Differences in Marquee Focus Yokes?

I've noticed that the internals of the Marquee focus yoke is sometimes different. Like my current 9ultra has the original red tube assembly and two new OEM tube assemblies.

The original red has a nice, small spot size. While the new OEM blue & green have a much larger spot size (yes, I've somewhat adjusted magnetics). In attempting to diagnose this, I've noticed that the focus yoke on the original red tube has it's internal windings protude further back than the internal windings of the OEM replacement blue and green.

Dragan, it's one of the tubes from that big auction awhile back. Came complete with all the magnetics & plastic covers etc.

I've gotta digest what MP just said above. Though I did move the scan yokes as far forward as possible, then left just a couple of militeres of movement for the focus yoke adjusting. I didn't really go all out on it to see if it could be moved further.
Heading out the door now and will tackle this later.

The attached pic shows the difference between the red windings and green windings. It's a pretty clear difference!

Wow, I had no idea there was a difference between the 9000 and 9500 tube assemblies!
These were in fact the Salt Lake City tubes, and came with instructions for installation into a 9000. hmmm is right!

And to think that I sold off all my used 9500 tube assemblies. In fact, some of them were practically given away.

Verified... there is definately a difference! I pulled the newer focus coil from my
red tube and swapped it over to the underperforming green tube and right away
my spot size got smaller!!!!

Prior to doing this, I took apart the two focus coils to see if there really was a
physical difference and there was. You can see the guage of wire is different.
Also, I measured and saw that the newer coil has more height to the winding.

[older coil on left, newer coil on right]



I was also curious as to how the focus coil is really supposed to be adjusted. This
always kind of confused me as everyone describes the procedure a bit
differently. The outer lid is basically 100% plastic. It merely serves the purpose
of holding the focus coil stationairy to the tube neck. And you can see the
difference in size between the wingnut bolt holes on the lid vs the body of the
focus coil.




Here is a better view of how the body of the focus coil is adjusted, while the outer
lid simply clamps onto the tube and is stationairy.



Here is the difference between the older (first pic) and newer label:





And afterwards I noticed this in the Marquee Training manual where it discusses
the basic changes from 8000/9000 to 8500/9500 models:






So if anyone has a couple of the newer Focus Coils (yokes) for sale, I would
definately appreciate first shot at them.

There must other significant magnetics differences as well, because the vertical height of my red 9500 CRT is much smaller than the 9000 series blue and green CRT's in the same projector. Even with convergence zero'd out and vertical height's set to 50 each.

Curt, thanks for checking though. Plus I didn't realize new focus yokes were only $50. I remembered that the deflection yoke is incredibly expensive and assumed the focus yoke would be expensive as well.

Mike, moving the focus yoke as far forward did help to achieve better initial focus... even though it was only about a milimeter that I was able to move it up. Thanks.


Ralph, the simple way to find out is to go into each of your recalls and set the focus (Pic, 4) to a different number and save. Then go back into each of your recalls and see if the focus number is still different in each recall. Btw, what Mike mentioned only applies to focus (Pic, 4)... it does not apply to the Service Focus.

Mike, your middle number seems as it would be compared with my third number.

N/S on oldest is___194 E 9
N/S on mine is____125 H 9
S/N on yours is__00236 K 5

The pattern seems to be the 2nd to last character. "E" being the known oldest, "H" being from year 2001 (my Ultra) and "K" from your current date VDC. Can anyone confirm this theory?

I wonder if there is any significant difference between my year 2001 focus coil and Mike's current year focus coil.

TSE, thank you for the info. It doesn't sound like there is any difference between the later model focus coils. Nothing to effect video quality or spot size anyway.

Btw, I swapped old vs. new style convergence coils today (red to green) and there was no appreciable difference. As far as I can tell, if anyone has an older 9000 style complete CRT tube... the only thing to change over to newer would be the focus coil. Nothing else probably matters.

Best I can tell, the two D9's are fairly old while the FD is "I don't know". But I suspect it's newer than the D9's.

I think the [alphabetical] + [numerical] is an indicator of how old the model is. Like A1 would be older than A9. And Z9 would be the newest.

The D9's are 8000 or 9000 style focus coils if the schema mentioned above is to be believed. I would suggest you compare them with the FD or higher # to see how much tighter the dots get.

The coils that I started this thread over came on complete tube sets for the Marquee 9000, as per the directions in the box that it came in. There was no mention of 9500LC anywhere on the directions. And the coils did have the stig windings, though I never thought of this until you mentioned it.

So these may have been for very early 9500LC's. In either case, when I upgraded to newer focus coils, my dot size grew noticeably smaller.

This could be due to revisions, or perhaps renewed magnetic strength. I'm not sure. But I'd suspect it has to do with improved versions of the focus coils!

Btw, how are ya doing these days, Bruce? I don't see you on the board as much as in the last couple of years or so. Actually, seems that ever since the big FL hurricanes, you've nearly dropped out of sight!