Yoke question

obitus1990

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Why do some deflection yokes have what I can only refer to as metal "ears" or "tabs" attached to the plastic shell that face towards the tube, while others are just the plastic shell? What is the purpose of the metal "ears?" What's the proper terminology for the "ears" and are yokes with and without them classified differently?
 
Why do some deflection yokes have what I can only refer to as metal "ears" or "tabs" attached to the plastic shell that face towards the tube, while others are just the plastic shell? What is the purpose of the metal "ears?" What's the proper terminology for the "ears" and are yokes with and without them classified differently?
it works. just play your games.
 
In all seriousness, I'm asking because I have a K4900 with an open winding on the yoke (not at the terminal where it could be resoldered, somewhere deep in there that can't be found). It's an older model that uses a different yoke from the late model with the extra vertical position pot. I have a spare chassis that has the extra pot, as well as the proper deflection yoke for it, so that's what is going on the tube when I replace the non working yoke. The old yoke doesn't have the metal tabs but the new one does. When converging and doing purity adjustments to the to be repaired monitor, are the metal tabs to be used to support the wedges or do they have some other purpose?
 
The metal bits you're asking about are not really used in the purity/convergence process that you plan to do. I don't know of any reason they are there. I suspect it was some sort of production process need. Or maybe something magical, but again it doesn't matter to the P/C work you're going to do.

The 4900 3/4/5 pot chassis use different yokes. I seem to recall maybe the 4/5 pots use the same yoke??. Anyway make sure you pair the yoke to the chassis.
 
Yes, I have the proper yoke for the 4/5 pot chassis.
You could carefully unwind it, noting the number of winds, and then re-wind it with new wire. It's tedious but do-able.
 
To paraphrase @mecha , I'd rather play my games.
I get it - I really do.

Maybe when you are successful, you can post it for someone who may need it, and who likes the challenge of a rewind. I've seen a few posts here about it - it's a very interesting and challenging job!
 
Why do some deflection yokes have what I can only refer to as metal "ears" or "tabs" attached to the plastic shell that face towards the tube, while others are just the plastic shell? What is the purpose of the metal "ears?" What's the proper terminology for the "ears" and are yokes with and without them classified differently?
They are used for pincushion compensation together with special windings of the vertical toroid coils. All is pretty much described in US Patent US4556857 https://patents.google.com/patent/US4556857A/en?oq=US4556857
 
They are used for pincushion compensation together with special windings of the vertical toroid coils. All is pretty much described in US Patent US4556857 https://patents.google.com/patent/US4556857A/en?oq=US4556857

The abstract (don't have time to absorb the whole patent) suggests that this patent deals with bonded yokes that don't have rings.

and achieves self-convergence and four-sided pincushion correction by means of the cathode ray tube and yoke only.

So maybe in the case the OP asks about, 19k4900, which does have rings and was available before 83 (?), this isn't the case for the metal ears? 1984 patent so I'd think RCA wouldn't have produced that and then filed after.

Still interesting none the less, thanks for that.
 
So maybe in the case the OP asks about, 19k4900, which does have rings and was available before 83 (?), this isn't the case for the metal ears? 1984 patent so I'd think RCA wouldn't have produced that and then filed after.
There are plenty of other patents that suggest the same thing as the mentioned patent. I do not see any connection between bonded yokes and using metal cross-arms with "ears". The earliest patent I have discovered is from 1981 but the idea of using metal cross-arm structures to correct for East-West pincushion is as early as 1961.
A good example is the Amplifone deflection yoke (not bonded) which is design to correct for East-West pincushion and is using cross-arm structure.
 
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