Please stop "OHMING YOKES", replacing k7000 flybacks along with some others.

arcadecup

Well-known member
Joined
Oct 3, 2006
Messages
2,848
Reaction score
232
Please stop "OHMING YOKES", replacing k7000 flybacks along with some others.

For the love of preserving this hobby STOP OHHMING YOKES please everyone.
If you are going to port in a tube at least port the original yokes over.
Ohming out a short is not and will never be the proper way for matching yoke reactance.
You will either overdrive your flyback, underdrive or be within spec and everything is fine (maybe, in a pseudo sense). Anything over driven or demanding higher than spec current will likely cause earlier failure. Drawing too much current with in the yoke and flyback will generate more x-rays and possibly go into an avalanche mode where it's more than TV limit regulations setting off geiger counters. Even porting over to a different tube with the original yoke does not guarantee a proper run due to gun bias differences and in really picky ones tube capacitance changing high voltage potential.

I get about 4-7 emails a month about ohming yokes. Please live with your burn and original tube. Please stop replacing k7000 flybacks that work as the replacements are far inferior. There are some flybacks where a replacement is surprisingly better than oem ; unfortunately not many. If its oem and working, please leave it. Sometimes more damage is done than intended good.

As far as lytics there are many boards that it makes sense to cap out without a doubt. pulling -testing them, putting back in would actually be more time consuming rather than pulling 20 and replacing them in most cases. You might have 3 confirmed bad caps, you might have 1 you could have 1 totally dead cap and maybe the rest all have drift an are on the way out. Would i recommend a full cap out on modern stuff like the d9200 or kortek 2914? absolutely not.

The real problem though is yoke mismatching with all this. It is an absolute epidemic. You can probably get away with the higher tolerance boards like the k7000, g07 era stuff. Easiest way to explain ohming a yoke is akin to measuring the weight of two different cars by eyeballing alone rather than the proper way with a precision scale. Hope this helps to bring insight and concern for the sake of keeping our beloved monitors healthy and original as possible.
 
Last edited by a moderator:
I've replaced 15 or so tubes in K7000 with matching yokes and never had a single problem.

I think I need more than just "don't do it, it might be bad". :D
 
So just swap the yoke and tube without reading the resistance? Even better!

Just kidding of course. I realize it is inductance you actually need to match up ,not resistance, unfortunately inductance is impossible to measure for the average dude.

Always best to keep the original monitor yoke. We have touched on this in a podcast or two.
 
While I can understand Chad's sentiment on the matter, the rule of thumb I use is this:

  • If the yoke is bonded on the TV tube you want to use, PASS.
  • Always use the OEM yoke with the main chassis.
  • While YMMV with different tube/gun setups, at least you know you won't be over/under driving the fly. The only issues you'll have with a tube that doesn't match up well with your OEM yoke is image display problems rather than electrical issues in the HV/yoke circuit.

I've never used a multimeter on a tube in my life. Don't intend to. If I'm swapping a new tube into a monitor setup, I just make sure it's a proper angle tube, with anti-implosion strap ears mounted in the correct orientation, and correct neck socket. Match those and you've got a fairly good chance the tube will display a favorable image.
 
you can probably get away with most TV yokes with K7000s by virtue of their relation to Zenith. I don't know how that compares to non-Zenith makes, but whatever. I've never used a TV yoke for a swap before.
 
Not to derail this thread, but please explain more about this... :confused:

Yes please...

Technically, it's called an "implosion band." It's there to keep the tube from exploding outward in a million pieces when the tube is broken. The band exerts inward pressure on the tube, instead causing the tube to "implode" on itself when it's broken. Anyhow, lesson over. Why do the ears matter?

Manufacturers had two choices when attaching the "ears" to the corners of the CRT tube before the implosion strap was affixed. Depending on whether or not the CRT ears are mounted on the tube-face side of the strap or the bell side of the strap, it will cause fit issues with the monitor frame you're dealing with.

Nearly every arcade monitor I've ever come across uses a tube with the implosion strap ears mounted on the "BELL SIDE" of the tube, not the tube-face side. If you try and fit a tube with the ears mounted forward (incorrect) you will shift the tube face (and consequently, the neck and whole tube) backwards about 1.5 inches, causing the monitor to not line up correctly with the surround, bezel, and even worse, you risk the neck and/or neckboard not having enough clearance to allow the back door of the game to shut properly.

The only way to ensure that the replacement tube will correctly fit the OEM monitor frame and game fitment is to make sure you have selected a tube with mounting ears in the same position as the original tube - which is "ears back."

I've seen folks have some minor success with using longer bolts and spacers to bring the tube forward back into the correct position, but that only works if your game allows for a free-standing monitor installation. If the tube is directly connected to any wood framing or bezel opening that's part of the cabinet construction, this option might not work. My double dragon is a great example of this.

Always look for the following in a 19" tube swap:

  • correct neck socket
  • correct deflection angle (90 or 100)
  • Ears back
  • Yoke NOT bonded
  • NON-Trinitron, must be a regular ol' curved CRT tube (no flat tubes)

As long as you meet those criteria, you have a pretty good shot at a decent tube swap.
 
Cool, thanks!

200_s.gif
 
Meh you burn a chassis you burn a chassis. K7000's aren't that rare and there's plenty of scumbag sellers here on klov selling chassis at insane prices. I've taken a 13" tube with it's yoke that came with the tv and hooked it to a 19" chassis no problem. Ima need more than resistance is not a good measuring technique.
 
Even porting over to a different tube with the original yoke does not guarantee a proper rune due to gun bias differences and in really picky ones tube capacitance changing high voltage potential.

Please explain how to guarantee a proper rune.
 
Never been a fan of modding a chassis to make it work. These were engineered for specific reasons and that is how they should be.

Now for tube swaps I don't do them. Hate doing convergence and purity adjustments if you have to swap the yoke. (I suck at doing them). Yes I have a 19" TV tube I use as a test fixture. However I wouldn't use it in a game.

Example if you have a chassis that has a width problem with the the original board and it didn't have the problem before, repair the problem. Not patch it by replacing the width cap with a different value to change the width. That's not repairing that is jerry rigging and can only cause more problem later.

For the love of preserving this hobby STOP OHHMING YOKES please everyone.
If you are going to port in a tube at least port the original yokes over.
Ohming out a short is not and will never be the proper way for matching yoke reactance.
You will either overdrive your flyback, underdrive or be within spec and everything is fine (maybe, in a pseudo sense). Anything over driven or demanding higher than spec current will likely cause earlier failure. Drawing too much current with in the yoke and flyback will generate more x-rays and possibly go into an avalanche mode where it's more than TV limit regulations setting off geiger counters. Even porting over to a different tube with the original yoke does not guarantee a proper run due to gun bias differences and in really picky ones tube capacitance changing high voltage potential.

I get about 4-7 emails a month about ohming yokes. Please live with your burn and original tube. Please stop replacing k7000 flybacks that work as the replacements are far inferior. There are some flybacks where a replacement is surprisingly better than oem ; unfortunately not many. If its oem and working, please leave it. Sometimes more damage is done than intended good.

As far as lytics there are many boards that it makes sense to cap out without a doubt. pulling -testing them, putting back in would actually be more time consuming rather than pulling 20 and replacing them in most cases. You might have 3 confirmed bad caps, you might have 1 you could have 1 totally dead cap and maybe the rest all have drift an are on the way out. Would i recommend a full cap out on modern stuff like the d9200 or kortek 2914? absolutely not.

The real problem though is yoke mismatching with all this. It is an absolute epidemic. You can probably get away with the higher tolerance boards like the k7000, g07 era stuff. Easiest way to explain ohming a yoke is akin to measuring the weight of two different cars by eyeballing alone rather than the proper way with a precision scale. Hope this helps to bring insight and concern for the sake of keeping our beloved monitors healthy and original as possible.
 
Never been a fan of modding a chassis to make it work. These were engineered for specific reasons and that is how they should be.

Now for tube swaps I don't do them. Hate doing convergence and purity adjustments if you have to swap the yoke. (I suck at doing them). Yes I have a 19" TV tube I use as a test fixture. However I wouldn't use it in a game.

Example if you have a chassis that has a width problem with the the original board and it didn't have the problem before, repair the problem. Not patch it by replacing the width cap with a different value to change the width. That's not repairing that is jerry rigging and can only cause more problem later.

I can appreciate your sentiments, Ed, but the fact of the matter is this: there are a select few technicians in the world that romanticize the pure science behind CRT technology and work in that thought process, and then there's the rest of us, who are tinkerers. Tube swaps have been happening for decades, this is not new news.

I'm not sure your argument regarding changing a capacitor value in the deflection circuit is in the same vein as Chad's comments. I would equate the capacitor change to adjusting a potentiometer - not a risk to the circuit. Running a flyback transformer through a yoke that's not correctly matched is a whole different level of discussion.

Us arcade guys have been modding things since the beginning of time. My stance is as long as it works for you and it's not emitting dangerous radiation, have at it. Tinker at your own risk.
 
Last edited:
Wait - so did I read this correctly. Is Chad saying tube swapping a K7000 without swapping yokes is putting me at risk for additional X-ray exposure?

Even if they OHM close?
 
Us arcade guys have been modding things since the beginning of time. My stance is as long as it works for you and it's not emitting dangerous radiation, have at it. Tinker at your own risk.

How do you know if it's emitting dangerous radiation? I'm not aware of cheap home testers for this...
 
Back
Top Bottom