CurtPalme.com Home Theater Forum

[antorsae]

Athanasios - You are just amazing!

[Gino]

I agree, well done!

[radar]

Totally interesting thread. What concerns me is a benchmark for focus sharpness. I'm still setting up my Marquee 8500 and its lookin pretty good.... but could be sharper. How can I tell if I've got them as sharp as they will go? And how much sharper will these mods get me? So... I propose a test so we can all be on the same page. My 8500 has as lense mod so I have HD-144 lenses. My screen width is 2.1m (7'). Theoretically, a one pixel line from top to bottom should be about 1mm thick using a 1920x1080 source (or 2mm thick using 1024x768 source on the same width screen). To cater for different screen sizes, a 1 pixel line should be about (screen width/1024) wide using a 1024x768 source.

So, to determine a stock 8500's sharpness, what width should I expect a 1 pixel line be? I'd say mine is about 3mm using a 1024x768 source. So do I still have some tuning to go? If have a PC capable of displaying 1920 x 1080, could I expect a 1 pixel line to be 1mm thick with the appropriate focus mods?

Is there another way to benchmark sharpeness so we can compare our pj's against them?

Cheers,

Kevin.

[Nashou66]

[1031]

Athanasios, here are pictures from those yokes that we discussed. I havent opened those yet but inductance seems to be too low that those work on marquee. Also that yoke is not so long that KF22-22 is ( no stig windings)

[Nashou66]

Those look like an ampro Yoke. You can test the magnet stregnth on a tube with no connection tot he coil. if it has some focus like the picture further back of a red grid i posted it can be rewound to work in a marquee with no astig amp and get better results than the stock coil. The Yoke from Nec's and G70's are similar also but have a smaller diameter plastic bobbin. Does anyone have the diameter of those smaller necked coils?

Athanasios

[1031]

Those came from Ile´s Barco 1200. I test those later..

[Nashou66]

[Nashou66]

Hello Gentlemen, I decided t try the Frankenyoke and the Barkenstien in the PJ on the Green 8 inch Tube( no astig coils hooked up yet). Looks like a VDC rebuild by the Brown neck(no wonders I couldn't get a good focus all this time), anyways..... I first looked at the stock coils then went to the Frankenyoke, then the Barkenstien. These VDC rebuilds do suck compared to the test green just from looking at the tube face i can tell, but since this is the same tube for all yokes i can still make an assessment of changes. The Frankenyoke is step up for sure from the stock coil, and you do need to rotate the coil assembly inside the yoke for a level grid. Then I added the Barkenstien yoke , just a little better than the Frankenyoke, I think the rewinding of the static coil to be closer to stock(still off by 5mH) is what helps the Barkenyoke go ahead. I am having a slight issue with left to right focus when going into the Zone focus. When I adjust the edges for a better focus the center goes out a bit, I can get a compromise but tis just the same as a stock yoke then. I think if I get both Coils to the exact same values as the Stock coils I'll have better results, or maybe going to a larger wire gauge say from 32 to 30. At 30 I should have enough room for the wind. The Dynamic I have now measures 60uH and it should be closer to 45uH and a lower resistance I'm about .5 ohms to high, also the resistance for the Static is a bit too high as well so a larger wire will help lower that or unwinding to the 29.6mH from the 36mH i now have. So right now as I have them I would use them as they are still better than the Thompson yokes even with the edges off ever so slightly. On a better Tube I am sure they would be better. I tried to take pics but the point and shoot camera i have can't focus correctly using it auto focus and there is no manual, Plus I think it be hard to get a good pic of it.
Also I need to do the astig on it for a perfect test, but each coils may need a different astig set up and I dont have extra CPC magnets to do it for all three.

I like what I see and I think I might wind a frankenyoke static also or just swap on in from the Barkenstien, but getting those magnets apart and feeding the coil leads through the slits in the magnets is not fun!!! thats why I have not rewound the coil i have now to 29mH's.

More testing to come.

Athanasios

[Nashou66]

I think I might know what will solve the edge focus issue on these. When I first took apart the coil assembly last year i forgot which end the static and dynamic coils were in relation to each other in the magnet pack. I was thinking about it all night and had an Ahhhhaaaaaa!! moment. The dynamic focus is used to correct the side focus of the static
magnetic field and of the electromagnetic static field. So the static coil should be first in line for the electron beam to travel through, then it would pass through the dynamic electromagnetic field to "fine tune' the left and right sides to match the central overall static field.

So i will need to take that assembly apart and swap the coils inside or swap the whole magnet and just level the deflection yoke which might be easier since i glued the wires into place as they are very thin an delicate.

Also can anyone who has a set of frankenyokes take a pic of your static dead(not connected) focus of the larger internal grid. i want to compare it to the static dead focus grid of my Frankenyokes..... I may have found something interesting with the dead magnetic field , but I want to make sure its not with my coils only.

Athanasios

[antorsae]

Athanasios - isn't that equivalent to just leaving the center focus (static focus) at 50?

[Nashou66]

[DGP]

[Nashou66]

I copied my reply to a PM DPG and am posting it here as it is a response to the above post ,
I still would like a picture of the Grid from an non connected Frankenyoke as i
need it as a confimation to my own testing , I'll let you know why later.

[DGP]

First of all Merry Christmas to everybody.

Finally I received the set of KD 2222 focus yokes, but I have some doubts about how to install them. My options are:

1- Open the focus coil housing and rotate the complete magnetic 180º. Most of the people here did this, but in this case the position of the static coil and the dynamic yokes will be reversed compared to the Thomson coils. (Static closer to the bell and dynamic closer to the VNB).

2- Install them as they are and rotate the deflection and convergence yokes, but this could have side effects because of the reversed magnetic field.

Anyone here installed the yokes in this way? Any side effect?


3- Open the focus coil housing and the open the magnetic rings, swap static and dynamic coils inside the magnetic rings and then place the magnetic rotated 180º (this will have exactly the same coils and magnetic field orientation/position than the Thomson yoke).

Also a friend recommended not to separate the magnetic rings, because they could lose some strength.


Any help will be appreciated.

DGP

[Nashou66]

[Ohmess]

Hi Gang – I pulled the focus coils out of the Sony 1292Q I purchased last week, wired them up and got them into the Marquee. I’m still working on setup, but so far it is looking very nice.

Anyway, I thought I would toss in a couple of things I did just in case others may find it helpful. First off, buying an entire Sony 1292Q was cheaper than buying just the focus yokes. Luckily I found one local, and for the price of a couple of hamburgers got some muscle to help me get it home.

The yokes were Sony # 1-452-811-11, but the other numbers did not correspond to anything in this thread. I’m not sure the other numbers (K22-22) are helpful to those looking for the proper focus yokes.

I drilled out the rivets holding the housing of the Sony focus yoke together, and spun the magnets 180 degrees in the shell. I then used the brass hardware from the Thompson yokes to put them back together. I had some difficulty replacing the wiring board, and decided to remove and resolder each of the wires to the opposite side of the board. This allowed me to put the board in using the original orientation.

In wiring them up, I decided to retain the Sony wiring harness, and to splice this wiring into the convergence and astig wiring from the Thompson yokes I removed from my projector. The coloring from the Sony harness did not correspond to the picture earlier in this thread. Attached is a chart showing my harness wiring.

Raster centering was not a problem; I did not have to rotate the focus yokes at all to get a level raster.

Cheers


2009 Update: My original attachment was incorrect. A corrected version is attached.

[Nashou66]

[Ohmess]

I thought about that, but it was not entirely clear from this thread that others have gone this route. It seemed the consensus was to rotate the focus coil in the housing.

What do you anticipate the benefit from this orientation would be?

[Nashou66]

better edge focus, should be the result.

Athanasios