Convergence problem?

leopardus2

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Hi, I have installed a NOS Hantarex MTC9000 on my Exidy Mousetrap and am experiencing what seems a convergence problem. The problem seem to affect blue and red and not green, and is most visible on top corners. Please see attached picture.

Since I am no monitor expert, can you please tell me whether this is, in fact, a convergence problem, and whether it can be fixed? As I said, tube and chassis are NOS and have been tested before sending to me. The seller says maybe it went out of calibration in shipping.

Thanks in advance for your help!

Rick
 

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First, try reducing the image size on the screen, and see if that helps.

Does it have convergence strips taped to the back of the tube? The next quickest, easiest fix, which only really helps in the corners, is adjusting the convergence strips, or if it has none, adding some.
 
The convergence is off in the lateral parts of the screen in a symmetrical way. This suggests that the shadow mask has been dislodged from the left and right retainers as a result of a violent drop. In this case nothing can be done to fix that. You need to replace the tube. Just find a 20" Mivar and take its tube. It will work fine.
 
First, try reducing the image size on the screen, and see if that helps.

Does it have convergence strips taped to the back of the tube? The next quickest, easiest fix, which only really helps in the corners, is adjusting the convergence strips, or if it has none, adding some.

Not sure what a convergence strip is... will take a picture of back of tube and post it here...
will also take better picture of screen

Rick
 
The convergence is off in the lateral parts of the screen in a symmetrical way. This suggests that the shadow mask has been dislodged from the left and right retainers as a result of a violent drop. In this case nothing can be done to fix that. You need to replace the tube. Just find a 20" Mivar and take its tube. It will work fine.

Hmmm this doesn't sound good.. guess the mask is inside the tube?
Will check again this evening and post more pictures.

Thanks for your help

Rick
 
The convergence is off in the lateral parts of the screen in a symmetrical way. This suggests that the shadow mask has been dislodged from the left and right retainers as a result of a violent drop. In this case nothing can be done to fix that. You need to replace the tube. Just find a 20" Mivar and take its tube. It will work fine.

I doubt it's that bad, you'd get the same thing if the yoke had moved a little bit one way or the other (maybe one of the wedges fell out during transit), or if one of the convergence strips had scooted out of position or fell off completely. Both of which are more likely than a shadow mask issue, and are also pretty easy to fix.

Convergence strips look like the attached pic. They are little strips with magnetized ends that are stuck to the back of the tube to pull one or more of the colors into alignment with the rest at certain points on the screen. Adjusting the convergence with the neck rings and yoke adjustment can only do so much, especially at the corners, so the convergence strips are the final step in the process to fine-tune the convergence where the other adjustments can't get it done. Most monitors have multiple strips placed at various spots on the tube. I think a couple of those would take care of your problem.
 

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Hi guys,
as promised I'm back with more pics, including back of monitor.

Any help is appreciated, as I can fix game boards but am damn afraid of monitors!!

Rick
 

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Your dynamic convergence is off. Dynamic convergence is the area around the perimeter of the image. Dynamic convergence is adjusted with the position and tilting of the yoke. Ideally, I try to adjust the yoke until the convergence is about 90% good. Then the other 10% (usually the corners) is corrected with the strips mentioned in previous posts. Your static convergence (at least from the pictures) looks okay so I wouldn't mess with that yet. (Static convergence is adjusted with the rings on the neck so don't touch those.)
 
I can only confirm what I previously said. Ignore the other posts, they have no clue.
 
The static convergence is fine. Adjust the yoke. There's no reason to replace the tube. But if you want to be lazy, that's up to you.
 
I can give it a try at adjusting the joke, but am afraid to make things worse.
Can someone please give me some advice about how to go with this (I guess
small) adjustment? I have been advised by the seller to avoid untighten the
joke screw... he suggested to remove these rubber black things (that seem
glued) and try and rotate it a bit in one direction or the other,
but I really am not sure and very afraid of making it worse.

Thanks
Rick
 
The monitor manual is your friend. Most manuals describe how to adjust the convergence.
 
I can give it a try at adjusting the joke, but am afraid to make things worse.
Can someone please give me some advice about how to go with this (I guess
small) adjustment? I have been advised by the seller to avoid untighten the
joke screw... he suggested to remove these rubber black things (that seem
glued) and try and rotate it a bit in one direction or the other,
but I really am not sure and very afraid of making it worse.

Thanks
Rick

Rotating the yoke is going to rotate the entire image, which won't solve your problem. And don't remove the black wedges! That's terrible advice. What you want to try is changing the angle that the yoke sits on the tube neck. This is taken from a 4600 manual, but all yokes work the same so it should give you an idea of what to try.

WG%20K4600_Manual-6_zpsymwiy4fu.jpg


On the top two drawings, you can see that when the the yoke is angled upwards or downwards, it changes where red and blue cross over each other and the green at the edges of the screen. Angling the yoke left or right changes how they line up in parallel. It looks from your pics that you have a bit of both going on, but I'd try adjusting the up/down axis first before messing with the left/right one. The movements you are going for are very small.

The wedges are used to scoot the yoke angle a bit one way or the other, and when the convergence looks good they are glued in place and the yoke is tightened down. But if yours are already glued in, leave them there. They were glued in that spot to hold the yoke at the proper angle, and if you remove them you will have to start the entire process from scratch, which trust me you do not want to do. Adjusting convergence can be a frustrating process even for those who have done it dozens of times, and more often than not, you'll make it look worse than it did when you started... having the wedges in place means that if you screw it all up, you still have your "starting point" marked and can return it back to the way it was. So leave them there!

If the black wedges are still in place, what I would do is loosen the yoke screw enough that you can move the yoke, and gently move the yoke in towards the wedges to make sure it's up against all of them like it's supposed to be. Then turn it on and see how it looks. After that you can try angling it slightly one way or the other to see if that helps. You'll want the monitor out of the game, so you can watch the image as you move the yoke... convergence is pretty much impossible to do with the game in the cabinet unless you're a true expert.

You can safely touch the yoke itself with the monitor on, it does not carry high voltage is insulated (edited for safety/clarity). But other parts of the monitor (including, as MKL notes, the uninsulated yoke connection) are dangerous, so be extremely careful of what you touch and manipulate. If you aren't comfortable with it, don't do it. The best thing that can happen if you touch the wrong thing is you crap your pants and your arm aches for a week... that's the best thing.
 
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Thanks, this really helps. I am in the situation depicted in upper right drawing.
Green is okay, but red and blue cross like that. So I would have to tilt the joke by
putting some extra wedge on bottom side.

Thanks again, I'll let you know how it goes if I decide to try it out.

Rick
 
Thanks, this really helps. I am in the situation depicted in upper right drawing.
Green is okay, but red and blue cross like that. So I would have to tilt the joke by
putting some extra wedge on bottom side.

Thanks again, I'll let you know how it goes if I decide to try it out.

Rick

No problem, hope it helps. You may not need to actually wedge it just yet, you can probably loosen the yoke screw a little bit and just angle the yoke up or down by hand. The yoke could have just moved back from the wedges enough that it slipped away from the original angle, and scooting it back into place, without putting new wedges in, might do the trick.

Since your monitor looks like the upper right drawing, you actually want to correct it towards what's shown in the upper left drawing, so I think you will actually want to angle the yoke a bit up, rather than down.
 
You can safely touch the yoke itself with the monitor on, it does not carry high voltage.

I didn't want to post again in this thread but when I read these things...

There are 800-to-1000V on the *uninsulated* pins here:

attachment.php
 

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There are 800-to-1000V on the *uninsulated* pins here:

attachment.php

Yep. I've been bit by those pins several times while handling the yoke and looking at the image. Hurts like a mo-fo and makes me curse repeatedly. Still...for some reason, it doesn't stop me from doing it again. I'm gluten for punishment I guess.
 
There are 800-to-1000V on the *uninsulated* pins here:

You're right, I missspoke and should have been more clear: the yoke itself isn't going to zap you as you adjust it, but if you touch the lugs where it connects to the chassis you'll get a shock. As with everything in a monitor, you have to know what you're dealing with before you start rooting around in there!
 
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