CurtPalme.com Home Theater Forum

htguy1 · Joined: 30 Jul 2008 Posts: 99

Hi,

So I am getting back into modding my Marquee since it still is just about equal to any of the digital pj's I have seen.

Some time ago I bought a set of KSD26 coils (I believe these came from a G90) Has anyone gotten these setup and working on a Marquee? I recall there was some issue with them working correctly with the astig board on the Marquee.

Thanks

God bless...
mark

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

G90 coils are huge. To run them at all you'll have to run them naked, out of the housings.

I had one to work with for a brief period of time (measurements and tests) but didn't actually run it on a tube so I can't give
you much information. It's also been so long that I'd have to find the notes I made on it.

I do recall that my opinion is that it was such a specialized design that I felt it was going to be impractical to make them run right in a Marquee.

I believe to this day that optimized Frankenyoke Mark IIs are the best possible solution. However, I sort of abandoned the
project BEFORE I had built a truly optimized set. First I had to get the static magnetic field strength set to ideal strength,
and then I found that the theoretical ideal coil winding values were actually overwound due to the efficiency of the K-D yoke design. I think I had established that static and dynamic coil values should be 30 and 5 mH in order to optimize performance for 1080p-60Hz but in practice I had to take windings off the coils to lesser values. I attribute this again to the efficiency of the design.

The characteristics of the ideal focus yoke are:

Preset all focus settings to 50. Service menu focus included.

You get good central focus and reasonably good edge focus with the yokes unplugged OR with the yoke plugged in with the dynamic coil disconnected.

You get sharpest focus with a focus setting of between 40 and 60. If you can't, odds are that the static coil is overwound. Take off five turns of wire and retest.

The significant test, to see if the coil is overwound, is to set focus to 50 and THEN plug the static coil in. If focus shifts a LOT, then the coil is overwound. Pull a few turns off the static coil.

With the dynamic coil reconnected, edge focus should not shift much. But you should be able to get the edge focus as sharp as the central focus. If you run out of adjustment range before achieving optimal sharpness, the dynamic coil probably needs a few turns taken off it.

The dynamic coil is the one that has fewer windings on it and the lower value.

And now for the toughest news: None of this works right if the magnets in the coil aren't delivering the proper range of magnetic field strength. It is something that can only be properly tested or adjusted with specialized equipment.

But, generally speaking, if your donor yokes are in good shape and have not been knocked around, they should be about right as far as that is concerned. If the static focus with the yoke unplugged is significantly different between one yoke and another in the set, then you may have this issue to contend with.

I know of ONE place where the yoke magnetic strength can be measured and adjusted.

htguy1 · Joined: 30 Jul 2008 Posts: 99

Hi.

Thanks for the input. Anyone have pics and descriptions of how to mod the g90 coils to work?
I figure I have them so why not put them to use...

Thanks

htguy1 · Joined: 30 Jul 2008 Posts: 99

I'm still looking for help getting these G90 yokes setup as Franken yokes. Anybody have pics and wiring directions???

redfox001 · Joined: 16 Mar 2009 Posts: 2251 Location: The Netherlands

Look in the Frankenyoke thread for wiring but nobody got them to work as cmjohnson explained.

koldby · Posted: Sat May 23, 2015 10:01 am Post subject:

redfox001 · Joined: 16 Mar 2009 Posts: 2251 Location: The Netherlands

At the end. I repeated all material for the 1292 frankenyokes.

koldby · Posted: Sat May 23, 2015 10:50 am Post subject:

cmjohnson · Joined: 03 Apr 2006 Posts: 5180 Location: Buried under G90s

Sorry, I can't fix the original thread's lost pictures. I seem to no longer even have the originals, or haven't found them.

koldby · Posted: Mon May 25, 2015 7:36 am Post subject:

redfox001 · Joined: 16 Mar 2009 Posts: 2251 Location: The Netherlands

You can figure it out for any crt. Look at the focus schematics and look for dynamic focus and static focus. Barco calls it horizontal and vertical focus. Than you have a high and a low wire. You can try both ways to find the best adjustment range. Than you have some earth wire that is to get the static charge that builds on the coil away in a save way. So if you have schematics for the focus board it is doable to find the wiring.

koldby · Posted: Mon May 25, 2015 12:35 pm Post subject:

Ok
Thanks redfox