Curtis Mathes C20/ctc15/16 clone Focus magnet/blue lateral???
 

Hello,

It apears this magnet thing with a spring holding it around the neck that looks like a focus magnet has disappeared. I need to locate a new one. Not sure if it is a focus magnet or if its to adjust the blue vertically? Does anyone know? It had a long yellow wire solderes to it, maybe a ground wire.

Wrong on most counts...The blue lateral magnet moves the blue beam side to side to converge it. The blue moves in two axes X (adjustment on top convergence clover petal), and Y (blue lateral).

There were no round screen color CRTs with magnetic focus. Focus is electrostatc and takes 2-5KV from the flyback system.

Some blue lateral magnets were grounded to prevent capacitive charge buildup that could bite a tech adjusting it.

Some later lateral magnets were integrated with the purity ring assembly (I can only recall seeing it on rectangular CRTs though).

Good luck on your search.

So it was a blue lateral probably?

Your description is too vague to be certain. A picture would help.
The average round screen color has 4-5 things on it's neck: the "Deflection Yoke" that goes somewhere between the end of the electron gun and the bell of the CRT, the "Convergence Yoke" which looks like a BIG 3 leaf clover with the CRT neck sticking through center which is normally placed over the big metal ring at the end of the electron gun (sometimes hidden but denoted with a red stripe in the CRT neck), the "Purity Rings" which look just like magnetic centering rings found on monochrome TVs, the "Blue Lateral Magnet" which was made in a few different styles that all interchange and is typically found over IIRC the second large gun element from the base, And lastly the "CRT Socket" that the CRT base pluggs into.

Some sets had a combined Purity Rings/Blue Latteral assembly and thus had only 4 things on the neck.

The convergence yoke typically has more and smaller wires than the deflection yoke that lead to a circuit board with a lot of knobs (known as the dynamic convergence board).

There are these circular ring things on the clover. I guess those are the purity magnets? I will have to take a picture of it and post it here.

The piece Im missing is the square metal piece.

You are not missing any neck hardware if that is a current picture of your set.

The black discs in the slots near the tip of the leaves of your convergence clover are 3/4 of your static convergence magnets (the blue lateral being number 4)... the levers at the tips of the clover leaves are locking levers for the static convergence adjustments.

The black rings with tabs that wrap around the neck just behind the clover are your purity rings.

Behind the purity rings is a metal strap that is held to the neck with a spring... the little bar that protrudes from the strap is your blue lateral magnet... adjust by sliding in and out.

The blue lateral magnet needs to be located directly over the pole piece of the blue gun (That's the little metal piece spot-welded to the blue gun. The red and green guns lack this item).

That is a picture of before i bought the set. I am currently missing the spring and magnet assembly. I will need a sub

Any style blue lateral magnet (from a 21") will work. But I don't have any.

Surely someone here on vk has one off a parts set?

I'll see if I have 2... I do enough roundy work that if I only have one and I sell it my luck will be that I end up needing it within a month of selling it ...thus why I don't want to sell if I only have 1.

I appreciate that you will look. Thank you

If Electronic M doesn't have one, I might. I have a bucket of assorted ion traps & magnets up in the attic.

The CRT is a 21FBP22A.

I will say I took a chance on this set not having my crt tester when I picked it up. It tests good on my bk 467. Cut off, tracking, etc.