Last post about my convergence
 

I know there is not such thing as perfect convergence on CRTs, especially older sets, but I need to get closer than I am. I'm used to seeing a little red or blue on edges of images, but they've always been less than an 1/8". What I'm dealing will on the right and left edges are separations of up to a 1/2" and covers 2" on the left side and 6" of the right.

I know it should get better than this. No one would buy a set if the convergence were this bad. Since I've done all the electrolytic caps, could it be a resistor or capacitor on the convergence board?

I'm attaching a pic. Don't pay attention to the bottom lines. Those are lined up now. I had then lined up, but made them that way when tried to get the edges better. The sides are still as messed up, but not the bottom center horizontal lines.

http://www.youtube.com/watch?v=2wYn3xLrZj0

again you need a scope to make quick work of this. does the blue horz coil have any effect?

Nice video. I wish mine was that easy. I've replaced the blue coil and it has the same results as given by the original one before the core cracked.

Since things on the board are pretty interactive, could it be another pot or coil? I know there's one pot that doesn't really cause much movement on the screen. It could be an issue.

I did deoxit all of the pots and treat them with fader lube, but it only made them turn better.

other than checking all the parts its hard with out a scope. feel for cold resistors (esp large ones) same with pots (they get warm), lastly the diode pack may be bad.

This is what I try to avoid part replacement to fix a problem, sorry if it sound negative, it just a hard way to fix things.

Another reason I need to get my brother and his scope over here. This may seem like a lame question, but how do I know what to set the scope to? The SM doesn't have anything about working on the convergence board.

well there is a vert pulse and a Horz pulse so you just setup so you can see them. you bro should know for his scope where those are.

if the blue coil does nothing don't over look the convergence cluster itself, check the coils for continuity where they terminate at the convergence board

Think I'll pull the convergence connection so I can put the whole thing on the bench and go over it.

Davewm has you on the right track. All the waveforms are shown on the
conv socket if you got the sams. Convergence probs are
rare, tube zeniths had diode packs go & left blue pots.
your biggest hint is if any controls dont work or
barely work. And dont forget you often have to go back & forth
allot sometimes inc. the middle.
BTW the right is always the hardest.

73 Zeno:smoke:

the blue is always out slightly on these zeniths but that is way off.does the blue move at all when you adjust it?if not check solder joints.then go to resistors.doubt if it the diode pack is defective but anything can happen.

The blue coil moves the lines up on the right, but then totally messes up the left side. I can get the left pretty close, but then the blue horizontals at the top of screen are off. The only way to get the top horizontal lines converged is to back off the coil and let the right and left get that far out of whack.

There is one pot that doesn't seem to do much at all. There's barely a difference and I should have noted it and figured out what it was supposed to adjust. I don't remember which one it was and will have to go back and start turning them again.

I was able to check the resistors in circuit and they read at their values. Not sure how to test the diode pack. Don't think it's an easy removal and I doubt it can be tested in place.

I used the ohm setting to check each pot and coil and not were "open". Don't know what else I can check. Gotta get my brother's scope.

Well I'll be.... Didn't even notice the convergence is part of the schematics! I really need to pay better attention.

It seems the blue pots are moving things around, but whether they are doing it as designed, that's another story. I know there's one pot that isn't doing much when turned, but I forgot to note it and now have to find it again.

I don't know of any way to test the diode pack.

...

Well there are two (coil and pot) that work together to move the horizontal blue up and down from center towards the top and bottom of the screen. Then there's another pot that works with the coil just mentioned that adjusts the horizontal lines on the left and right sides of screen. Their interaction has to be going wrong somewhere as the red and green lines meet up on the sides.

The thing is, the compromise I've made is to allow the right and left to look like crap so I can get the center to look good since it's the main viewing area.

you have to constantly touch up the static as you adj the dynamic, and I hope you did the purity 1st or you are wasting your time as a purity adj will throw ALL convergence off.

purity
center static
then the order in the sam on dynamic
touch up center as you go.

I did manual degauss using a coil, purity, grayscale, static and then dynamic. Was told that static doesn't need adjusting after being set and only dynamic should be adjusted.

The center of the screen looks just fine, it's the sides that are way off.

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on this model there should be another coil for blue convergence.i believe it is a smaller one,that controls the blue centering.i am almost positive on this one.

Yes, there is a blue convergence magnet (with adjustment) and a blue lateral (with adjustment).

The center could use a little touch up, but until I can fix the sides, it's not of great importance.

I started wondering if it's really the blue that's the issue. What if the blue lines are where they're supposed to be and the red and green are off? They seem to interact with each other quite a bit, so if a pot is bad, maybe it's affecting them. Of course I have no way of knowing all this until I get the scope (which I hope to get today). If I get the scope I might be posting the model and some pics and asking for assistance in the settings. :scratch2:

small problems at the center get worse at the edges, you need to always check and touch up the center static as you make dynamic adjustments, it does not take much.

That being said the pic you posted shows more that the typical problem with blue.

I hate trying to do the center convergence. It says to use the dots for it, but the dots are so fuzzy and I expect a pure white dot. I know this isn't possible, but my brain is so picky most of the time it keeps me tweaking it. :screwy:

really important to turn brightness down (is this that same set?) setup the focus to get as small a dot as possible, setup in a dim light. Use a hand held mirror standing behind the set dont shock your self to get the center and adj the static. you hold the mirror up close to the screen center while standing behind and adj the magnets.

Its a PITA to do it this way but its the only as you need to get a real close look as you go.

sorry,i forgot it was flat chassis.vertical sets have a smaller coil that moves the blue horizontal centering.

Yeah, it's the same set. I think I should get the G2s set properly before I do the center convergence again. I have a full size mirror, but are you saying I should put one hand on the convergence knob, lean over the top of the set and look into a hand mirror that's up close to the screen? How about a magnifying mirror up close to screen and I stand behind the TV and adjust? Or will the magnifying mirror distort the dot?

Here is a pic showing the convergence board and it's plug. I don't know why they bothered with a plug since removing the board would also involve unsoldering the convergence magnet wires. Quick disconnect means nothing if it's only half of the wires involved.

...

Yep, I learned that from my brother. I said to him I thought it was an odd way to mount the controls and he said to flip it up so I can easily adjust while in front of the set. I was so busy wondering why it was mounted there I never thought about it being functional with a little movement.

I get it. You can take the chassis out and work on the bench. I've been flipping her over and it works for me. If I had a business going, I'd sure go the removal route.

If I jumper the terminals of a convergence pot while it's turned all the way down, there shouldn't be any movement of the lines, right? I would like to do a little testing of the pots on the board and figured I'd jumper the terminals of each pot and see how it responds. Then I'm going to run them through their full range (un-jumpered) and see what kind of range they have on the screen. I'll finish it off by giving the pots another deoxit and fader lube session. Once that's complete I'll try the convergence procedure over again, starting with the center convergence.

Can a pot be accurately measured while still connected? If I connect to the terminals and turn the pot, can I expect a close to accurate readout? If so, should I be looking for a full range (0 to stated ohm value), or do they not zero out fully CCW?

I figure if something is wrong with one of the pots, this should help me determine.

Okay, did another cleaning with deoxit on all the pots and followed up with Fader Lube to keep them lubricated. I then tested each pot and found one that makes a clicking sound at full CCW and you can also feel it. I checked the resistance across the tabs and it was much lower than the other two pots of the same resistance (120ohm). Two showed that value, but this one only showed about 23ohm. When I connected to the wiper, the other two pots showed 1.2 to 123. This one started at 1.8, when to 27.9 and then started to drop back down to 2.8 and never go anywhere near it's value of 120.

I tracked down an NOS pot and will be purchasing it long with the R/G vertical lines right coil. It is seized in the position left from last adjustment.

I'm attaching pics of the current convergence I've achieved. I think with the pot replaced and the new coil, I should be able to tweak it to make it better. I know perfect is not possible, but I'm pretty close to a convergence I can live with.

Thanks to many here, I'm almost there!

this is as good as your going to get.all my zeniths look about like this too.turned out very nice.you will never,ever achieve absolute perfect convergence.from about 5-10 feet away,it will look perfect.nice job and now sit back,relax and enjoy this masterpiece!

Still have to replace the one pot and coil. Both are responsible for the right lower section that is still quite a bit off. Watching a B&W image is painful as it's not just a little blue or red on an edge in the image. It's a large blue, magenta and yellow edge on almost everything in the lower right. It immediately pulls your eye to it and is quite distracting.

While I know perfect isn't possible, those lines should be closer together. I should have the replacements here and installed by next Monday (hopefully).

not that far off.you can tweak some more and maybe move purity rings very slightly to pull it a little closer.the blue horizontal could move a little more north.i know how this is.you want it perfect.tweak it some more just in those areas but it looks much better than it did and is close enough to enjoy.great progress.set looks good.now some screen shots,please?

This set only has the two purity rings and am not sure how they can help with convergence. It took me a manual degauss, movement of the rings and yoke to get purity done. Movement of those rings is sure to mess up my purity.

Like I said, I'll wait until the new coil and pot arrive. Until then I'm going to let the convergence be and enjoy what I have for the moment.

when you were checking those pots remember some of them may not test right in circuit. You would have to look at the schematic to see if they are isolated.

sometimes you have to comprimise the dynamic convergence, get one side perfect and the other is off a lot, in that case you shoot for the same defect on both sides. How much is normal and how much is a defect in a part can be hard to say. Just remember the idea behind dynamic convergence is to get the lines straight if thats done then it should be pretty close when the static is right on.

there was a post in the early color where a member (6GH8 cowboy IIRC) was having some convergence issues and it was bad caps. If I was have problems I would break out the scope and see if I could see the needed waveforms going to the coils. if they are there then it clear the parts as an issue so just focus on correct setup. Make sure you have all the neck parts in the correct position.

I followed your suggestion and touched up the static as I was doing the dynamic. It helped a little, but most of the improvement came from a second cleaning of the pots. Still, to get the better sides, I had to sacrifice the lower horizontal convergence and especially the lower right corner.

The one pot that tested oddly also had a click that sounded like a wire might have come unwound or something and was clicking as the wiper pushed it over. You could even feel it in your fingers. The coil is a given as it's seized. I'm pretty certain you can't lube the core of them. They seem pretty porous and I'm sure it would ruin the core.

smoothly working pots is a def plus. the zenith coils (if they are the plastic ones) can be a real PITA as the plastic crystalizes.

Yeah, I noticed the pots and coils run around 100 degrees and that has to take it's toll on the plastic coils.

Hope you folks don't mind, but I'm going to sticky this thread. I've almost given up on vintage color sets because I can't get convergence right, and this is a great reference for anyone working on this :)

Okay, I should have the 10x probe for the scope tomorrow. Here's a questions about testing the convergence board. I see in the Sams that each of the test points corresponds to a lead in the convergence socket. It would be much easier to test the leads if the socket were disconnected. That way I could touch the probe directly to each pin in the socket. That's where my question comes in. Is it okay to run the set with the convergence board disconnected. I know the convergence will be way off and there will be no power to the convergence magnets. Other than that, would I cause any damage to anything?

Thanks!

If it was a tube set I would think the worst thing would be a somewhat reduced vert scan, but since its a solid state set I would advise against it. Nothing worse that making matters worse while trying to make them better.

I suggest you figure a way to make contact solid, with the set off turn on note pattern then shut down for removal of test probs. Beside unless the sams says to disconnect then it would be assumed the reading were taken with the plug attached.