Does anyone repair yokes? Is it even possible? (WTB - Red Tent XM-1801 yoke)

[Alpha-tron]

Heat is always an issue when dealing with induction circuits. It not the copper wire that normally fails but the insulation that fails. Constant heating and cooling cycles. Dissecting the circuit that drives the yoke is worth looking into. Adding some sort of cooling system should help in the long run.

 

[TheYeti]

Dumb question, but are you guys sure there isn't something about your chassis that are burning up yokes?

I like the soft drinks theory, but am wondering what else could potentially cause this. I do like drilling into systematic failures like this, so I'm interested to understand what the root cause is here.

Definitely not a dumb question and I've considered this myself. At this point, I can't definitively say if my chassis is or isn't burning up yokes. Anything is possible at this point. LOL

Do you think this would happen if too much "juice" is being applied to the yoke from the chassis? Do you know how I would be able to safely validate this?

Here is a picture of all my extra yokes right now. The 3 on the left are original red tent yokes. The one on the far right is supposedly a k7000 yoke but it doesn't look exactly like the k7000 yoke I transplanted on a friend's red tent monitor a few months back. (I can expand on this later as it might be the most viable option)

Anyway, they are all burned up on the inside. Unfortunately, I don't have a picture of them before I used them, but I suspect they all looked like this before me.

 

[TheYeti]

And here is a picture of my friend's yoke up close. The corrosion was so bad when I got this yoke that the wire was literally severed inside. I pulled the wire out for the picture.

 

[andrewb]

What's the brown goop? Does it dissolve in water? Is it some kind of glue used in the manufacturing process? That's a bit curious.

Looks like something is corroding those yokes (or rather damaging the insulation on the magnet wire).

 

[TheYeti]

What's the brown goop? Does it dissolve in water? Is it some kind of glue used in the manufacturing process? That's a bit curious.

That's clear epoxy they applied at the factory. I fear that will be impossible to remove if I decide to disassemble one of these for repair. It's tough as nails.

 

[andrewb]

That's clear epoxy they applied at the factory. I fear that will be impossible to remove if I decide to disassemble one of these for repair. It's tough as nails.

Ok.

I can't really tell from the pics, but are those yokes more corroded/burned on the bottom halves? That might support your soda theory.

 

[TheYeti]

Ok.

I can't really tell from the pics, but are those yokes more corroded/burned on the bottom halves? That might support your soda theory.

Oops...I just realized you were referring to the brown stains on the inside of the yoke.

Yea...I'm not sure what that is??? I'm also not sure why all of these yokes seemed to have some kind of 1in tape applied inside the yoke as well. The strips are brittle and basically crumble away when I touch them. You can seen rectangular remnants of them in the 3 on the left. (Maybe those were small convergence strips installed at factory?)

 

[Alpha-tron]

The stuff that removes the expoy will also remove the insulation also

 

[Alpha-tron]

Would a yoke off of a 13" a34agt13x work?
Thin neck 8 pin g1 of 50v 6.3 heater voltage
It a small 13" TV
Whitter has nothing but 13" monitors a tvs

 

[TheYeti]

Would a yoke off of a 13" a34agt13x work?
Thin neck 8 pin g1 of 50v 6.3 heater voltage
It a small 13" TV
Whitter has nothing but 13" monitors a tvs

Crap...I don't know!

I'm sorry guys, this is where I'm going to reveal my inexperience. I understand how to take a ohm reading on a yoke...but I quickly don't understand how to measure impedance and I don't know what "heater voltage" means.

Do you know what the ohm readings are for that yoke?

 

[Alpha-tron]

Crap...I don't know!

I'm sorry guys, this is where I'm going to reveal my inexperience. I understand how to take a ohm reading on a yoke...but I quickly don't understand how to measure impedance and I don't know what "heater voltage" means.

Do you know what the ohm readings are for that yoke?

Heater voltage. Just voltage it takes make the gun side of the tube glow.

Different tubes sometime different heater voltage..

I am not sure if that coil will work or not. You might end up with an image that is 13" on a 18 inch screen..

I will get you the ohm readings.

But am at garden grove looking at the monitor room there.

Lots of vector stuff one 25" monitor and a pile of 19" stuff..

It would be cool if we could find a TV version that works. I think they make a lot more TV compared to 18" crt screens

 

[TheYeti]

Heater voltage. Just voltage it takes make the gun side of the tube glow.

Different tubes sometime different heater voltage..

I am not sure if that coil will work or not. You might end up with an image that is 13" on a 18 inch screen..

I will get you the ohm readings.

But am at garden grove looking at the monitor room there.

Lots of vector stuff one 25" monitor and a pile of 19" stuff..

It would be cool if we could find a TV version that works. I think they make a lot more TV compared to 18" crt screens

I plugged the red tent tube model number into Tubular and here are the specs:



So it looks like the specs match up? Just need to know the ohm readings.

 

[Alpha-tron]

Ran across two thin neck at banning..

Something like a k7000..
69x1586-100 is the only identity mark on a stick on the metal chassis
3.0 ohms 13.0 ohmshy ouhe other is a kortek k1-2-v0
Orion tube a48jll40x18
41.8 ohms 3.3 ohms
Let me find my meter for the ohm readings

 

[TheYeti]

Ran across two thin neck at banning..

Something like a k7000..
69x1586-100 is the only identity mark on a stick on the metal chassis
3.0 ohms 13.0 ohmshy ouhe other is a kortek k1-2-v0
Orion tube a48jll40x18
41.8 ohms 3.3 ohms
Let me find my meter for the ohm readings

Thank you so much for looking around for me Alpha-tron. Very generous of you to help me try and find a compatible yoke.

 

[Alpha-tron]

Thank you so much for looking around for me Alpha-tron. Very generous of you to help me try and find a compatible yoke.

Going to being a meter to check out the 13" crt over at Whittier today.

Cross your fingers..

At banning still need to check those 100v crts in the new tech room. Still need to check the broken crt in cargo containers.

Still need to check in the green house and las tunas.
I think there a thin tube lurking here or there.

Glad to help a fellow arcade collector..

 

[ArcadeJason]

Heater voltage. Just voltage it takes make the gun side of the tube glow.

Different tubes sometime different heater voltage..

I am not sure if that coil will work or not. You might end up with an image that is 13" on a 18 inch screen..

I will get you the ohm readings.

But am at garden grove looking at the monitor room there.

Lots of vector stuff one 25" monitor and a pile of 19" stuff..

It would be cool if we could find a TV version that works. I think they make a lot more TV compared to 18" crt screens

old post now did you find a yoke?
about the 13" pic on an 18" screen idea
the deflection angle is directly proportional to the screens size based on the distance of the yoke to the tubes screen. in other words since the 13" yoke is further away on a 18" tube the screen will be the exact same size (that is of course if the yoke has the same values)
for example a standard wg6100 yoke can be used in a 25" starwars cockpit

also somewhere a mention of heater voltage
the heater produces free electrons next to an exciter plate which attracts those electrons toward it because of a potential voltage difference (electrostatic)
. some of the excited electrons fly past the plate (due to a hole in the middle) and then move through the focus grid which depending on voltage shapes the beam. with no heater voltage you cannot have a beam (under normal operation of course)

 

[TheYeti]

old post now did you find a yoke?

Hi Jason!

Yes, I did. A fellow KLOVr ended up selling me his a yoke from a Sharp XM-2001N.

It's interesting that this yoke has pretty much the same ohm readings as a stock XM-1801N yoke...but the picture doesn't fill the screen entirely. There was a 1 inch border around the entire edge of the screen. Also, I had to back the yoke down on the neck to get the image to look correct.

Now I was able to adjust the picture for the most part and got it looking pretty good. No problem getting the picture to fill vertically using the vertical height pot.

However, I can't get the picture to fill the entire screen horizontally. I have the width coil maxed out.

But all-in-all, I'm still super thrilled I was able to track down both a tube AND a yoke. Something I'll probably never be able to do again.

Oh, and this new yoke is in great shape. Zero corrosion. Unlike all of my original red tent yokes. They all had corrosion. I'm convinced now that it comes from spilled drinks.

For reference, the top picture is a stock XM-1801N yoke. (Notice the picture fills the screen)

The bottom picture is a XM-2001N yoke on an XM-1801N tube. (notice the white edges on each side)