Convergence Problems

[chipper]

HI: I have just replaced the CRT in my 59 RCA Boswell set, with a GE 21CYP22A. and have a problem with blue or yellow horizontal shading around figures or between sky and earth back grounds . the yellow usually shows-up in a b/w picture. I have hooked up my RCA WR-64B generator and have done all the preliminary adjustments.(degaussing/purity/gray scale) and have a great overall color picture except for this. When I put the generator on dot and pattern do the red/blue/green dots converge into 0ne white dot, if so how is that accomplished. also I need someone to walk me through the crosshatch pattern, my directions are not to clear on this adjustment. I would appreciate any help you could give me on convergence adjustments . thanks chip

[ohohyodafarted]

Been A while since I did a convergence but this is basically what you do.

Disable blue and green guns so only the red is operating. On some sets there is are leads with spade connectors that you can pull off to disable the blue and green guns.

Degause your set with a degausing coil

Now with just a red screen raster, adjust the purity rings so you have a nice red screen, uniformly on the whole crt.

now re-enable your blue and green guns.

Some sets have a setup switch to disable the verticle. This switch will give you a horizontal line on the screen. Set the switch to setup position and then adjust your red blue and green gun drive controls to achieve equal intensity of all 3 guns. Then return the setup switch to normal position.

Now hook your dot generator up and tune in the set to create nice sharp dots. On the dynamic convergence board set your controls to mid point as a place to start.

The first thing to do is the static convergence. Adjust the permanent magnets on the convergence yoke so that you have perfect convergence in the center of the screen. You should have nice white dots. The 3 colors should converge nicely in the center area of the screen. There is also a blue lateral magnet that moves the blue dot left and right. The 3 magnets on the convergence yoke will move the dots at an angle of 120 degrees from each other, toward and away from, an imaginary point in the center of the crt.

Now attempt to converge dots with the dynamic convergence panel for the areas on the top, bottom, left ,and right areas of the screen using the controls on the dynamic convergence panel.

There will be some interaction of the dynamic controls. By that I mean that if you are, for example, adjusting red at the top of the screen you should also watch red dots at the bottom and elsewhere on the screen so you dont correct real nice in one area while making another area look real bad. I always tried for a good comprimise between one area and another. Then after I had a pretty good convergence, I would start all over with the static convergence again and do the whole thing over again. Usually you can improve on the first attempt after you have the controls on the dynamic board adjusted to there approximate range from the first attempt.

AS for crosshatch... Basically dots are the intersection of the crosshatch lines. The crosshatch allows you to see how linear your picture is. For convergence I woul use dots because you can see the effect of the direction you are moving the image more easily.

Like I said it has been a long time since I did a convergence, so other members please feel free to step in and add some refinments to what I have laid out here. I am sure that others have some little tricks that I have long forgotten.

Good Luck!

[Steve K]

Chip:

Bob spelled out the convergence routine pretty well. The only thing that I would add is that after you degauss the set initially and adjust for red purity, losen the yolk and pull it back (toward the CRT socket) as far as it will go and adjust the purity rings so that the red spot is in the center of the screen. Then push the yoke back toward the screen just until the entire screen is red. Sometimes if the yoke is too far forward the edges will be off.

Steve

[Chad Hauris]

Also make sure the convergence coils and purity/blue lateral magnets are lined up at the right place and position on the CRT...I can remember having problems on sets with seperate convergence yoke housings when it was positioned too far forward or back.

[chipper]

Thanks for all the info , I have followed your instructions pretty well. I am still having problems getting the blue dots to converge with the red and green. and I can tell this because in a good color picture I have horiz shading and below lettering I can see a blue shadow or ghost of the letters. I also have a purity problem in the upper left part of the screen, no matter where I move the red tabs on the purity ring. thanks chip

[blue_lateral]

Originally Posted by chipper

Thanks for all the info , I have followed your instructions pretty well. I am still having problems getting the blue dots to converge with the red and green. and I can tell this because in a good color picture I have horiz shading and below lettering I can see a blue shadow or ghost of the letters. I also have a purity problem in the upper left part of the screen, no matter where I move the red tabs on the purity ring. thanks chip

Great advice so far. A few things I would reinforce though...

Always degauss the set. If you have to go back and degauss the set again. NEVER skip this.

Do it all with the set in the spot it is going to sit. If you have to pull it out from the wall (proably), make sure it is pointing the same way with regard to north-south that it will be sitting. The magnetic field of the earth hs an effect.

Do the purity first and get it right before going any further. Pull the yoke back and do the red ball routine Steve mentioned. Push it forward until the purity looks good. I think sets a set with a 21cyp22a will also have little magnets around the edge to help you get the edges perfect.

Now would be a good time to check the vertical linearity. You will want to set the overscan. The RCA generator you mentioned makes square crosshatch. Make perfect squares. Note that most roundies have no width adjustment. Thats why you want to check this while you are moving the yoke around. Set the yoke position for best purity, but be aware of the width. A roundie yoke should NEVER be all the way forward. It screws the putity up, and also there will be too much horizontal overscan. Checking at this point in the process will show you exactly why.

If purity gets messed up by the convergence adjustments, go ALL the way back and start over with degaussing and putity. Each time through the routine you will get closer.

Once you have purity, check the static convergence using a dot at the center of the screen. If you can't get this right, go no further until you find out why. Don't touch any purity adjustmments (rings, yoke position, etc). Keep the brightness and contrast kinda down. It's easier to see when the dots are fairly dark. Note that the red and green are done first, as their paths intersect. Once you have red and green right, the blue magnet moves the blue dot up and down, and the blue lateral moves the dot sideways. You should be able to land the blue dot right on top of the red and green.

If they wont line up, note the following things about convergence magnets. The white/clear plastic style magnets can be turned 180 degrees in their spring steel holders to get more range (the magnet end will still be pointed at the tube. The bar style can also be reversed. I think you just turn them upside down to get more range. If a bar style magnet gets turned 90 degrees in its holder, it will have much less effect as you move it in and out, and may fail to adjust.

Blue lateral magnets come in 3 styles. a cylindrical thing you turn, a bar magnet that moves in and out, and a little flat magnet strapped right to the tube neck. The flat type is rotated around the tube neck to adjust. If you look inside the tube neck, you will see the blue lateral pole piece sticking up off the blue gun. The magnet should be over it, but rotated to the right. It goes at two o'clock.

Dont try to adjust the covergence panel until you get the static convergence right.

It's normal to have to go through the routine more than once on a set thats way out of adjustment.

Good Luck,

John

[chipper]

OK: Ive run into a problem on the convergence board. L-38 Right Horiz. Red-Green 1 and L39 Horiz.Blue 1 are frozen. Ive tried contact cleaner and if I try to force it, It only chews up the pot. chip

[reeferman]

Man if I had a buck for every RCA roundie I came across with that problem! I always preferred using the cross-hatch, except the dots for (center) static. I just lost the overall scheme of things using just dots. To each his own.. Sounds like you are on the right track, but I think you are going to have to compromise the convergence to suit your taste. Good luck.

[blue_lateral]

These are coils, not pots, right? Whatever you don't force them, and NEVER use a metal tool to turn them. If they're that stuck, I dunno.... I might try *gently* heating them with a heat gun. I haven't actually tried that. YMMV.

John

[chipper]

Coils Right: Would any have a Convergence Board assy for a CTC9A Chassis, The RCA part number is 106318. thanks Chipper

[bgadow]

You can swap individual coils or pots. I suspect you could use most any convergence board as a donor, at least an older one. I had some of the pot type that were frozen and I swapped them with no problems. Also, if you have listings for parts numbers of the individual coils you could search for them. Might be easier to find than a whole board. Moyers might have them.

[chipper]

Thanks Bryan: I did send them an e-mail today. 105065 and 105066 are the RCA coils I need. chip

[oldtvman]

before you even touch any of the static or dynamic convergence adjustments, always make sure all of the basic alignments are done first. such as linearity, height, width and then set your purity and if everything looks good then you can move on to the convergence adjustments. Previous posters in this thread also eluded to making sure the blue lateral and convergence yoke are in their proper physical positions otherwise you can end up chasing you tail on what otherwise would be a normal alignment proceedure. By the way my avatar is a Boswell ctc 9 as well.