory is based on the 100" diag 4:3 format ceiling front.

Because the average HT set up is a bit different this procedure does make an improvement to dial it in to your application, screen, freq and phase.

A helpfull hint on the XGs it to hit the SW S5502 switch on the HV PWB to assume high beam mode, this helps to see the core, (dont forget to shut it off, protruding) also in the astig defocus mode if you hit test/end button it will go to the actual display but remain in astig mode, I like to use a external H pattern black back raster and dial the flair in by looking at the H using the cursors to get the H perfect, you can see this flair "pull" in all directions if its not optimum.

I think the disc is "Sound & Vision Home Theater Tune-Up" Ovation Software. I got mine from Amazon, also has DD / DTS audio set up 5.1-6.1

Good piece of work here Guy. Doug

Just time to bump this again. We have the need for wisdom...

Chip S.

Doug wrote:
> One of the areas that gets overlooked is when you move the raster centering it also changes the astig. <

Does anyone have a complete chart or list of the chain of dependencies? I.e., which adjustments affect other settings? Some of these are unexpected, even to non-newbies.

- Tim

This post is priceless...stop the bumping and stick it at the top forever or better yet, let's start a Meta-Faq as is seen in the Home Theater PC part of this forum! People are always asking where to look so why not give them a list of posts for the beginner up to the expert!

I have already tried to start a post on the Horizontal Line Problem so all manifestations and solutions are combined in one post:

http://www.avsforum.com/avs-vb/showthread.php?threadid=152888&referrerid=22283

Let our forces combine and call Captain Pla.....no wait sorry...let's combine the knowledge already present on this forum and make it more easy for the newbie (which I still am myself) to find the way in the big CRT-forest.

Holy Moly!

What a great post, Guy!

Thanks!

What would happen if you totally remove the astig ring?

Would that damage the tube?

I have lots of problems focusing my blue tube - it's totally out of whack - I am not talking a little out of focus here - I'm talking totally unreadable.

So, I played with the astig ring like it's mentionned here, and I decided (probably wrongly) to remove the ring and see what kind of result I would get. The result I got is that the output of the tube is now very very faint (maybe 5% of what it was before) (even after I put the ring back)

Could the removal of the ring cause this problem?

Thanks!

Sylvain Dumas

Guy,

Just some additional tips.

Rather than using blue scotch masking tape, I use post-it notes. I cut a portion of the note that has the stick on it and a portion without the stick to allow easy removal. I choose a color of post-it as needed/desired

I also, after marking the middle of each edge, place thin, black fishing line as horizontal and vertical center lines. The fishing line than cotton string is better as it does not stretch. The horizontal line must be tight as there will be some droop in the middle. I also make a diagonal from each corner. These should be tight as well. All should meet at the center if the screen is properly square. I then use a level to see if the horizontal and vertical lines are true (assuming the screen is true).

Finally, another way for finding center is to take a string and fold it in half. Tie a knot at the center point with a small loop in it. Now from the center point, make each side of the string identical in length. The length will depend upon the use. Attach each end to the left and right sides at the middle point. Hold the center point and pull it tight. The center point of the string (when adjusted to the needed length will lie on 2 center points (raising the V high and low of center) of the vertical string. If you make it long, it should be dead center on your projector's center tube's line. Do a point in the front and back of the projector's centerline to guarantee that it is pointed square with the screen.

In a similar fashion, connect to the V string to the top and bottom center's of the screen and check the horizontal string at two points.

Hope this helps,

Ira

Great post Ira.

Guy, this is probably the most usefull thread in the CRT section since I've been here (1999)
I re-print every time you up-date. I'm going to send you my A4 paper bill :D
Seriously usefull info. Superb.

^bump

I finally got the time to go all the way through Guy's procedure and all I can say is "WOW". My NEC 6PG is sharp, sharp, sharp. 720P is finally watchable, though still a little beyond this projector.

The only problem I have is now the dust on the back side of the lenses is in focus and very noticeable on a white field. I guess it is time for another cleaning.

:) :) :)

Hi

Bump the most important thread for a crt owner and a question :

- how do you mechanically aim guns on a sony vph-1270 ? add something to default spacer?

thank you Guy for ths wonderful thread!!!!

best regards

Bruno

Bruno

Yup, thats what I did. I also modified the PJ so I could adjust the lens flapping.

Check out: www.mooneyass.com for my manual/instructions

Wes

Hi Wes

Thank you for your answer, I've yet taken your setup file but I've not read how you modify crt's angle

You setup guide is great, thank you for this manual

I've already put default crt's spacer but I don't know how to aim more accuratly blue and red gun? could you give me some details?


Thank you very much

Best regards

Bruno

Bruno

Step 1: Pull green, red and blue lenses, place clear tape on crt face and mark exact center. Modify lens mounting as per my manual. Display cross hairs and center on all tubes. Remove tape and re-install lenses

Step 2: Ensure the PJ is perfectly square to screen and centered. Check out my recent post, do a seach for "ringo".

Step 3: Adjust the CRT spacers (use shims) on the R and B until the cross hairs overlap with the green. The red and blue should have very close to the same shiming, this'll tell you if you're square to the screen.

Step 4: everything else ;)

PM me if you have any other specific questions rather than clutter this wonderfull post with Sony PJ specific issues.

Wes

Guy
Is there a procedure for shimming your lenses if you have no schempflug (spelling I know)adjustment.
My Barco Data 808 does not have this adj and I need to shim the lenses but have no idea where to start and since everytime you rem and reinstall lenses a converge is req well you know.

Ennergeezer

If you check out my manual it has the instructions for a Sony but should apply to your Barco too.

http://www.mooneyass.com/Sony1270Q/

In the hopes that it does not get lost...

Chip S.

Chip - long ago I saved the entire contents of this post to both a pdf doc and printed copy (in case something should happen to the computer)... It's that! important!!!

Bump

I always see these permanent posts at the top of the page (that Hirez announcement thing that was up there forever), why can't this become one of those permanent posts.

Karim

Just a quick bumpity bump for someone who is looking for this thread.
Ask and you will receive.

Chip S.

In guys post he states "When viewed on screen, the leftmost portion of the raster is drawn first after the electron beam completes horizontal retrace. Looking into the projection lens the orientation is backwards. During the first portion of the horizontal movement the beam has not settled completely and one may see some waviness in the image if the extreme left edge of the raster is used. Some installers will intentionally displace the raster slightly leftward so the active image is displayed on the later, more stable portion of the raster. " I have my pj ceiling mounted does that mean I should move my raster to the left or the right? I wasn't sure if when I switched the pj to display from the ceiling if I changed the side the image starts on?

When you do the scan adapation inside the projector to invert the image for ceiling mount, the raster also inverts.

Thus Guy is correct in stating that the image is drawn from the top left of your screen to the bottom right, and the top left is the most unstable section because of the vertical retrace. (How could Guy be wrong? :D)

What changed is the area on your CRT faceplate where that left top edge is.

I think you want to move your raster to the left and up (when looking into the lens) to move the image area away from the "top left" edge of the raster since the image is drawn on the tube face upside down.

When you look in the lens this should be pretty obvious. Increase brightness until you can see the raster (don't forget to decrease contrast to its lowest setting so you don't blind yourself). The raster edge should shake a little on the vertical retrace, should be in the bottom right side of the CRT faceplate.

I havent tried this yet but it sure will come in handy when I get home tonight!!
Thanks Guys/Guy.
PBM

As Spearce said, the top left of the raster is the area of greatest instability. If you decide to move the active image area away from that part of the raster, what you end up doing is watching the screen and moving the raster centering so it moves leftward (and optionally upward) on the screen. This puts the active image into a more stable portion of the raster. Then you move the image within the raster to recenter it on the screen. This only works with machines that have a position control which slides the image within the raster independently of moving the raster. Also, be careful that you don't do this so much that the raster centering controls are working too hard.

Justin_P,
If you are wondering if your raster should start from the left or right, it is easy to check.
Just provide a source signal with text.
The raster will present a mirror image of the text (it will be backwards) if your rasters are set incorrectly.
This is assuming you are looking at the screen rather than into the lens.

Originally posted by spearce

I think you want to move your raster to the left and up (when looking into the lens) to move the image area away from the "top left" edge of the raster since the image is drawn on the tube face upside down.

When you look in the lens this should be pretty obvious. Increase brightness until you can see the raster (don't forget to decrease contrast to its lowest setting so you don't blind yourself). The raster edge should shake a little on the vertical retrace, should be in the bottom right side of the CRT faceplate.

Actually, I think that, to move an image down and right on your screen, you should, when looking into the lenses, move the raster up and right. Don't forget that the lenses flip the image in all directions, not only vertically. When you turn to face the PJ, you're adding a horizontal "flip" of your own. The two flips cancel.

For example, when I look into my M-8000's green lens, the 'no input signal' message is in the lower left corner, not the lower right. Interesting sidenote: the message is blackened in the red and blue CRTs relative to the red and blue "background", i.e., the rest of the tube faces.

Larry
www.fineelectricco.com

Thanks for the replys I think I am clear on it I will try it out when I get a couple cards out of the pj back. i think the marquee 8000 has the ability to move the image in the raster. It has been a while since I have been in the menu

Justin

Guys,

when you first do your image and raster centering on the crt furfaces, why don't you take off the lenses so you don't have to look thru them during this process??? Wouldn't it be easier with the lenses off???? Heck then you could put a mirror up in front on the pj so that you could move the centering magnets while at the same time seeing exactly what the results are.

Jim

I love this thread!

we have to keep it in mind forever!

any procedure for magnet raster centering on vph-12xx???

best regards

Bruno Lovisi

On my G70 the pj shuts off if the ground on the lens is not attached. MRW

Originally posted by Feathers
Guys,

when you first do your image and raster centering on the crt furfaces, why don't you take off the lenses so you don't have to look thru them during this process??? Wouldn't it be easier with the lenses off???? Heck then you could put a mirror up in front on the pj so that you could move the centering magnets while at the same time seeing exactly what the results are.

Jim

I would, if they weren't LC :( I just don't want to go there .. not yet anyway.

A few quick questions for Guy regarding your focus instructions using my NEC XG110LC:

(1) You mentioned to set the Scheimpflug by using a wrench. However, I believe the only way to adjust the H and V are by first loosening four screws around the lens and then it is possible to move the H and V settings. The problem is that your "3x5 card "technique requires active viewing which is not possible while the screws are left loosened. Is there a different way to move the H and V settings using a wrench or do I need to tighen the screws for viewing after each adjustment?

(2) I recently purchased this XG110LC projector and settings appear to be all over the place. Is there a way to do a master reset to erase all configurations and memories so that the unit is set to factory defaults?

(3) Will the master reset default all settings in option 9 - referenece settings? If not, is it useful to duplicate the levels of the settings in someone else's XG110LC as a safe default for reference levels?

Thanks for the "Holy Focus" manual. Do you have a "Holy Convergence" plan to offer?

Also, does anyone know of a qualified technician to setup proper greyscale and color balance on my NEX XG110LC in the Miami, FL area?

Craig

WOW. What a thread.

I'm bumping this because it recently came up and people have had a hard time searching for it. Did anyone ever HOW-TO or FAQ it?

I can't wait. I'm getting a BG800 and a BG808 next week and look forward to working this process. If I'm motivated enough, perhaps I'll document it.

Anxiously waiting for Guy's follow up to cover:


Speaking of which, the next steps in projector setup would be

Rough geometry and convergence
Grayscale calibration (with possible blue gun defocusing)
Final geometry and convergence


Specifically, grayscale calibration. I found that I got a much nicer picture from my current BG800 by defocusing the blue gun.

- Jerry

This ahs got to be the one of the most informative posts I have read here and there are a lot. I think everyone with a CRT should give this a read.

Can we P L E A S E make this a sticky thread on here or something? This thread is required reading for anyone with a CRT who wants to do setup themselves, or just know more about what goes into a setup process....

Well, ok, maybe all but page 5 is required reading, since much of page 5 is "bump". :D

The Holy Focus written by Guy is available on my web site in PDF format. It's well worth printing out.

http://www.monroe.net/~alyle/theater.htm

It does tickle me to see people using this and learning to do their setups better.

Guy Kuo,

You are the man!

Thanks for all that you have done.

Guy,

I agree with Pocatello,

You are the man!


Miso

Also see this thread http://www.avsforum.com/avs-vb/showthread.php?s=&threadid=288600

I have an NEC XG-1100 and in adjusting the CPC magnets I notice I get a LOT of raster movement. Since there are no raster centering magnets on this projector, once the astig is set by your procedure, it may take a lot of adjustment of the electronic raster centering controls to get the raster in the middle of the tube.

Is there a better way to do this, do I have to compromise astig setting so the raster stays where it belongs, or is it okay to do whatever is necessary to center the raster with the electronic controls?

Thanks!

Following the postings on AVS for the past year, at least once, since Guy started this thread, a person reported that the "blue" masking tape left a mark on their screen. Perhaps it was left on too long, perhaps it was not applied "lightly," or perhaps the glue on the tape reacted with their screen coating in some way. No matter what... I know that person was not happy with the result.

I posted my solution to this problem in another thread and it was suggested by several other members that I also add my solution to this thread.

Instead of blue masking tape... use two lengths of sewing thread.
Instead of using blue tape to mark the center of my screen, I stretched a black sewing thread across the horizontal and vertical center lines of my screen attaching the ends of the threads to the back of my screen frame (where any marks left by tape would be far less noticeable )

The two threads formed a cross-hair target that allowed us to easily set the center, skew, and bow when adjusting my projector's geometry. Since most of us have access to a spool of sewing thread, this method of locating the exact center of the screen is pretty easy to duplicate, just make sure the horizontal thread is stretched tight and does not introduce any additional bow.

Since my screen is suspended in front of my screen-wall, I have added four small screws, one in the center of each side, on the back of my frame. It is a simple matter now to stretch two threads, wrapping the ends around the added screws, whenever I want to check my alignment. (The added screws are partially driven into the frame, leaving part of the shank exposed to wrap the threads.)

Hope this saves someone from accidentally leaving a mark on their screen...

Joe L

http://www.keohi.com/keohihdtv/experttips/guykuo/guykuo_tips.html

I did not see this link posted before. It contains the Holy Focus technique with somewhat more pleasant readability and also further tips on astigmatism etc. Overall a great resource.

Guy: I have been searching for this information for a year. After reading this, I feel like I've just been in an intense lecture and have only grasped a few pearls. I will reread it until I have enough understanding to ask an intelligent question.

This is like food for the hungry. You are the MAN

Learned gentlemen:
I've got a Dwin HDP500 with Delta HD 145 tubes I have set up the projector and over 5 attempts it looks pretty darn good. All I did was mechanically aim the guns, do a center and edge focus, and then the geometry and convergence which I have gotten pretty good at. I'll bet that my centering of the raster is not good though, and I know the blue tube's cross screen focus is not as good as the red's. Who knows about my lens flapping capabilities of my beam astigmatism!!

Are there any hints with these tubes? Do the lenses come off? There appear to be two thumb screws on the back of each gun. Which is which? Any link to more detailed info on my specific situation.

Thanks in advance for any help you can provide.

Thanks Mr. Kuo for getting me thinking.

Scott

Speaking of which, the next steps in projector setup would be

Rough geometry and convergence
Grayscale calibration (with possible blue gun defocusing)
Final geometry and convergence

Those next steps are not discussed in this article.So, who's going to write up the details on those in as good a style, detail and intelligence as Mr. Kuo?

I have a SONY CRT VPHG70Q.. The shape of the Blue image on the screen is concave at the top (u shaped) and convexed at the bottom edge (upside down U).. The Green and Red are fine.
I have gone in the service mode using the remote. and tried to adjust the top & bottom edge shapes so that they are parallel to the horizontal center line of the screen using the vertical BOW key .. The status numbers change but does not seem to have any effect on the blue image? Any idea as what might be wrong/defective? Thanks.

Guy,

Thanks muchly for reposting this as I am trying to talk myself into reseting up my 1272 as I've just upgraded from SD cable to Digital, even with the crappy job I did on setting it up going to digital has improved the PQ no end.

I'm unsure what I'm going to suff up in going thru your setup proc.

Whats the worst thing that can happen ????


TIA

Bump!

This thread has been way at the bottom for almost five months.......Time to get back to the top!

John

It says that it was updated. What were they?

Nothing substantive. Just cleaned up and got the attributions at the start up to date.

Thanks guy for the post and the time you put into it...

some screen pictures of this process while doing it would have made thing seasier to understadn i think...
just a suggestion

thanks
Martin

hi fellows...

ok now i have been asking myself more wustions than before,,,
i just bought a barco 8xx projector for a fellow avs member near my house...
i brought it home and switched the celing/table top switches..
i have connected it to a svideo source and the pciture seems focused and nice but when i look at the screen (as oppose to the tubes..) i see three colors one picture...
i mhave read guy's post and got more of an understadning of what i need to do...
but here is what ia m wondering...

since this thing was set up prtty nicely at this guys house, by simply moving it i dont this that the g2 and other settings that are not meant for th edn user have not changed...hense i just need to center the tubes and do a convergence...
now am i right to assume that this pj just need a convergence and a aligfment oif the focus...or do i need to do everything described in that post...stuff like astig and other terms...

also since thsi is a barco and is not em focused..there is one manual forcus correct??

tahnsk for any info/help in advance..

Martin

If the beam setup was good at his place, it's worth checking, but likely will still be ok. You will mainly need to do the gun aim for your throw distance, and optical focus, and convergence. It is always a good idea to check the full setup though, and tweak if necessary. If you've not done this before, I would always tend to recommend that if beam setup is decent, to leave that to the future, and get a good solid picture with basic focus, gun aim, and convergence. Then delve deeper into the beam setup and such and get that spot on as you gain understanding about the set, etc.

thanks chriswiggles..

As i said it seemed to be in order when i saw it runinng..i also feel the same..i just want to get it converged and focused properly and when i feel more at ease try the beam settings and hwat not...
I have read guys post and understood most of it..with the exception of some of the more intricate settings..like blue being defocused or something to get good grayscale...i would think that this one would need a light meter of some type.,..
but otherwise understood the main steps and what to look for to achive a good picture quality..

He also talked aboiut of a point where the flying debrit looking stuff diapear when you get to that certain treshhold while looking into the binoculers,,but again i m noit sure if he meant looking to the screen through them or into the tube..i m sure its the screen but tehn i am alittle confused..so i figure you guys/gals shoudl know...

Thanks
MArtin

I'll have to admit it's been a while since I've read through his entire Guide, but I don't recall him talking about "flying debris" unless you break something.... ;)

If you could point me to that, maybe I could clarify what he means?

Second, about blue beam defocus, you will come to understand this better as you actually attempt to focus the blue beam. This is something I just typed on a different forum, that may shed some light on blue defocusing/focus:

"First, please don't confuse beam focus and optical focus, as these are two completely different systems, that add together to form the final image at the screen. A "focus problem" can be the result of either system being out of focus. This is related solely to blue BEAM focus, not optical focus!

Blue is difficult also for your eyes to focus on, so even if blue is quite sharp, it's difficult for your eyes to see it quite as sharp as the other tubes. This can make judging the focus of blue quite difficult, because it can be very difficult to get anything but a ballpark guess when doing beam focus and setup adjustments just looking at "sharpness." It is also almost impossible to see scanlines in the blue, even if they are there. A great strategy is to adjust focus, and in the range where focus seems good, there is usually a point where blue gets really well focused, and will dim ever so slightly. Move the focus setting in either direction and you probably won't observe any changes to line thickness, etc, but you may see blue brighten up a tad. Where it is dimmest, is your tightest focus. If you are trying to achieve more light output, then you can defocus the blue slightly to achieve that slightly boosted output. "

So you can help this attribute to help you focus the blue beam tightly, and also to get slightly higher top-end blue output capabilities if you need/want it.

Hope that helps!

that sounded more in debt that what he mentioned...
Regarding the flying debri..i was talking about the is called the gibbs effect..i believe...you get that "junk/artifacts" in the bckground of the picture in the colors that are more abundant...like black and while...specially white..
this was the reason that i went out and bought a barco crt and a video processor..over my infocus...and it is exactly this effect and other color mishaps that i wanna correct the most..
I have 20/20 vision with good attention to details,,,hense the smallest problem...that is present in almost most configuartions drive me nutts and stop me from enjoying the pciture...but i ahav ecome to reduce that effect on my x1 by fiddeling with all of the settings for a really long time...(almost from day one...six months ago!!!)

Also . am i correct to assume that i will probably not have to mess with the bean focus for right now...at least not untill i get better at this whole crt pj thing??

Anyhow thanks again

Martin

Could someone help me understand this paragraph? At first it sounds like he's saying the left most part of the phosphur is the best part, then he says it's the part with the most problems, then he summarizes by saying alot of techs will intentially use this part of the phosphur.

If someone could explain that, I would appreciate it. ALSO, it has been my understanding that the raster is best *centered* on the phosphur face to prevent convergence drift. So... I don't get it. :D

Originally posted by Guy Kuo
When viewed on screen, the leftmost portion of the raster is drawn first after the electron beam completes horizontal retrace. Looking into the projection lens the orientation is backwards. During the first portion of the horizontal movement the beam has not settled completely and one may see some waviness in the image if the extreme left edge of the raster is used. Some installers will intentionally displace the raster slightly leftward so the active image is displayed on the later, more stable portion of the raster.


Thanks! :)

He means that after the retrace there is still some ringing on the deflection voltage and so you get small distortions in the picture. This is the reason why there are the backporches after the sync signal. So the first few pixels after the retrace are not used.
Roland

that sounded simple enough to understand...at least for me!!!
the other "paragraph" had way too much info and scientific sounding wording for my tast...although i woudl think that with a little reasearch i woudl have gotten it,....
but when robro explained it my light bulb had a bright light so to speak!!!hehe
anyhow!!

Martin

No, I'm confused about his left and right. He doesn't clarify left or right on the screen is what the installers use. He makes it sound like it's the left side of the screen and not the left side of the phosphur face.

The left side is ringing as the yoke voltage and so the current ramp has to stabilize from the retrace pulse.
The right side is distorted because when the HOT is switched of, it still conducts some time (storage time of the horizontal output transistor) but due to the increased conduction resistance in the storage mode of the HOT the ramp is distortet.
That are the reasons of the back- and front-porches.

Roland
P.S.:
I am talking about left/right on the screen

CZ Eddie commented:
> it has been my understanding that the raster is best *centered* on the phosphur face to prevent convergence drift. <

That is generally true, although there are exceptions, which is what Guy refers to. I think the part that might be confusing you from Guy's explanation is this...

> Some installers will intentionally displace the raster slightly leftward so the active image is displayed on the later, more stable portion of the raster. <

Think of it this way... if the raster is centered, and the image within the raster certainly is, then that active image area will be relatively close to the leading (left-hand) edge. By shifting the raster off from center, to the left a bit, when you then re-center the active image area, it will be to the right of (outside of) that initial region where there may be beam settling deviations.

- Tim

Tim! That's it... that's what was confusing me!!!!!

DOH!

Yes, okay then... it makes perfect sense now. lol
What my eyes weren't passing onto my brain, was the "active image" vs raster issue.
I was reading them both as raster but in fact, centering a raster on the phosphur is NOT the same as centering the "active image" on the phosphur. Those are two totally different things and I don't know why I didn't think of that when reading the paragraph. sigh.

Thank you. :embarrased:

RoBro & Prehjan, thanks for trying to help. :)

so you are talking about a whole range??? (left to right...)

i hope that didnt sound too stupid!!!

anyhow
thansk folks

Martin

Originally posted by Prehjan
so you are talking about a whole range??? (left to right...)

i hope that didnt sound too stupid!!!

anyhow
thansk folks

Martin

Martin, RoBro's explanation helps explain why the raster is "messed up".

Now here is me explaining (hopefully the right way) what I was confused about. I'll need two posts to explain it.

Basically, the standard practice is to center a raster on the phosphur face and then center the picture within the raster.

Like in this attached pic:

But what Guy Kuo is suggesting is that some installers will not center the raster on the phosphur face. Instead, they shift the raster slightly to the left to avoid letting the active picture area into the unstable portion of the raster.

And then the picture itself is not centered in the raster, but rather it's shifted slightly to the right (within the raster).

So the active picture area is still centered overall within the phosphur.

The attached pic [below] is oriented as if you were standing in front of the projector, looking into the lens. Hopefully, someone will correct me if the orientation is the other way around, but I think I've got it right now. Um, "correct" now. :D

Looks OK, but you would go over the edges of the phosphor so the active area is maximized.
But then you have to take care if you use HTPC as at some resolutions the active image is larger inside the raster and may go over the edges. It is sometimes possible to use blanking to prevent this.
Most problems with this occur if you send a resolution to the PJ that is not setup yet for...
Roland

Yes, you have the concept now. Though, to be precise...

> The attached pic [below] is oriented as if you were standing in front of the projector, looking into the lens. <

the image you'd see in that case would be upside down (unless you were doing rear-projection). But it's easier to visualize the way you've drawn it. Nicely done. As usual, a pictorial example makes it a lot easier to comprehend.

- Tim

Thanks CZ Eddie for the explanation!!

yeah i also understood that what needed to be doen was the traditinal method..i mean that is how my barco 801s is set up...
but this alternative way...i will have to try and see for myself i guess!!!

anyhwo thank you folks for the info

Martin

bumpski

Did anybody write any maybe sort of definitive how to get it right CRT with HTPC,without going the {over taxing your bandwidth] situation

Instead of blue masking tape... use two lengths of sewing thread.
Instead of using blue tape to mark the center of my screen, I stretched a black sewing thread across the horizontal and vertical center lines of my screen attaching the ends of the threads to the back of my screen frame (where any marks left by tape would be far less noticeable )
.....

Hope this saves someone from accidentally leaving a mark on their screen...

Joe L

How about using a laser marker instead. These days you can get a toy laser for pennies.

K

snip
but again i m noit sure if he meant looking to the screen through them or into the tube..i m sure its the screen but tehn i am alittle confused..so i figure you guys/gals shoudl know...
snip

UH OH !
HEY ! DO NOT look into the tube with a binoculars ! You will permanently damage your eyes!

YIKES!!! :eek:


You are supposed to look at the screen with the bino's

After spending 8 hrs yesterday experimenting with all the information and advice given to all of us from the experts here on the forum, was able to get my ECP looking the best I've ever seen it. In fact, that after following Mike Newmans instructions for setting up an ECP, I can do a hard reset and have an image that's almost watchable (about 75% converged). So when I was done last night I thought, Thats it, thats all she's got. Wrong. I decided to try Guy Kuo's focus technique. Very time consuming, frustrating and worth every minute of it. About 1 1/2 hrs a piece for this partly because the tubes need to be cleaned off first or you may confuse dust on the face for phosphor grain. What this technique does is takes the guess work out and leave you with a stunning 3-D picture that you can't help but notice. The first 15 seconds of Cats and Dogs where the camera pans down through the trees made me feel as though I was floating down there myself. :cool:

Thank's to All

Chip S.




where is "Mike Newmans instructions"?

Yeeowza, I forgot all about this thread. I started this thread four on-the-roof projectors ago :D

Chip

Feelin your age, Chip? :D :p :D

Sorry I am very new at this. I have read for 3 days before I found this one from you Guy. Could this proceedure also be used on an RCA 52" projector TV? I can't find anything on it. model munber is p52921 manufactured in 11-1999 and was suppose to have a program within the remote to adjust the tubes but when I contacted them about it they said that was one of them that they had forgotten to program right and there was no way to adjust it without spending alot of money with a serviceman. We are seeing rainbow colors and hubby is about to chunk it out the door. I was trying to get it fixed for his Christmas but it can't afford for someone else to do it. Please help if you can. not sure how to see if you answered but I will try. :( thanks

Try to find out where you can get a SERVICE MANUAL.

This is an older model and it is a REAR projection TV (RPTV). This forum is for FRONT projection CRTs.

I looked around a little and could find no reference to this model #.

See if you have some contact information in youe owners manual that might lead you to the service manual.

excuse me for my ignorance for not nowing the difference. thanks for the help

Sorry I am very new at this. I have read for 3 days before I found this one from you Guy. Could this proceedure also be used on an RCA 52" projector TV? I can't find anything on it. model munber is p52921 manufactured in 11-1999 and was suppose to have a program within the remote to adjust the tubes but when I contacted them about it they said that was one of them that they had forgotten to program right and there was no way to adjust it without spending alot of money with a serviceman. We are seeing rainbow colors and hubby is about to chunk it out the door. I was trying to get it fixed for his Christmas but it can't afford for someone else to do it. Please help if you can. not sure how to see if you answered but I will try. :( thanks

This procedure will not work on this TV. Honestly, RCA's are not very high quality RP TV's and this is probably not worth fixing. Sorry for the BAD news. It also sounds like you have more problems than just focus.

Clay

Very nice post Guy. As usual, your knowledge, abilities, and willingness to share are exceptional.

craigr

true, great post but your comments have been delayed by 5 years!?? as this thread was made in 2001!:Djk.

If you don't top these great informational threads every few months, they eventually fall into the wasteland that is AKA "The Archive". Like the Marquee Maintenence thread did. :(

That's why I bumped it...

craigr

I learned so much from Guy

sadly he is no longer with us, and I don't mean passed away :D

-Gary

I learned so much from Guy

sadly he is no longer with us, and I don't mean passed away :D

-Gary

Yeah.
Doesn't Guy prefer an NEC HT1000 to an NEC 1352LC?
Huh?

...sadly he is no longer with us, and I don't mean passed away
I was going to say... I just had dinner with him not six months ago and he seemed fine then. You scared me Gary :eek:

craigr

he went DLP yes :(

-Gary

Every once in a while I give this a kick in the butt so it doesn't get lost :D

Chip

Is the 1080p already the stardard, coming with most new HDTVs, or is 1080i still the most prevalent? Thanks

UH OH !
HEY ! DO NOT look into the tube with a binoculars ! You will permanently damage your eyes!

YIKES!!! :eek:


You are supposed to look at the screen with the bino's

Reading back some of my post when i first started CRTing is funny to me!!!

Dam I was a green CRTer

...but since then graduated to a marquee and have gotten better at converging and focusing...(still learning though!!!)


Martin

A friend of mine looked at the sun through binoculars once - for about a nanosecond, and was blinded for about 3 days...

I've added Guy's excellent procedure to Curt's web site, along with some pictures to make some of it easier to understand and follow:

http://www.curtpalme.com/Focus_and_Mechanical_Aim1.shtm

More pictures to come!

I've used this procedure on all 3 of my CRT projectors and it's extremely logical and optimizes the performance of the PJ as compared to what's usually outlined in the manuals...

Kal

am I the only one that prefers the Blue tight up as possible for that extra bit of detail (blue tracking turned off on XG) ? :)
we can now compensate with point controlled gamma/greyscale from scalers ;)

-Gary

am I the only one that prefers the Blue tight up as possible for that extra bit of detail (blue tracking turned off on XG) ? :)
we can now compensate with point controlled gamma/greyscale from scalers ;)
You're the only one. :)

I doubt you can compensate perfectly at the source/scaler control as defocussing blue increases the blue light output at the top end to get better tracking. Compensating at the source or scaler could be done I guess, but at the expense of overall light output.

My blue's almost totally (electronically) defocused. EM blue focus is set to 0 on a scale of 0-100. It's not noticeable even on PC desktop fine text.

Kal

that would be correct Kal for my situation, I don't need the light output in my small room so with that scaler I can correct and can get the best of both worlds :) there is a light difference as you stated and those with big rooms or screens that crave light output will be shorted alot

I have compared many times trying to live with the blue defocused but it adds just a small extra flavor of sharpness and detail to the image and I just can't let myself defocus it :), the blue CRT in my 1352 is really really super sharp also, I guess I could just smidge it a little if needed

-Gary

I must have mine defocused too much. I can see fringes of blue around white text on a black background.

Revisiting the post :D .

I'll make this a sticky to keep it at the top...

I'll make this a sticky to keep it at the top...

Great idea, thanks!

Yikes, how many projectors ago was that for me :D

Chip

awsome thats cool!

Now i need to adjust the width coil and then the oriz. width of the three colours of my Marquee 9500 LC ULTRA.
Which is, in your opinion, the exact order of the other adjustments (ring astig., ring flare, raster centering, geometry, .....??

Thanks

well its very nice.

can u guide a little more, how to.......

i need to go to win update site then ???

I've added Guy's excellent procedure to Curt's web site, along with some pictures to make some of it easier to understand and follow:

http://www.curtpalme.com/Focus_and_Mechanical_Aim1.shtm

More pictures to come!

I've used this procedure on all 3 of my CRT projectors and it's extremely logical and optimizes the performance of the PJ as compared to what's usually outlined in the manuals...

Kal

It's good that there's a backup of this thread should AVS ever go by the way-side, god forbid.

I don't think many people realize that everthing that Guy talks about is equally applicable to RPTV's. I did all this w/my Toshiba TW56X81 many moons ago w/startling results that I can still see today. And I have little if any convergence drift at all.

great post, thanks for sticking it

Nice Post! Love it.

A good pair of binoculars, LMAO. Imagine looking at a TV like that.

They can help if you are looking at a relatively small dot from across the room.