Two Way Hourglass Bends on My KCS47 - Page 2 - Videokarma.org TV - Video

Chris K · #16 10-15-2025, 07:13 PM

I got it. The yoke in the maple TV from my restored TV giving me "the bends" is fine. The wing nut that holds it to the focus frame not only provides rotating the yoke when it's loosened but, the trapped nut on the yoke the wing "screw" threads into allows the yoke to travel forwards and backwards as well. The only way you can do this (because the yoke itself is in a housing and you can't get hands on it to push it closer to the CRT) is to loosen the nut and take a screwdriver and push the yoke forward and screw the wing nut tight while it's pushed. Then you need to check the yoke position on the bottom to be sure top and bottom are pushed forward equally. I think it's a bad design. If you need to rotate the yoke for an adjustment, you can't tell if the yoke has slipped back away from the CRT. You can't see it to check. Anyway, the picture fills the screen now with no bends. I'm eventually going to remove the entire housing and yoke to be sure everything is in the correct position. I only figured this out by working on the other yoke assembly that was originally in the strong CRT maple TV. On the bench it was easier to identify the potential problem. Thank you again Videokarmers!!!

Kevin Kuehn · #17 10-15-2025, 11:38 PM

Congratulations.
Is this the same bracket you're dealing with? Here it's missing the focus coil on the rear as it's jigged up on a KCS 40 chassis with the 5AP4 test crt, which needs no focus. This chassis is for a TC166 console which also has the 16GP4 crt.

Chris K · #18 10-16-2025, 09:30 AM

Yes that's it. Can you see it's the captured nut on the yoke that allows it to be m0ved forwards and back but you can't make that adjustment by holding the wing screw. Only side to side.

Chris K · #19 10-16-2025, 10:02 AM

Quote:

Originally Posted by Kevin Kuehn

Congratulations.
Is this the same bracket you're dealing with? Here it's missing the focus coil on the rear as it's jigged up on a KCS 40 chassis with the 5AP4 test crt, which needs no focus. This chassis is for a TC166 console which also has the 16GP4 crt.

Now that I can see how you have rigged this and I'm more familiar with the yoke/focus assembly, I might be able to pull the chassis and work on it for real on the bench. I have a 5AXP4. I see your ground clipped to the bracket. How did you get HV from the output socket on the HV cage to the test CRT? Is there anything more to removing the focus coil than removing the screws on the top (seen in your picture) and bottom? If I can work on it out of the cabinet, we can move on to the next issue...channel and sound not matching up. Been through this before and I hope there's an answer other than doing a full alignment!!!

I have an additional topic I'll post separately. The horizontal deflection circuit on these early TVs confuse the hell out of me. The KCS 47 has a horizontal hold, horizontal frequency, horizontal waveform, horizontal drive, horizontal lock, horizontal linearity and width adjustments. Just kill me now!

Kevin Kuehn · #20 10-16-2025, 11:34 AM

Yes the two rear screws with big brass washers remove the focus coil. Those washers are oversized so there's movement to center the fucus coil around the neck. The HV lead from the cage I have alligator clipped to another short HV lead with a normal anode button connector. Notice the large heat shrink that should be slid over that scary alligator interconnection while turned on.

I'm not sure if you realize those two elongated outer slots outside the yoke cage are the intended way to move the entire yoke assembly fore and aft along the CRT neck. I'm referring to the two slots I have the cage screwed onto my wood block supporting the test crt and yoke assembly. I'm using a spare yoke bracket and leave the sets hardware in the cabinet, so the 16GP4 stays mounted in the cabinet.

Kevin Kuehn · #21 10-16-2025, 11:42 AM

By the way the ground lead clipped to the bracket is just for piece of mind there's no voltage from the yoke leaking to it.

Chris K · #22 10-16-2025, 11:44 AM

Thanks Kevin...those 2 slots along the housing for mounting move the housing closer but if the yoke body is slid back within the housing, I still needed to slide the yoke forward. I can see in the anode setup photo, your yoke is in the forward position within the housing. My situation was the housing was pushed along the slots as far forward as the rubber cushions would allow but the yoke wasn't as far forward in the housing as it should have been.

Kevin Kuehn · #23 10-16-2025, 11:52 AM

Quote:

Originally Posted by Chris K

Thanks Kevin...those 2 slots along the housing for mounting move the housing closer but if the yoke body is slid back within the housing, I still needed to slide the yoke forward. I can see in the anode setup photo, your yoke is in the forward position within the housing. My situation was the housing was pushed along the slots as far forward as the rubber cushions would allow but the yoke wasn't as far forward in the housing as it should have been.

Makes sense. Just remember when mounting yokes you can't really get them too close to the CRT, so everything should be maximized in that direction. Also allows for more clearance of the focus coil movement, as you don't what that bumping into the rear of the yoke.

Chris K · #24 10-16-2025, 11:58 AM

Is there any issue with the yoke making contact with the CRT?

Kevin Kuehn · #25 10-16-2025, 12:09 PM

Quote:

Originally Posted by Chris K

Is there any issue with the yoke making contact with the CRT?

Sure, if there's a grounded dag coating and the yokes winding insulation fails. But that's the reason for those rubber bumpers. But as you probably noticed the housing limits it from exiting too far out the front.

Chris K · #26 10-16-2025, 02:15 PM

Point taken!

Chris K · #27 10-16-2025, 02:22 PM

I wonder if there's anything proactive that one can do to prevent winding insulation failures in yokes, power transformers etc. If you took a transformer core and submerged it in a varnish or shellac filled container for a period of time, could the insulation be beefed up to extend the life of the component? All these things will fail one of these days.

old_tv_nut · #28 10-16-2025, 03:45 PM

Quote:

Originally Posted by Chris K

I wonder if there's anything proactive that one can do to prevent winding insulation failures in yokes, power transformers etc. If you took a transformer core and submerged it in a varnish or shellac filled container for a period of time, could the insulation be beefed up to extend the life of the component? All these things will fail one of these days.

Don't know the answer in terms of a detailed procedure, but I do recall cases where the item being potted is put in a vacuum chamber to expell any air bubbles caught in the item - dunking may not be sufficient.

Kevin Kuehn · #29 10-16-2025, 06:03 PM

Quote:

Originally Posted by old_tv_nut

Don't know the answer in terms of a detailed procedure, but I do recall cases where the item being potted is put in a vacuum chamber to expell any air bubbles caught in the item - dunking not be sufficient.

Over on the ARF there's a couple Australian engineers that swear on cooking transformer windings in mineral spirits to dissolve any wax. And while it's still hot dunk in marine grade polyurethane varnish. The theory goes the hot mineral spirits draw the vanish inside and replace the solvent as it evaporates. There's a write up of the process.

jhalphen · #30 10-17-2025, 04:58 AM

Hi to all,
Hi @Kevin Kuehn,

the ARF thread on saving/restoring flyback transformers is here :
illustrated by many photos.

https://antiqueradios.com/forums/viewtopic.php?t=444436

See also the flyback restoration section (pages 2 to 4) in a Bush TV22 UK TV restoration article by ACORNVALVE of Australia.
38 page pdf, color photos :

https://worldphaco.com/uploads/BUSH_TV22.pdf

Best Regards
jhalphen
Paris/France