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Looking for Convergence Strips


buttersoft

Question

EDIT: So I should note that while i rag on the use of convergence strips at one point in this thread, they actually work really well. The key is to make sure you insert them deep enough under the yoke - they should be at least 12cm long - and then wiggle them around a bit to see the effect they have. You can make some yourself from any thin piece of something magnetically permeable (permalloy, mu-metal), magnetic, or magnetically susceptible (the last meaning ferrous, really), listed there in order of effectiveness, stuck onto the end of a thin, flexible plastic strip about 6mm wide. I hear a little chunk of snap-off box-cutter blade works fine. Remember though, that setting up your tube properly to begin with is a better idea - you only use the strips to correct dynamic (corner) convergence when the setup leaves a few imperfections.

 

I'm going to have to perform some convergence correction, and was wondering about those little permalloy strips you see stuck in around the yoke. Anyone know a place to pick those up, or what can be used as a substitute, given permalloy is really expensive and mu-metal's almost as bad? Can you get that stuff cheap from anywhere?

 

I've also heard some people use little strips of fridge magnet? Or is that a bad idea.

 

Any info or tips appreciated :)

Edited by buttersoft
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CRT is gone, dead and buried. You won't find anyone stocking anything to do with CRT anymore.

 

Any bits around are likely to be used.

 

These strips do VERY LITTLE. They were sometimes used by the factories for final tweaking but in practice I found they do almost nothing.

 

Mu metal is the opposite of these strips - it was used to shield from magnetism mostly in critical applications like Oscilloscope tubes.

 

I suspect you are not performing the convergence/purity adjustments correctly if you have purity or convergence issues.

 

Some tubes just could NEVER be adjusted perfectly - many these days have been spoilt by looking at the PERFECT alignment of LCDs and when you look at any CRT it is never perfect.

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I suspect you are not performing the convergence/purity adjustments correctly if you have purity or convergence issues.

Actually i Haven't adjusted anything... yet. But the problem isn't uniform, and it's not quite limited to the edges of the screen, so i suspect i'm going to need more than the strips.

 

Mu metal is the opposite of these strips - it was used to shield from magnetism mostly in critical applications like Oscilloscope tubes.

You're saying they're magnetically susceptible, or just that they're actually little magnets?

 

Thx, but I already found that one. The guy stopped selling them a while ago :)

 

 

Thx for the replies, all.

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Errr, yes. So is permalloy, and i've seen convergence strips labelled as being made from it. But you're saying they're normally magnets?

 

I suspect both would probably work?

 

These strips are mildly magnetic (and are NOT made from Mu metal) - Mu metal is NOT magnetic.

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Many moons ago, one of my jobs was adjusting convergence (mainly in the corners) for brand new Ceronix CRT’s tested in the USA, but when powered up in the Southern hemisphere, all of them were out of whack.

 

I remember some tubes required around ten strips, but after a couple of years in the field, the poor old techs were getting calls for bangs and smoke, as the 3M tape holding them failed and they were falling straight onto the chassis below :031: As soon as LCD’s became cheaper, they switched.

 

As others have said, these strips only make small adjustments.

 

If you’re still after some, send me a PM with your address and I post some removed from old tubes.

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Hi buttersoft

 

I'd be interested to hear how you went with your convergence adjustment. I'm currently looking for some convergence strips to try and correct an issue with one of my corners.

 

Cheers, Ben

 

These are unlikely to fix your problem.

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These are unlikely to fix your problem.

 

This. They did exactly jack shit. I was advised of this, but insisted on proceeding. I suspect they're for very fine factory level stuff? I'm not sure though, because i've seen vids of them being used, and watched the changes. Vid below, for example, at 3:00. I have a couple of PVM's that want dynamic adjustment, so will keep trying.

 

If you have a problem big enough to see, you'll want something stronger to deal with it. Officeworks were selling a packet of 4 powerful little fridge magnets for around $16, and i used two of those right on the rim of the face instead. Not rare earths but still pretty strong. The further back down toward the neck you put them, tape them, silicone them, the more effect they have. The only thing to be careful of is that you don't use something too powerful near the grille/mask inside the face, and distort or destroy it. Start small, and see what's acceptable.

 

And make sure to stay away from the high voltage!

 

(if i could find a way to shrink this to a url, I would. It just keeps embedding.)

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This. They did exactly jack shit.

 

Sorry they didn’t fix your issue.

 

- - - Updated - - -

 

Hi buttersoft

 

I'd be interested to hear how you went with your convergence adjustment. I'm currently looking for some convergence strips to try and correct an issue with one of my corners.

 

Cheers, Ben

 

Back in the 90’s, my main job was ‘rectifying’ (especially) corner convergence issues with monitors, were talking many hundreds per year!

 

The trick was how to position (depth) the strip, sometime multiples in same position, along with ring alignment and a good quality degauss wand.

 

‘If’ you just have convergence in one or two corners, I just received two 1990 tubes that have multiple strips I can post you to experiment with.

 

If you’re not comfortable poking these around in a live monitor, maybe forget this idea.

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Sorry they didn’t fix your issue

Wow, that wa s realy rude of me, sory. It was totaly awesome of you to send them out, and probably my lack of experience combined with coarse old tubes. When i get around to it im going to dissasemble one of my bigger pvm's and give them a proper go. I seriously just couldn'nt get them to do anything to the tube i tried them on - had to switch to those powerful little suckers.

 

Anyaay, i need to try shit out for myself sometimes and just keep playing, and i'm not done yet, so i really appreciate you sending them!

 

- - - Updated - - -

 

Sorry they didn’t fix your issue

Wow, that wa s realy rude of me, sory. It was totaly awesome of you to send them out, and probably my lack of experience combined with coarse old tubes. When i get around to it im going to dissasemble one of my bigger pvm's and give them a proper go. I seriously just couldn'nt get them to do anything to the tube i tried them on - had to switch to those powerful little suckers.

 

Anyaay, i need to try shit out for myself sometimes and just keep playing, and i'm not done yet, so i really appreciate you sending them!

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Wow, that wa s realy rude of me, sory. It was totaly awesome of you to send them out, and probably my lack of experience combined with coarse old tubes. When i get around to it im going to dissasemble one of my bigger pvm's and give them a proper go. I seriously just couldn'nt get them to do anything to the tube i tried them on - had to switch to those powerful little suckers.

 

Anyaay, i need to try shit out for myself sometimes and just keep playing, and i'm not done yet, so i really appreciate you sending them!

 

- - - Updated - - -

 

 

Wow, that wa s realy rude of me, sory. It was totaly awesome of you to send them out, and probably my lack of experience combined with coarse old tubes. When i get around to it im going to dissasemble one of my bigger pvm's and give them a proper go. I seriously just couldn'nt get them to do anything to the tube i tried them on - had to switch to those powerful little suckers.

 

Anyaay, i need to try shit out for myself sometimes and just keep playing, and i'm not done yet, so i really appreciate you sending them!

 

You took my post the wrong way. All good, sorry they didn't help your particular issue. :052:

 

@Rustler77 maybe post a picture of your corner issue?

 

I'm no monitor expert, but you can get results skewing the corners with strips, just depends on how bad it is!

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I have since changed my mind completely on these things. Just redid the setup on a tube from scratch, pulled the yoke away, did the purity and then the rings, and afterward a few dynamic (corner) issues remained. The little strips, inserted under the yoke the deeper the better and then jiggled around, which part i'd never before realised was needed to see what effect they can have in slightly different positions, cleaned things up quite nicely. The end result is not perfect, but it's a fair bit closer than i could have come without the strips.

 

So yeah, they work a treat. I was obviously not doing things right.

 

I'd happily pay someone to send me another dozen, with a big thank you to @pauly540 for the first lot :)

Edited by buttersoft
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Before you start this procedure, I presume you have some idea of what you are doing

 

You have tried moving the 3 rings that control each colours convergence and one that controls all the colours I image?. They are the four, usually white, black or grey rectangular pieces hanging off the outer neck assembly.

 

They are often held in place by glue which you need to remove so you can re-adjust them without breaking the tabs clean off the rings they control.

 

Put the machine into a cross hatch pattern and using a mirror and working from behind the tube looking into the refection of the mirror, start turning them one at a time bearing in mine now that you have broken the glue, they will all move so you must hold the ones you don't wish to move.

 

The object is to get the red, green and blue, one at a time, all to line up at various points on the cross hatch with more important being in the center of the tube. Each ring controls a colour and one is a master that controls all.

 

You will never get the whole tube perfect, that is exactly what the magnets are for.

 

Once you have the majority of the tube converging nicely, (try to get all the errors in one corner of the tube if any), now grab a magnet about the size of a 10 cent piece was the type I used setting up brand new Taito tubes.

 

I have seen them in all shapes though, it really doesn't mater as long as they aren't to over powering.

 

Now move the magnet on the side of the tube you have issues with and watch the results. You will find the closer to the neck, the more influence. The more you move away from the affected area you are trying to fix, the more you will pull the correct part of the tube over however you won't upset that part of the tube as all the three colours will come over together if you know what I mean.

 

You may need to re-adjust the colour rings when you see what the magnet is doing a couple of times before locating the correct position to mount the magnet or magnets.

 

Some tubes are an arse and require multiple magnets but never more than three.

 

Position the magnet using BluTac as a temporary holder of the magnet.

 

Once you have a good "compromise" for the whole tube and after several goes have come to the conclusion this is the best you will get, remove the magnet, put silicon on the attaching side and using a small patch of tape to locate it till the silicon drys. No one ever removed the tape.;)

 

Glue the tabs back in place and the tube is done, ready for the next brand new Defender cab, oww sorry, just reminiscing.:blink:

 

Be very aware of the HT lead as it, while the tube is powered up, will continue to bite you, not just once like a powered down tube would.

 

Good luck, be patient and very careful. When I was first taught this procedure, it was taking close to an hour for me to get the tubes right. After about 50 tubes it was down to a 5 minute job per tube.

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