Tube swap yoke question

don1400

Member
Joined
Apr 9, 2005
Messages
459
Reaction score
11
Location
Green Bay, Wisconsin
Hello,
I'm doing a tube swap on a Wells 4600 and before I took the rings & yoke off the donor tube I checked the yoke for compatibility and found the resistance readings to be very close to the Wells, was wondering if they were close enough to use the yoke.
I found the below info for the Wells on the forums, I measured the donor yoke.

4600 yoke donor yoke
Blu&red 2.7 ohms 3.1 ohms
yello/green 8.3 ohms 9.4 ohms

Anyone know if the specs on the donor are close enough to give it a try?
Thanks for any help.
Rich
 
Hey there,

Ill wait for another more experienced member to reply... but i think they have to be with in half an ohm to an ohm of eachother.
 
Resistance does NOT = impedance.

Just because the yokes share similar ohm resistance doesn't mean they'll work in a swap.

Use it as a guide, but not gospel.
 
You can try it and will probably get a picture. BUT - you might have some issues like focus that ALMOST dials in, or a slight warping of the image in the corners (not perfectly square).

But, since the 4600 has wires from the chassis that attach to the yoke, and the donor yoke probably has wires from the yoke that attach to the chassis, you'll have to splice the wires (which negates switching to the 4600 yoke later). Might be easier to just swap the yoke.

Mark the rings positioning on the donor tube before removing them, so that you can put them back in the same spot. If the donor tube has rings and yoke as all one piece, then swap the rings on from the 4600 tube. Measure their positioning and alignment on the original tube before removal, and try to position them the exact same way on the donor tube...
 
You can try it and will probably get a picture. BUT - you might have some issues like focus that ALMOST dials in, or a slight warping of the image in the corners (not perfectly square).

But, since the 4600 has wires from the chassis that attach to the yoke, and the donor yoke probably has wires from the yoke that attach to the chassis, you'll have to splice the wires (which negates switching to the 4600 yoke later). Might be easier to just swap the yoke.

Mark the rings positioning on the donor tube before removing them, so that you can put them back in the same spot. If the donor tube has rings and yoke as all one piece, then swap the rings on from the 4600 tube. Measure their positioning and alignment on the original tube before removal, and try to position them the exact same way on the donor tube...

You're right I will need to splice wires, however I have some tabs that connect into the 4600 yoke wires clips so all I need to do is solder them on to the wires of the donor yoke. What is the worst that could happen if the Wells chassis doesn't like the yoke? Can I fry anything on the chassis. I read on a post somewhere that the yoke could fry but won't hurt the chassis. Is that correct?
Thanks,
Rich
 
I did a tube (and yoke) swap on a 4600 with the following specs:

Original K4600: 9.0ohms & 3.2ohms
New Donor: 10.9ohms & 3.0ohms

As smalltownguy correctly points out: this ain't inductance. But it's the best thing we can easily measure, I suppose, to get us close.

As modesitt warns, there are no sure bets in tube swapping. My TV donor tube has nice bright colors and no burn in (of course), but I had to swap the width coil in the chassis to get the width overscan under control, and the geometry has a little bit of wonkiness I can't adjust out. Overall, it'll make a fine test bench monitor (which is what it's being used for now), but I don't think I'd put it in a game...
 
Thanks for the help guys, I'm gonna give it a shot this weekend and if I have good results I'll post model & tube number from the TV.
Rich
 
Thanks for the help guys, I'm gonna give it a shot this weekend and if I have good results I'll post model & tube number from the TV.
Rich

Well I wired everything up, plugged it in and got a pix that was too big, I adjusted the vertical & horizontal size, no problem with the vertical but the horizontal is either at the end of its range or it's stuck, couldn't move it any further. Didn't make any adjustments other than H&V size and focus, looks pretty good. Here's two quick pictures.

donor2.jpg


donor1.jpg


If I can get the horizontal corrected and once I do all the other adjustments/degaussing I think I have a winner.
Rich
 
Hey there,

Is there no width coil ? Or is that what you have been using to adjust ?

My guess, (and this is just a guess) is that you would have to replace some of the ceramic caps near the Hrz output transistor with different values to get the picture to contract a bit.

Ken or someone else should beable to confirm this.
 
Yes, if you've been using the horizontal width coil and you've exhausted the totality of the travel, then you'll need to modify the Polypropylene capacitors near the width coil.

Bob Roberts does a great job explaining how to do this:

http://arcadecontrols.com/BBBB/width.html

He also sells a monitor width kit so you can do your own modifications.
 
Yes, if you've been using the horizontal width coil and you've exhausted the totality of the travel, then you'll need to modify the Polypropylene capacitors near the width coil.

Bob Roberts does a great job explaining how to do this:

http://arcadecontrols.com/BBBB/width.html

He also sells a monitor width kit so you can do your own modifications.

Thanks for the info from Bob's site, I remember seeing that years ago and never would have thought of it. I did a quick white balance alignment, and checked the B+, picture much better and now you can see the word credit on bottom of screen fully, picture still needs to get a bit smaller horizontally, so when I have more time I'll try some caps as suggested on Bob's site. One thing I notice now that I have a much cleaner picture is that the convergence is off in a number of places, looks like the original seals are still on the rings and yoke so I don't think they were messed with, yoke and rings are on tight. Even though I'm using the original yoke and rings with the tube can the different chassis cause the mis-convergence? I'll probably take the monitor over to Chad's and have him do a complete alignment and see if tube needs to be rejuved.
Rich
 
Back
Top Bottom