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Discussion Starter · #1 ·
I am setting up an 8500 and having problem with the very center grid as to converging the red and green. Every other grid is converged. The red vertical will not move far enough to the right to properly converge with the green. is this a problem with centering the raster or an other adjustment? thanks for any advice. steven
 

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After your rasters are centered, you should be doing mechanical convergence...if the center for your grid does not move far enough to the right, then it sounds to me like you didn't do mech convergence correctly.

You need to move that center convergence adjustment back to it's null point, loosen the red gun's mechanical convergence screws and swing the gun to line the center up. If done correctly you should have to use very little electronic adjustment to align the center of the rasters (center lines of your grid)

That's the whole trick to CRT, using as little electronic adjustment as possible.
 

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Guys!


If the yokes are positioned and aligned correctly on the tube necks then such problems can be minimized; perhaps the unit had been retubed without full attention to details; one also has to confirm that rasters are centered with all convergence nulled, and a few other things:


The yokes belong as follows: Scan yoke in front of course, be sure any original hot melt glue is removed from inside it; it must go as far forward as possible. Align the scan yoke for a level horizon with zone convergence nulled.* The second yoke is convergence and yours might be glued to the scan yoke; the convergence yoke is aligned so zone adjustments go straight up/down, no skew. Since the scan yoke has no clamp you want to hot-glue it to the convergence yoke, which does have a clamp. The third larger yoke is focus and stig, if you loosen the brass fasteners it can be wobbled about the tube neck and acts like a centering magnet and affects flare considerably; it has a clamp in back and a second clamp inside a small access hole; when correctly aligned you would have a centered raster on the tube face with static convergence nulled, and correct flare adjustment also. The rear-most yoke is flare; it is aligned by looking at defocussed dots and set so the hot-spot is centered in

the middle of the fog. To align flare correctly, select 31khz from internal frequencies (UTIL 1, 6, 2) the # for dots only, then Color 1, Color 2, Color 3 for one color at a time. Put PIC, 4 focus to 0, and contrast to 80-90, then rotate the flare magnet knob about the tube neck and also turn the knob in its' place for best alignment. When finished you should have a centered raster with static convergence nulled, for all three colors. Now confirm that all three crosshatch grids are centered on the screen; if not, then mechanical toe-in may need adjustment for red and blue; if green is not centered on the screen then the entire

projector needs to be aimed. Stig adjust is done in the Service Menu, UTIL, 9, 0901, 7, with 31khz as above but focus shoved to 100, 80+ on contrast. Set all dots for round. 31khz is preferred for bigger more visible dots. Also remember to match raster heights in the service menu, this is selection 3. Widths are matched with a plastic slug coil tool used to turn the width coils atop the horizontal sweep board, located in between the green and blue CRTs. The two front-most coils are for red, the front one is for below 60khz (low band sweep), the second coil is high-band or above 60khz) The middle pair is for green, same layout for

bands, rearmost coils are for blue. Finish up with zone focus (Service, 2) and geometry correction as needed, convergence and gray scale setup.


* To null static convergence only, push CONV, 1, 1; push CONV 1, 2 to null zones only; push CONV, 1, 0 to null both. That is for red and blue; for green push CONV, 5, 0901, and then push 2 and then 1, 2, or 0 as above. If you are working in a locked memory then you will recover your original settings next time you select that memory. I hope to have this and other useful information available soon on the E-Tech website which is undergoing total redesign.
 

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Discussion Starter · #4 ·
Whoaa, Tim, thank you for the comprehensive reply. I have to wait for the sugar high to recede (too many chocolate bunnies) before I tackle your steps. Ken, a thanks to you as well. I have tried to mechanically converge as far as the red tube will allow. I may not have the raster centering correct, though. The help guide instructs looking into the lense, but all I see is several rows and columns bordering a black square. Instead, i look to the screen and try to center by adjusting on the screen. Am I wrongly adjusting the raster centering?
 

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Sir


Center each raster on the tube face, then do mechanical toe-in. Sometimes in production the bottom of the tube cover got some hot glue on it and glued it to the foam below, making it hard to pivot. Fans under the tubes provide forced air to the horizontal board, focus board, and into the bottom of all three tube covers to cool the tube faces, yokes and neck boards. Do remember to avoid touching any exposed windings or solder points on the front-most yoke; the red/white/blue wires carry excess of 1000 volts and can bite some, as can a big arc from the tube glass itself.
 

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Discussion Starter · #6 ·
Tim, I am not clear as to the steps required to center the raster on the tube face. Do you mean take off the lense and then follow with other steps? I would appreciate a step -by- step detail of centering the raster. Thank you for your time and effort. steven
 

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cineprorocks,

Check out Guy Kuo's Holy Focus thread. It describes the method for raster centering (as well as mechanical focus).
 

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Cinepro, the ease way to see your rasters is to feed the pj a signal (DVD whatever) then turn the "contrast" way down to 5, look into the tube and start increasing "brightness", you may need to max it out. You will see a frame the same color as the tube light up around the image...that is your raster. If, when you light up the rasters they are somewhat centered on the tube face, when you don't have anything to worry about. I have been told by Tim that you may not be able to perfectly center the rasters, however they should be close.

If one or more is not well placed in the center, then centering requires rotating the Focus coil, and adjusting the Flare magnets...as I think Tim mentions above.

As you rotate the focus coil, you will see that the raster moves in a circular motion, this will then effect flare, and you will go back and forth...until you get a feel for how one effects the other, then you may be able to set one half way, and adjust the other and all will be right. I didn't figure that relationship out until a started the third (and last) tube.
 

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Guys!


On a Marquee the positioning of the focus yoke is a large-scale centering alignment, the flare rings affect centering to a lesser degree. The focus yoke is loosened at the brass fittings at its' rear (not the clamps) and the yoke is wobbled about the tube neck until centering is achieved. This affects flare as well, so one has to set centering and check flare and go back and forth a few times between the two adjustments. It can take up to an hour to center and flare one tube, it is a bit tricky even for those ofus who do this every week.
 
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