chassis q, how can you tell if you need to swap yokes?

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partypooper

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im about to try swapping a chassis from a kortek to a wells, but i was curious if theres any particular reason to swap yokes. for instance if the impedance is the same and the pins are the same, would it still be necessary to swap the yokes?

i just checked the model numbers on the tubes, go figure, they're the same exact one. so is it safe to say this wouldnt need a yoke swap?
 
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ttooddddyy

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If the yokes are the same leave them alone, if you change the yokes you will have to adjust rgb convergence and colour purity which may be tricky if your not familiar with those settings.
 
Dion

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Its all about the impedence of the yoke. The tube can be the same but the yoke usually matches the chassis. If the impedence is the same then you are in luck.
 
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awesome, i think im in luck then. again just to be safe, its red to blue and green to yellow right, does it matter which one is touching red/black on the multi?
 
norton9478

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The current can pass through either way (it will just mirror the axis).

What you don't want to do is mix up or cross the streams.

One winding will have a higher impedance than the other.

I'm not sure which is which, but my guess is that the horizontal winding would have a higher impedance than the vertical winding.
 
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ok i just tried it, everything looks wonderful. the only problem is the screen is stretched WAY too far horizontally, and I was surprised to see that on the K7000 chassis there doesnt seem to be a horizontal size adjustment pot anywhere, which means i have to fiddle with the width coil, which i dont have a plastic adjustment tool for. :oh_no:

im surprised that even with the two monitors having the same tubes that the width would be so completely different.
 
ttooddddyy

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For reference sake, usually the horizontal scan is blue/red (approx 2 ohms) and vertical scan yellow /green (approx 30 ohms) This is the norm but not always the case with all monitors so be careful. If conected incorrectly the result is smoke and tears :(
Not sure about the 7000 but there may be a factory eeprom setting for the width control, will check the schem and advise.
 
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thanks tody. to be specific, its a K7100 chassis. I think the 7400 might have a pot adjustment for width size, and i thought this did too, but i cant find it for the life of me. just "H.Hold" on the chassis
itself :(

ok i just adjusted the width coil a bunch, it was all the way out (the shaft is really long itself) so I turned it in using the plastic tool i found and the width only went in a little bit. its still stretched out. could this have something to do with the B+ voltage? ive never messed with that before but i heard if its too low/high the picture could be the opposite (too thin.) again this is all so strange considering the tubes are the exact same model number. i still dont get why they wouldnt be the same.
 
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norton9478

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That width coil sucks...

You really have to crank it. I never had the plastic tool, I used a mini Metal Screwdriver (with plastic handle). It was kind of stuck, until i really cranked it.

It could also be broken (Right ttooddddyy?)
 
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im just afraid i might be turning it too much. the shaft is probably the longest shaft ive ever seen on a width coil, and it was all the way at the top. now its about level with the top of the copper colored wiring. im not sure if i should turn it any further, can it go past that without breaking?

http://www.arcadecup.com/ident/k700025.jpg

edit just to confirm if the yoke wires are swapped (eg. green and yellow) its only result would be a flipped picture right? it wouldnt cause this problem would it? this was also completely recapped and flyback replaced

i also want to thank everyone who chimed in to help me. this is why i love this place :)

again not to sound like a broken record but im completely baffled at how two tubes of the same model number could post completely different width results. if i took this chassis and put it back in the tube it came from, its width is fine, but with the better tube, that which carries the same exact model number, is completely stretched out to what seems to be beyond repair. id love to know whats causing this.
 
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ttooddddyy

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If you reverse the scan coil connections red/blue yellow/green it will only result in an inverted image (upside down/back to front) with no other advers effect.

If you connect the horizontal scan to the verical scan coils it will result in smoke, tears and greif.
 
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even though everything matched up, im afraid, for some unknown reason, that i may have to do the yoke swap in order to fix this horizontal width problem. how hard is it to do? ive tried searching for some good guides online but came up empty handed. theres one online that shows a bunch of pictures but nothing really detailing whether or not i can just go in there and start pulling things off.
 
ttooddddyy

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partypooper said:
even though everything matched up, im afraid, for some unknown reason, that i may have to do the yoke swap in order to fix this horizontal width problem. how hard is it to do? ive tried searching for some good guides online but came up empty handed. theres one online that shows a bunch of pictures but nothing really detailing whether or not i can just go in there and start pulling things off.
Click to expand...

It is not that difficult, it helps if you mark the convergence/ purity magnetic adjustment rings prior to removal so that you have a starting point to begin with.
Use a texter or correction fluid.
The good thing with MVS is that you already have a cross hatch generator (with no cart inserted)
 
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well i replaced the yoke and it fixed the horizontal issue everything seems to be fine except for one thing

qxut78.png


in the bottom right corner about halfway up the screen theres a brownish green tint to the monitor that i dont think degaussing will fix because theres a slight distortion almost a foldover in the image that isnt in the top half. i didnt swap the little convergence tabs that stick to the tube, you know the ones that are usually white sticky pads, i dont know if that has anything to do with it but im guessing no. anyway i think i might not have pushed the base of the yoke as far up the tube as i could have. would this cause that problem?
 
ttooddddyy

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Please post a pic with the cross hatch, looks like you have horizontal linear distortion.
The yellow colour on the rhs (purity error) is a different issue.
 
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i think i figured out what it was. after adjusting the width coil trying to get it to work on the original yoke, after i swapped them it was stretched a bit more than it should have been. turning it back seems to have fixed the foldover issue. now all i have to do is tilt the yoke a bit more to level out the image and fix that purity error. putting the deflection yoke closer to the tube didnt fix it as I hoped it would have, but maybe a degauss coil will do the trick.

ill post the crosshatch when i work on it tomorrow.
 
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