CurtPalme.com Home Theater Forum

Heywood Jablome · Joined: 12 Mar 2006 Posts: 1542

Heywood Jablome · Joined: 12 Mar 2006 Posts: 1542

As a 'Fast and Dirty' first test I left the 1208 CPC pack intact (therefor expected overlapping fields) and slid the probe in and out (bow chicka bowwow Razz

) until I hit a max field, then turned each set of rings.

Predictably, the dead rings did nothing.
The "tube end" ring had four distinct lobes (that is, +/- field transitions,) and max gauss was measured at just under 10 gauss when manipulating the 2 pole rings' relative position (each half of the 2-pole relative to the other, that is.)

The setup was X&Y sensors co-planar with the rings, and Z axial to the centerline of the rings (aka "electron-beam eye's view.)
It was the X&Y that measured excursions of field strength, as predicted above.

outwest · Posted: Mon Sep 29, 2008 6:45 pm Post subject:

That is a fantastic setup. Very nicely done!

I still don't think I understand the basic function of astig adjustments. Is it to correct focus of the beam at different tube face locations or is it to correct geometry of patterns painted at different tube face locations or does it somehow do both?

Heywood Jablome · Joined: 12 Mar 2006 Posts: 1542

Nashou66 · Posted: Mon Sep 29, 2008 9:04 pm Post subject:

Very nice work! So now we all want you to make that dead magnet alive with a 6 pole arrangment, see which way works best:

This way to magnetise them

Or this way:( not sure if I have the polarities correct for this though)

Athanasios

Heywood Jablome · Joined: 12 Mar 2006 Posts: 1542

Heywood Jablome · Joined: 12 Mar 2006 Posts: 1542

Oh, and FWIW I'd probably do a little "bandsaw engineering" with some nice permeable steel... make a "c clamp" like fixture just wide enough for the ring plus two magnet thicknesses, and fasten those two magnets to the insides of the throat with opposite poles exposed. This will make a complete magnetic circuit and will greatly concentrate the resultant field thereby making the magnetized portion of the ring MUCH more concentrated too.

tse · Joined: 03 May 2006 Posts: 1005 Location: Sweatbucket, Fl.

Very interesting stuff. I would like to know how to make 2 pole rings for beam centering or just plain old raster position. I played with it a little bit but don't think the equipment that I have access to is right for charging rings. It works fine for focus magnets.

Scott

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

I have a question. Tim in Phx states that certain Marquees had 2/4/6 cpc magnets and shows some Marquee cpcs on his site. Tim does not specify which of the three sets pictured is a 2/4/6 set and the one in the middle looks a lot like the one voodoo posted a picture above. My question is, how can you tell and doesn't this mean that there are some 2/4/6 sets floating around used?

Here is a copy of the picture from Tim's site:

PaulB · Posted: Wed Nov 05, 2008 10:15 pm Post subject:

You see the things that look like prongs sticking out of the CPC sets? From left to right, the first CPC has one, the second two and the third three. Those prongs indicate that the ring set it is attached to is an adjustable magnetised ring.

The generally accepted common standard for these is that the number of adjustable magnetised ring sets indicates whether the CPC is 2 pole, 2/4 pole, or 2/4/6 pole.

The first CPC set has a magnetised ring set and then a blank magnet ring. Thats a 2 pole (or 2/- if you prefer)

The second has a magnetised ring and then a blank and then again a magnetised ring. Thats a 2/4 pole (or 2/-/4)

The third has three magnetised rings, thats a 2/4/6 pole (or guess what, a 2/4/6)

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

So, is it worth changing two poles for four poles?

Nashou66 · Posted: Wed Nov 05, 2008 10:44 pm Post subject:

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

I happen to have the four poles on a set of tubes I own.

For now, I'm working on the electronics. I then plan to swap in the 9" tubes (got my Red C element in and my glycol changed). I was thinking I might defer the magnetics until I got all that done. Given that I have the four poles, and am swapping tubes, however, I may put the four poles on the 9" tubes.

Where does one look for 6 poles?

PaulB · Posted: Thu Nov 06, 2008 4:00 pm Post subject:

You might not need the 6 pole set, 4 pole is obviously an improvement over the Marquee's existing 2 pole and by all accounts few marquee owners really need the 6 pole at all but this will vary from pj to pj. If you can get them it may be worthwhile but 4 pole should do you nicely though.

You'll know if you need 6 pole if your blobs look like triangles (or guitar picks as someone else described) when doing the Astig.

You can try emailing Curt first or keep an eye on EBay.

Ohmess · Joined: 11 Sep 2008 Posts: 242 Location: Vienna, VA

Thanks Paul. Your comments are very helpful.

I am going to swap the four poles onto the 9" tubes before I install them and then see where to go from there.

PaulB · Posted: Sat Nov 08, 2008 4:05 pm Post subject:

Is this how the magnets would be placed (roughly speaking of course)? Either side of a double cpc ring, an equal distance from one of the tabs?

Nashou66 · Posted: Sat Nov 08, 2008 4:56 pm Post subject:

thats how i think it should be done but have one polarity on the top and under have the other polarity, then repat with the other magnet for the same ring.

Nashou

Nashou66 · Posted: Thu Nov 13, 2008 7:49 pm Post subject:

tse · Joined: 03 May 2006 Posts: 1005 Location: Sweatbucket, Fl.

I started a new thread about this.

focus magnet charge/discharge

Scott

cmjohnson · Joined: 03 Apr 2006 Posts: 1677

Sorry to resurrect a dead topic, but I have a box full of CPC magnet sets and I've done some SUCCESSFUL experiments with taking blank ring sets, and even functional ring pairs, degaussing them, and then regaussing them in the desired 2, 4, and 6 pole configurations.

I use a magnetic viewer sheet to visualize the rings before and after and compare them to a factory set.

The process really isn't hard. Get yourself six pairs of 1/2" diameter neodymium magnets and make a clamshell fixture for them, with six magnets on top and six magnets on the bottom, with the CPC ring positioned inside the clamshell fixture. Be sure the magnets are staggered magnetically, so any two are trying to attract the nearest one. Refer to drawings above on this page. Place the ring in the fixture, close it (I'd put a hinge on one end of it), and let it sit
for at least a few seconds and then open the fixture and remove the CPC ring by pulling it straight away from the magnets, without any swiping motion
to alter the fields.

To make a flare set, you'd use two pairs of larger magnets.

To make an astig set, you'd use four pairs of medium sized magnets.

To make a 6 pole/triangularity set, you'd use 6 pairs of small magnets.

I have a good sized box full of donors and parts candidates. No doubt Curt has even more if he hasn't been tossing them.

CJ