CurtPalme.com Home Theater Forum

[r.bauer]

First I need to say I have tons of experience with Barco's, Sony's and NEC's and just a little with Marquee's. But after fiddling with a Marquee some more last night I have a few questions about certain Marquee design choices. And what better place to ask but here, so here it goes:

- Why are the focus and astig adjustment ranges so huge? There must be a reason for it and I really would like to know. Also, if you put up dots and go from underfocus to overfocus you end up on both ends of the scale with misformed clouds that do not stay in their position, (even after doing mech and electronic astig) where a barco gives you nice round circles that do not move, on both ends of the focus scale.
- Why is there no BIAS control in a Marquee? The G2 adjusts another grid, and both adjustments can't simply just be 'swapped' as they do something different.
- Why are the cables on top of the tubes so messy? All projectors look clean on the inside, and only a marquee looks like you look under the hood of an old junk car. Anybody got a picture of a good cabling suggestion that has the cables fixed in stead of just laying around?
- I read a lot of good things about the marquee video chain, and I am sure that someone once put a lot of thought into it, but it also has noise in it like any other brand out there.
- Why didn't Electrohome/VDC use hi-res tubes in their machines. Both 8" and 9" tubes found in Marquees are low-res versions of these tubes, while Barco, Sony and NEC equip all their high-end projectors with hi-res tubes.

Don't get me wrong, the picture a marquee can display is simply stunning, but if I need to be educated more about the marquee, then tell me what I am missing. And Why are there so many Marquee mods out there? Is it because they simply need it to perform, or is it because it is such an easy machine to mod, or because it is the most popular CRT-projector in North-America because there simply are so many out there?

Thanks,

Reinier

[Nashou66]

I think the Marquee performs just as well as any other PJ out there stock even with the low res tubs the older one's had(most new use the High res tubes like my Longbow), having said that you noticed that it also has some noise just like any other PJ. So imagine if you do add the higher res tube's and clean up the noise. Bam! super PJ!!! That is why there are so many mods out there and the fact that its a simple elegant electronic design and easily lent to modification with just the addition of better parts and not so much a redesign, it has one of the coolest focus amps and the patented resonant circuit design for the different frequencies, and you get that extra range, which i think is there to accommodate all the different size and type of tubes you can throw in it. The cables are a mess from people moving them around, my new Longbow had them all nicely tucked away. I too have moved them since. The reason there are so many is the military and avionic companies love these for their 24/7 run time abilities and the fact they are so easily serviceable and easy to trouble shoot. They are just built like tanks.

The one thing I think they should switch to is the kanto denshi designed focus coil. That is the biggest improvement to the marquee and the first any marquee owner should do for image improvement. Those cols also minimize the grid movement during focus ramping..

One thing since were on the subject of the marquee design is why is the red tube so much sharper on all the marquee's i have seen?
My theory is it is furthest away from the Horizontal deflection module. I have not had time to check but I think if you look at either side of the blue and green
grid that is next to the HDM that side does not focus as well as the side not closest to the HDM. I always thought more shielding of either the Tubes or the
HDM would help.

Athanasios

[antorsae]

Athanasios - I have not observed the red sharpness issue you describe. I will re-check as I have one of my PJs with the red swapped so I'll check if my regular R G B projector's red (R) is sharper than the swapped (B G R) one.

As for the BIAS question, the marquee has the BRIGHTNESS setting which lowers/increases the signal offset for all 3 channels. In addition, newer firmwares (from V5.0 I think) have sub-gain control, which is the option to lower/increase the signal of the R G B channels independently (in fact you do G via brightness and compensate with R and B sub-bias). I asked this question in the forum a while back and the response I got back then was that the effect was the same as if you changed the individual G2 settings for each tube.

Now that I have fully automated the measurement of the transfer function of a tube using a DSLR camera I can plot the transfer curves (also known of gamma curves) and compare how a setting affects the curve. If I find some time I will see if I can do this for the sub-bias controls vs. the G2 ones.

[draganm]

[Nashou66]

Draganm. Thomas Electronics could possibly make those coils from there magnetics division, I forgot the name. But they can do it but bellows is one thing, to make coils would be 10 times more initial cost than what my bellows project would be i bet.

Ok I found the company name Syntronics, they made the focus coils for the Triton 1080HD Projector the Thomas tubes I have were used in.
Aferg was going to send me one but he said it was huge and encased in an aluminum magnetically shielded housing. No magnetic fields escaped
into the other electronics that is why it weighs 5 pounds and had a special mount so it wouldn't
put strain on the tube neck. I guess that PJ was razor sharp, just too costly to maintain and very large and is why they switched tot he Marquee.

maybe you could follow through to them with a phone call, send them the patten papers for the kanto Denshi design and see what they say.
you wouldn't need a case as we could use old barco coil cases or just wrap them in rubber tape.

http://www.thomaselectronics.com/capabilities/

Athanasios

[draganm]

[cmjohnson]

I just want to point out that the standard resolution tubes found in a 9500 (I refuse to call them "low resolution" because they're NOT!) are still quite capable of fully resolving 1080p with ease.

As for the focus coils, the Kanto-Denshi design really isn't all that tough to duplicate. It consists of easily duplicatable and measurable
coils, two ferrite discs, some ferrite rings, and some alnico magnets, none of which are that expensive to duplicate, individually, by any
custom ferrite and magnet company. The magnets can be measured for field strength and new ones can be magnetized to those specs
quite easily with a magnetizing jig I could build myself.

It WOULD cost a little to get the ball rolling on a project to duplicate them, tailored to Marquee requirements, but honestly it's far from
a complex project. All the parts are simple.

For example, I could break down a 22-22 to its components, send the ferrite parts to Fair-Rite Products Corp, and in a few days or a couple of weeks have an engineering analysis of the ferrite type use and a ROM estimate for getting the parts duplicated for a small
production run.

Do the same thing with the magnets, contacting BB Automacao, as one possible source, and get a quote shortly.

Do the same with the coil bobbins, either pre-wound or delivered as raw bobbins, depending on whether or not the coil company
makes its own bobbins to spec.

Then there's the housing to deal with, and frankly I can't see any reason not to build a better housing.

Adjustments to a few dimensions here and there would even add the ability to adjust the new focus yokes with regard to beam centering,
something you can't do with the K-D yokes now. But is it even desirable to have that feature? As I see it, the reason why Thomson
magnetic focus coils have that feature is because I don't think that the design of them lends itself to consistent and uniform field strength
distribution. The offsettability of the Thomson design is to compensate for that.

I think the K-D design is intrinsically more magnetically stable, and as you know, when properly modded, it's the demonstrably superior
choice for a Marquee.

Incidentally, I just located a 1272 that's about to get scrapped. (It's got a bunch of problems.) Needless to say, I'm getting its focus
coils. Then I'll have a spare set...to hoard or to sell.


CJ