CurtPalme.com Home Theater Forum

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Totally Understood Curt.

I know there is a thread here with that info. I think it was mixed in with another thread on tubes. Maybe the P16 tubes since they also need a pin 6 G2.

Athanasios

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Ok I found the thread,

https://www.curtpalme.com/forum_archived/viewtopic.php@t=3076.html

One thing is they go back and forth of what to do. One has it with pin 5 connected to pin 7 stating its like making a PT22 tube.

Also I think greg had a typo in his info for tying G2 to G1, I think he meant G3 to G1.

Also what Size resistor did you use? I think it should be a 10Meg not 1 Meg. In the thread Scott links a G90 Pin out diagram and notes to use a 10M resistor. As it has to do with capacitance on the Grid.

**Curt Palme** · Posted: Thu Aug 12, 2010 1:09 am Post subject:

The value shouldn't matter, it's simply tying a point to ground. I don't think the actual voltage appearing on that pin is important, only that it's referenced to ground.

I will take this further, it's bugging me now, but the only real variable between a Sony, Barco and a Marquee is the size of the focus yokes, which is why people have been playing with Frankenyokes for years. I didn't think there was much to it, but now... well.... I reserve the right to change my mind. Very Happy

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

It is weird since Scott mentioned this

Chuchuf · Joined: 11 Mar 2006 Posts: 548

**Curt Palme** · Posted: Thu Aug 12, 2010 1:41 am Post subject:

Thanks, that's EXACTLY what I thought on both counts, and the haze is what I was having issues with on the second tube that I just put into a Sony.

CIR Engineering · Posted: Mon Aug 16, 2010 11:26 pm Post subject:

Curt, what you are seeing is normal. The LUG tubes are not as bright in the Marquee as in the G90 or Barco's. I went back and fourth with a client Madrigal in which I put a green LUG. With the LUG the projector blooms at around 59 or 60 contrast setting with the gray at proper D65. The LCP's usually bloom there as well, but at a 60 contrast the LCP is much brighter than an LUG (confirmed with my PR650). Because of this, the Marquee will not run as bright with an LUG as it did with an LCP. It's a trade, you get a sharper image with the LUG, but a brighter image with the LCP.

Mike P even sent me a 909 coil that I hooked up to the LUG in the Madrigal. Even after trying everything with the 909 coil I still did not get much better focus at high contrast... and I mean everything. I literally put at least 30 hours into trying to tighten up the focus at higher contrast.

In the end, I went back to the stock Marquee magnetics. What helped get the least blooming with the brightest image was to be absolutely meticulous with the magnetic setup. I found the tighter I got the magnetic focus, the less blooming I would see at high contrast.

MP just sent me his newest VIM and VNB's. When I was at Mike's place the last time he showed me that with his new VIM he can run the contrast at 100 on the Marquee with zero blooming. I will be installing these boards in said Madrigal as soon as I can get out there and I bet when I do the LUG will be sharp at even very high contrast levels.

BTW when I was doing all this I talked to Scott a few times for advice. He told me the same thing I found. The LUG's are sharper, but not as bright as the LCP's and that is just how it is in the Marquee machines.

My client with this Madrigal and I both have STK130 screens that are 96"x54" (identical screens). On his Marquee I measure about 8 flt with a 100 IRE window. On my G90 I measure 13.5 flt on a 100 IRE window. The G90 can just maintain better spot size at high contrast with an LUG when compared to a Marquee with an LUG. This is also why the G90 can rip through tubes so much faster than Marquee machines usually do.

craigr

**Curt Palme** · Posted: Mon Aug 16, 2010 11:40 pm Post subject:

OK, that is pretty much confirming what I see here, and counters those above that countered me. Smile

The question that remains then is... WHY?

Why does a LUG work fine in a G90 and a Barco 1209s/909/Cine9 without blooming and defocusing? It's something in the Marquee causing this.. I don't want to believe the HVPS sags with a LUG in the set, as the R and B would defocus...

I still think it's something that can be overcome.

The other LUG in the Marquee housing is now on the way to me, should be here mid week. I'm a bit behind, but will spend some hours (not 30!) working on this to try a few theories..

CIR Engineering · Posted: Tue Aug 17, 2010 12:05 am Post subject:

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I am not sure but i remember Scott saying something in an Ampro vs Marquee argument that ampros focus better and have slightly higher light output due to using a higher voltage of some sort on the output amps or neck boards. I think it was cut off voltage.
I'm not 100% sure but could this have anything to do with it? Isn't there a trim pot on the VNB that adjust cut off voltage that has
glue on it and set at the factory for the tube type it has, could this be that voltage I am mentioning.

My theory could be totally wrong but I remember that discussion.

Athanasios

tse · Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.

I had forgotten about that but you are right. The Marquee chassis uses +/- 85V for the amplifiers that drive the cathode and G-1. That means that cut-off (largest difference in voltage between the two) can at most be 170V. In practice it will be less for some blanking. So cut-off could be running at 160V or even less. The CRT design cut-off is 180V. G-2 will be set lower than design goals to achieve cut-off. The price you pay for video bandwidth.

Scott

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

tse · Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.

The reason for +/- 85V is because of the neck cards. Running them with higher voltage might be unreliable. Poof more often.

Scott

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

What about the new style cards? Can they be made to go to that +/- voltage for LUG's?

Athanasios

mp20748 · Posted: Tue Aug 17, 2010 1:38 am Post subject:

mp20748 · Posted: Tue Aug 17, 2010 1:43 am Post subject:

macgyver655 · Joined: 22 Aug 2007 Posts: 8508

CIR Engineering · Posted: Tue Aug 17, 2010 2:16 am Post subject:

**Curt Palme** · Posted: Tue Aug 17, 2010 3:01 am Post subject:

tse · Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.

It's the poof of performance.

Scott