CurtPalme.com Home Theater Forum

[cmjohnson]

The extra set of rings (which have no color code on them or adjustment screw) are not magnetized. They will do nothing.


I've successfully turned "blank" CPC rings into fully functional 6-pole rings, done first by erasing whatever field may be in them with a
bulk tape eraser, and then applying six pairs of 1/4" diameter supermagnets to the CPC ring pair, spaced evenly, alternating polarity, and letting the mess sit for a while. A day is good. Then remove the magnets without letting them slip toward any other magnets, and you should have a good working set of 6-pole rings.

Collect all the 2-pole (flare only) and 2,4 pole (flare and astig) CPC assemblies you can find. Rebuild them into 2,4,6 pole sets after
remagnetizing the spare flare set to be 6-pole pairs.



Incidentally, the K-D magnetic assemblies consist of TWO alnico magnets (they look like metal) and all other components in them are
made of ferrite. There's a reasonable chance that a ferrite supplier can reproduce those additional rings and discs for not a great deal of
money as they're molded and pressed. They might even be stock shapes. Hope so. Then it gets pretty cheap to have them made.


CJ

[garyfritz]

[tse]

The focus mags with the "+10" sticker are from an Ampro projector. The other probably is, too. The ones with stickers have been re-gaussed from the standard strength. Ampro had a couple of different focus boards with slightly different static focus adjustment capabilities. You can only try them and see if they work.

There were no special rings that were used with either type of mag. Some were 2 and 4 pole, some were 2, 4, and 6 pole.

Scott

[cmjohnson]

The extra rings are not magnetized, but I stress, they CAN BE magnetized. Get some 1/4" diameter neodymium disc magnets and have at it.

If you wish to image the magnetic pattern on the ring, go to ebay and get a small bottle of ferrofluid and a petri dish. It's a very sensitive
way to image magnetic fields.

You can make your own ferrofluid if you wish, by letting a piece of steel wool rust in a jar full of water. Grind it up frequently and after a few weeks,
you'll have iron oxide powder so find it'll float in air after you evaporate the water from the jar. Add that to some lightweight oil and you've got yourself some ferrofluid for imaging magnetic fields.


CJ

[garyfritz]

I'll see if I can figure these things out on the tubes before I try tearing them apart to suss them out with ferrofluid or remagnetize them. With luck they are 4/6 poles and I can center by rotating the KF2211's. If they're 4/6 poles I might keep them even if I go back to the Thompsons.

So with the KF2211's, should I pull the stig board? Or just leave it alone?

[tse]

It won't hurt anything to leave the stig waveform board in place. Probably the best bet.

The rings should be 2 pole, 2 pole and 4 pole, or 2, 4, 6 pole.

Just tighten the mags on the tube neck and use the projector position controls to center the raster. Even though the control is accessed in the convergence section it is really using the deflection circuits to move the image. It doesn't overload the convergence circuits.

Scott

[garyfritz]

Really?? Hm. When I first set up my 8500 the mount was wrong, and it was shooting way high. I had to use the position controls to move the raster down (up on the tubes) to put the image onto my screen. The convergence didn't seem to be very stable with that setup. When I modified my mount so I could use a centered raster, the convergence seemed to get a lot more stable. I figured the less you had to do with the centering, the better?

[garyfritz]

I finished wiring up the FYokeI's and went to put them on the 8500, when I suddenly realized I wasn't quite sure which was fore and aft. I assume the "label" side faces aft, toward the VNB, and the side with the little compression neck and the long screw-hose-clamp-thingie (technical term ) faces toward the bell? And presumably the hose-clamp-thingie on the 4-6-pole CPC rings faces toward the VNB?

[Joust]

its hard to follow your description.

The rear end is the one that has the metal "hose clamp" that firmly clamps the yoke to the neck of the tube by clamping the plastic tabs the sit flush on the neck. you cannot go by labels because no two are the same. stickers can be put anyplace.
Did you turn the magnetics inside the shell?
AFAIK all sony yokes are 180deg out of phase magnetically with the thompsons. Its easy to check. just bring a thompson close and see if it respells or attracts.

[garyfritz]

[garyfritz]

Anyone? Anyone?? Do I have it right now?

Also, something occurred to me -- one of the reported major benefits of the Fyokes is the ability to run at much higher contrast levels without blooming. But you still have the basic limit of the blue's ability to emit light before overloading. If you run at higher contrasts, won't you have to run the blue even more defocused in order to compensate for the hotter red and green?

[cmjohnson]

No.


Your available brightness (contrast, really) doesn't change. Only your focus quality, particularly over a wider range of contrast levels.


I can run my PJ pretty darned hard and not notice any yellowing due to the blue tube running out of steam. I DON'T run it that hard, but
I CAN run it with the contrast up in the 90s without any blue output issues.


CJ

[tse]

The illustration in your previous post is correct. I think the idea being have the magnet as close to the phosphor as possible. Best position would be with static focus at 50, both picture menu and service menu, slide magnet back and forth on neck for best focus. You can leave the CPC magnets off until this is determined. If mag ends up against the yoke or 1/2" back then you are good to go. If it ends up back more than 1/2" then position it 1/2" back from yoke and see if static focus control will bring it in. If the mag has to be back more than 1/2" the CPC mags might be too far back on the tube to work. At any rate, the CPC mags should be up aginst the back of the focus mag. The magnet is the wrong gauss if it has to be too far back, same if it is all the way against the yoke and the static focus won't bring things into focus.

Scott

[garyfritz]

OK, thanks Chris. The max light output (contrast) is no different than it was before -- but now you can use it better because your focus stays good at those higher levels. But if you calibrated your projector to a max contrast level of e.g. 60, that includes defocusing the blue so it gives a good flat color temp across the IRE range. Obviously the blue is saturating at that contrast=60 level, otherwise you wouldn't have to defocus to keep the temps flat. So if we say for argument's sake that the blue starts to saturate at IRE100 & contrast=50, then you could run at contrast=50 with no blue defocus. But it's going to saturate at lower IREs at contrast=60, so you have to defocus -- but it saturates at even lower IREs at contrast=70 or 80. So wouldn't you have to defocus the blue even more to handle the saturation at lower IREs?

Thanks for the tips, Scott! So the CPC mags are supposed to be right up against the focus coil -- or at least as close as you can get them, since you do have the hose-clamp thing in the way.

[Nashou66]

This is where idividual contrast settings for each tube woulf be great to nail down greyscale and to compensate for tube iregularities between each tube.
TSE can this be on VDC's next softwear issue?

Athanasios

[Gino]

[zGman]

Greetings,

Many thanks to Terry for helping out over the T'giving weekend.
The 9500 Ultra with LUG's and 1292 yokes and HFQ900's is finally up
and running and looks great. Thought I would share a few observations:

Only needed a couple clicks of Blue defocus to get a good greyscale.
The center focus adjustments ended up in the 20-30 range individually.
I did a mod to allow the focus yokes to move a little further forward,
(removed conv coil clamp & machined focus coil housing to fit over tabs)-
this was a small gain, but did allow the cpc magnets to go back to
their 'stock' position. I also hooked up the thermistors and mounted
in the focus coil housings. Also ran the focus coil ground wires to ground.

Also found that the stainless steel clamp rings on the focus coils were
accumulating significant static charge, and considered the possibility
that a few thousand volts built up around the tube neck might adversely
affect focus, so decided to use the marquee conv coil (plastic) clamps instead.
Also grounded the clamps on the cpc magnets.

Also addded the 10MOhm resistor and spark gap @ pin 7 for the LUG's,
and drilled additional holes in the back side of the neckboard covers
for better cooling (suggested by MP).

Overall, this is looking really great and thanks again to Terry (tubes, c-elements,
and lots of help and encouragement), MP (lenses and suggestions), Graham (yokes),
and Stuart (additional ultra chassis)......!

Cheers,
Galen

[garyfritz]

Interesting, Galen! Hm, the KF2211's have the metal hose-clamp on the aft end, but they also have a plastic clamp thingie on the front end -- the 4 axial things sticking out of the top in the picture above are the handles for tightening it. Maybe I should just remove the metal clamp? The plastic clamp holds things just fine. Could probably even remove the plastic tabs that the metal clamp sits on, if moving the CPC mags up is a good idea...? The CPC mags also have a metal clamp, so if that's a concern, I could steal the plastic clamp from the Thompson coil. Seems odd that Ehome/VDC wouldn't have thought of that if the static is a problem, though...

[zGman]

Hi Gary,
I found it interesting that Barco always grounds the clamps for the defl/conv yokes
and the focus yokes.
I figured while I was in there it would be easy to ground the cpc clamp also.
The front twisty ring on your yokes is for centering, if you remove the rear tabs, you may
need to consider a method to center the rear also, but I think it's a good idea to have
the cpc's further forward, at least to where they were originally with the stock yokes.
Cheers,
G

[garyfritz]

?? Are you sure about the front twisty rings? They don't appear to make any centering changes, and the coil shell itself fits snugly on the tube neck. It seems to act as a clamp -- though not a very good one.