CurtPalme.com Home Theater Forum

[1031]

Hello. I had finaly some time to install those 1292 sony yokes to my 9500lc. Yep much more thigter spot and more usable contrast now
But i miss that magnetical rastercentering that those thomson yokes had
While 1292 yoke shifts raster when turning it, it doesent give good enought results, i had use too much electronic centering (that firts point of convergence..)
So i think what about using one 2-pole set for rastercentering? There might be just enough room for 2-pole magnet is clamp for convergence yoke is removed

I have never understandet what is difference between 2-pole and rastercentering magnets (ok those are at different places at tube neck and therefor do different things). I had some yokes from Es-focus seleco and those had raster centering magnet rings before convergence yoke so i tested if i put 2-pole rings near marquees convergense yoke and see how it works.

It works But i havent tested that yet in my main machine yet

Experts what do you think can 2-pole ring there (between focus yoke and conv.yoke) still affect to beam shape?

Some pictures...

[1031]

Here is picture where i thinked to put that 2-pole set

[Nashou66]

It could work jarmo, but see the clamp you have there now for holding the convergance magnets. I took that out when testing and reamed out the center edge of the 1292 so it fits over where the clamp is. this puts the 1292 closer and also give even more focus. i used a round edged file to make more larger diameter inside of the 1292 yoke. , My centering wasnt too far off with them either. But your idea is kinda cool.

Athanasios

[1031]

I sanded that clamp so its about 2mm thinner now..
Here is some pictures, i tested that quick and that 2-pole seems to work ok for rastercentering (tested with marquees stock focus yoke)

[Nashou66]

Nice Jarmo. If i have trouble with raster centering i'll dot he same. However I am a bit away from doing anything for now. But looks like a great idea. But try to do the same to your 1292 coils inside to fit over convergence ring and not put raster centering ringson. you might solve problem that way. I dont remember raster being too far off to need those rings, but if you do need them its a great great idea!

Athanasios

[tse]

Nice mod!

Scott

[1031]

[Nashou66]

When i pushed the yokes as far forward as i could i got a bit better focus, but i never had a bad raster shift. I did have to turn the yokes all that around to move the raster to the center. One thing you can do and i tried it this way the first time is to not have the plastic housing on the focus assembly. I used just the bare magnets for my first testing then put them in... but i did notice if i turned the magnets around i could move the raster, and if i moved each ring in the structure some it move it even more. But this can be dangerous as if you move one ring to much you might deflect the beam out the side(this is only theory from what CMJ and I think TSE mentioned this too). I had the whole assembly wraped in rubber tape too when i had no housing on it. I was thinking of doing it this way
and gluing the magnet in place, this gives more room to move the CPC magnets closer to the focus coil if you need to. Hmmm.. maybe another centering ring before the focus coil could do the same thing ? How are the CPC mangnets lined up towards the Focus yoke? Icant remember off hand. is it 6,4,2 or 2,4,6?

Athanasios

[1031]

Magnets are from vnb-> 4-/6-/2-pole -> tube front.
I flipped that magnet assembly 180degrees inside sonys housing( that´s why that http://www.curtpalme.com/forum/files/frankenyoke_casing_mod3_294.jpg picture shows that little noch that i made). That looked best on my testbench, when i tested stock 1292 yoke (magnet assembly as original position) then raster was not horizontal..
I think that raster centering is best to do after focus yoke. Then that centering field (in theory) cannot affect beam shape so much Least all projectors that have passive centering system (rastercentering rings) those are placed before convergence/deflection yokes

[Nashou66]

Yes, you can flip the yokes but then i am wondering if the static coil vs the dynamic coils are in the wrong possitions. I think it is actually better to rotate the Deflection coil and leave the 1292 yoke as is so its the Static coil>dynamic coil> tube. My theory is that the static coil does the rough focus and the Dynamic
takes that rough focusd and fine tunes it especialy on the edges. what do you think?

So the raster centering is closer to the neck board or tube face , what do you think would work best?

Athanasios

[tse]

Two pole magnets are used for raster centering when between focus mag and deflection yoke. The same two pole magnets are used for beam centering (flair) when located behind the focus mag. This looks like it is on the right track.

Scott

[Nashou66]

Jarmo, I am glad this helped give you more control for the Thomas Tubes, well lets hope it does!!

Athanasios

[1031]

Yep. Usable contrast range is now up to 75, max was before frankenyokes at 60. Picture is still desent at contrast 80-90 but that 75 there is no blooming at all.
I have to test boht methods, yoke as original and pushed more forward / my diy rastercentering.. I must see when i have time to do more testing.

[1031]

Hello. Its near midnigth here.. i have spendet whole evening in "magnetland"
I tested every possible configuration how those 1292 yokes could be installed

1. stock orientation, conv.yoke clamp removed and focus yoke pushed as forward is goes.. Best center focus at 24 ( in service focus adj.) picture focus was at 50 all time. Rasters of about 30 degrees and side focus there seems to be enought range to proper focusing.

2 coils flipped 180degrees inside sonys housing. clamp removed and yoke as forwed as it goes. Rasters horizontal, best focus at 21 and side focus range is ok.

All those had rasters too much off center.

3 Stock orientation, my diy raster centering magnet at place of convergence yokes clamp.. rasters of same 30 degrees.Best focus at 26.

4 coil flipped 180 degree and diy raster centering ring in place of conv.yokes clamp, rasters near horizontal (maybe of by 1-2 degrees) best focus at 19-21
Best part. raster centering is easy as.. well lets say riding bicycle and it doesend affect flare setting near at all. also very little 2-4 pole adjust is needet. There was still very little raster shifting when ramping focus up/down but all colors moved similar.

So those 1292 yokes when turned around tube neck move raster, but in my case those just made "circle" around point where i wanted raster center to be, with that diy rastercentering ring that was so easy.. I was able to center red/blue over green so good that only 2-4 click´s electronic adjusment was needet.

[garyfritz]

[Nashou66]

Nice Work jarmo, you did the same testing i did except i did not have the centering magnets. I plan to make those with some old CPC sets I have.

Gary I still need to do more testing on the Barkenstiens. I got another gauge wire i did not test yet. its a thicker wire so less resistance and i can still fit it on the bobbin according to my calculations. TSE told me less resistance in the static coil will give a bit more range and let the Amps not work as hard .
Also the very first Barco coil i tried did not have that good a dead focus(no current) as the second full set i got. i have one more full set coming in this week I hope. I want to see if the dead focus is consistent. The Barco magnets actually focus better dead than the 1292's do dead, its the windings that are not even close. I also never wired up the Astig magnets on any of them so i want to test them with those connected as well. But I am not sure how far off
I am from deciding if i can go into a production mode for these. I first want to get the blend done and have started on that last week.
I also think the 1292's might benifit from winding as well, i have a spare i may play with in that respect. Maybe after I make a set i'll send them to you to have another person test them.

Athanasios

[1031]

Here is little more project pictures. Only thing that is little worrying is that i have to use max/min values to side focus to get best focusing. Example Green needs to push up to 100 and seems that if that ajust has more range, that could give tad better results. Maybe tweakin values of those "resonant caps" at FCM is what is needet to get more side focus range.

I used glass cloth tape to secure focus yoke in place, so that it fits perfect and connot move at all.

[Nashou66]

I wonder of you take out centering ring if edge focus improves?

Athanasios

[1031]

[tse]