Tube Swap: How long does it take

Physical swap - 5 minutes. Convergence - up to 30 minutes, but I am not too picky. I now have a signal generator that should make the convergence much easier/faster.
 
5 minutes. It's going to take me that long for me to get my tools ready. Take all the hw off and everything only took you 5 minutes?
 
Well, I have no idea where you want to start from. I started from the basis of a prepped replacement tube (stripped from the TV, convergence ring placement marked and rings removed, yoke removed, anode cup removed, etc.) sitting next to my chassis with all cables from the chassis to the current tube removed. The tube is held on by four screws, remove them and put the new tube in place. DAG should move with the tube but sometimes the DAG is mounted to the frame. Loosely install the yoke and convergence rings, connect all cables, connect to your video source and begin the convergence procedure.
 
My tube replacements have been with TV tubes to GO7 chassis. It usually takes me about 1/2 hour roughly. I usually try to make sure I use the original deguassing coil which requires drilling out the rivet in the dag shield.

Luke
 
Besides the convergence, how long did the above take?

My starting point is a G07 on my left and an encased TV on my right.
 
This is something I would like to see a video tutorial on how to go from start to finish. I fear the convergence at the end.

Theron
 
Swap is super easy so long as the donor tube has a compatible yoke and the yoke uses the same connector. Also note that some degaussing coils are not compatible with certain chassis. Keep the original if possible.


Swap tube: 10 minutes including discharge, unbolt, rebolt.
Swap deguass coil or convert coil connector if necessary: 5 mins
Swap yoke connector if necessary: 5 minutes

This is all it takes to 'create' a new monitor out of a donor TV and a Wei-Ya or Jen-Shin chassis provided you find the right yoke match on the donor tube.


Now if you need to swap the yoke, add a large amount of time to mark convergence rings, remove and mount a new yoke, get a pattern generator (specific device or boot screens from various boards) and start your aligning process. You may need to move, remove or add metal deflection bending tabs between the yoke and the tube as well.

Then onto convergence. You might get lucky or you might end up being so far off with the new yoke you'll need to start from scratch. Good luck is all I can say. It isn't fun without the right equipment. Some times no matter how long you spend you just cannot get the tube to reconverge due to a core difference in the shape of the tube as compared with the original. The tube + yoke + rings make the combination work. Pulling off the donor yoke and putting on the arcade chassis yoke may mean you just can never reach perfect convergence again.

In many cases it's just easier to buy a chassis known to work with a specific series of donor tubes with attached yokes and not deal with trying to swap a yoke and converge. I don't know about others, but a $40 used or $70 new specific chassis off ebay and a free tube = 20 minutes of swap time is a lot better than wasting hours trying to swap yokes and converge a tube.

I've only had 1 good K4600 + yoke swap, and one 'close convergence' K4900 + yoke swap. GO7 just has never worked for me. And in all 3 cases, donor TV tubes with compatible yokes have been hard to find, since most are 15 ohm vertical resistance while a K4600 is 8, and a K4900 is 48 and a G07 is 55 ohm. That's why it's easier to just buy the replacement chassis and pay myself to not waste hours trying to converge -- And then I end up with a brand-new looking sharp, and converged as well as the TV was image as a bonus. But then again I'm not a tv tech with great equipment.
 
Last edited:
Yeah, I'm hoping I don't have to swap the yoke as well. Maybe I'll make a video to show people.
 
This is something I would like to see a video tutorial on how to go from start to finish. I fear the convergence at the end.

Theron

NO! NO! NO!

Use the convergence rings on the TV [and their positional settings as found on the donor TV] for the final monitor. DO NOT walk through the convergence procedure.

USE the original yoke from the monitor; DO NOT hope that the 'new' one will be compatable.

Saltbreez
 
NO! NO! NO!

Use the convergence rings on the TV [and their positional settings as found on the donor TV] for the final monitor. DO NOT walk through the convergence procedure.

USE the original yoke from the monitor; DO NOT hope that the 'new' one will be compatable.

Saltbreez

You have to make sure the yoke on the TV has about the same impedance as the one that is normally used with the target chassis, otherwise you MUST swap the the yoke that goes with the chassis to the new donor TV tube.
 
Last edited:
Generally speaking, for best results, remember this: Convergence rings stay with the TUBE, the yoke stays with it's CHASSIS.

When possible, you might be able to get away with using the TV yoke on the arcade chassis, but it must be the correct impedence. But in most cases, you'll have the best picture and the least release of magic smoke if you keep the yoke with the chassis it was designed for, and move it onto the new tube.

-Ian
 
If the resistance of the windings on the yoke are close, you won't release magic smoke. At worst you'll have bad geometry like pincusion or corner tearing. It's the inductance differences that causes that. Vertical resistance levels of 8-16 will work on 8-16 chassis just fine. Vertical resistance levels of 45 to 55 work on 45-55 chassis just fine, but in all cases you may have geometry issues if the inductance is off.

K4600/K4900/G07/20EZ are the ones that are the hardest to find a matching TV yoke for. Others are much easier in my experience.

I have numerous WeiYa, Jen-Shin, MTC9xx and K7xxx series chassis connected to TV yokes with absolutely no geometry problems and never had to swap yokes. But then again these are not the more common chassis out there.
 
I swapped a tube on a K4900 the other day with no blue. Start to finish took about 7 minutes. No convergence adjustment necessary because I:

1) Marked the exact depth and placement of the centering rings before taking them off the new tube.

2) Made sure the wedges were placed properly for the yoke being transferred on.

3) Put the old rings back in the exact same place as before.

4) Installed chassis, hooked it all up, and had a perfect picture when it powered up....
 
Just a note, the last one I did had the purity rings and yoke all as one assembly and couldnt be seperated. Luckily the impendance matched a 4600 so thats what I used it for. If you dont have to move the yoke or rings its a straight forward easy deal.
 
Back
Top Bottom