CurtPalme.com Home Theater Forum

**Curt Palme** · Posted: Mon Sep 26, 2016 6:22 pm Post subject: Revisiting LUGs in 9500s

Here's one for you. I had a similar thread years ago, but thought I'd do this again, as I ran into the same problem, so here goes:

I purchased a bunch of 2010 vintage 9500 Ultra projectors last year. Two were NOS, and two were used, and I'm assuming high hour units, which I'd guessed correctly, they were. Sadly, the one NOS set showed up smashed, necks snapped on the NOS LUGs. Evil or Very Mad

One high hour Ultra got smashed as well, the other was fine, but the tubes were toast.

Since the chassis were OK, and I've had a run on sales in the last month, I decided to drop in some new LCP tubes and the old style neck boards into the sets that needed tubes.. At the same time, I received an older 9500 non Ultra where the seller had dropped in LUG tubes. His tubes were OK, save for glycol discoloring, which I changed.

So, converting two 2010 sets from LUGs to LCPs was uneventful, everything worked fine, and they went out the door. I was then out of good used blue tubes. Before I bought some blue LCP tubes from Tim, I wanted to see if I could mix LCP tubes and the one blue LUG. I found out a few things:

You cannot interchange the new VDC 2010 neck boards with the old original 50-2039 neck boards. For some reason the new style neck board mutes out the two older style boards. I haven't gotten into that, but does anyone know why this is?

I then put on an old style 50-2039 neck board for the LUG, switching the g2 pin from pin 2 to pin 6. The tube fired up, but I had horrible focus. This is what I'm stumped on. I did find a point around 20 or so on the focus range where I got best focus, but I had flaring all around the crosshatch and/or dots. Crank the focus up, and it got worse, a lot worse. It was almost like someone had completely misadjusted the astig magnets, but that wasn't the issue. Turn the focus down below 20, focus got worse. turn it up over 20, and it also got worse. So here's what I tried:

-switch focus yokes over to the 2010 version
-change and reset astig magnets
-ignore the fact that the 2010 neck board killed the video on the older boards, I concentrated only on the blue tube. Even with the 2010 neck boards, it looked terrible.
-connected and disconnected the unused pins to ground, as the newer 2010 neck board does with a jumper. No difference.

The one thing I haven't done is switch LUG tubes. I have a very worn simulator burn LUG sitting here, the only one I havem't scrapped, so I will drop that in over the next couple of days.

Thing is, I had this identical focus problem with a brand new LUG I got from Terry years ago, where I couldn't get good focus on the green tube.

Somewhere I'm missing something. Can you not mix LCP and LUG tubes? That doesn't make any sense to me.

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

This is going to be fun. We know that the LUG tubes add a third grid and the internal geometry of the other grids is somewhat different.

I myself have not encountered the problem you describe here. I've swapped LCPs and LUGs around in my test chassis with wild abandon and I'm just not seeing any dramatic differences other than LUGs being sharper and they show scan lines easily with less precise magnetic adjustments.

As per VDC's own documentation, there are two major styles of "new" VDC designed neck cards.
The 21771 style card is NOT compatible with the "classic" (0338 and 0339) cards. DO NOT mix a 21771 series card (as printed
on the board itself) with the classic cards.

If you run a 21771 card, you must run THREE of them. They are only compatible with themselves.

The 270340 style card IS intercompatible. (Board markings also identify the board as a 65518 type)

So Sayeth VDC. I have the document. And here it is.

barclay66 · Posted: Mon Sep 26, 2016 6:55 pm Post subject:

Hi,

I did mix LCPs and LUGs in my 9500 Ultra with acceptable results. The LUG was on green, blue and red being LCPs. Neck boards were the classic ones with Motorola transistors. On the LUG I had taken out the resistor to ground on pin 6 and I ran a jumper wire from the G2 section to it (no need to drill out anything). On pin 7 I replaced the resistor to ground with a 10 meg ohm one (like in a G90).
I had very good focus on all tubes and the only reason I switched back to an all-LCP set was that the LUG would start blooming (=loosing focus) at contrast settings of 60 or above.
So my experience in short: Yes it works, but there are drawbacks.

BTW1: The incopatibility of the newer neck board is due to a redesign of the beam current limiting and the spot kill circuit. I think Scott (tse) discussed this somewhere else.

BTW2: If using LUGs, I only would use red and/or green ones. The smaller spot size on the blue will yield even less light than the blues already have. And under- or overfocussing will make their initial advantage useless.

Regards,
barclay66

mp20748 · Posted: Mon Sep 26, 2016 7:50 pm Post subject:

**Curt Palme** · Posted: Mon Sep 26, 2016 8:08 pm Post subject:

OK thanks for the input. BTW, when I had this problem years ago (maybe 5-6?) with a greeN LUG, I was positive that Terry sent me a bad tube. I then cut the LUG out of the Marquee housing, put it into a BArco, and it was fine, so it ended up not being the tube.

I just got word that Tim's blue tubes are at the border, so I'll grab them tomorrow and will put that set back on the bench. I will report as I go, as this has been annoying me, and I demand answers!

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

This may have some bearing on Greg's insistence that some neck cards are better than others when used with LUG tubes.

It's also why I've tried to get the COMPLETE Panasonic documents relating to the LCP and LUG tube types. So far without success.

I don't want excerpts, I want the WHOLE document.

There's something a bit mysterious about LUGs. Darned if I know what it is yet.

I wish I had a tube test rig that allowed me to dynamically vary all the voltages to all the elements of the electron gun and see how they interact and affect the picture. Gain a better understanding of the tube in the process.

I am of the opinion that the majority of the "classic" neck cards are anywhere between 10 and 20 years old now. The new VDC designed cards were available in 2006 for certain.

Due to the age of those classic cards, I am of the opinion that some issues we're seeing with them are component drifting and ageing issues. In particular I have to note that all forms of tantalum capacitors except for wet slug, acid bathed tantalums have a limited service life by time alone. There are not less than three surface mount (C size package) tantalum capacitors on each classic neck card and I recommend replacement of them. I HAVE seen SMT tants fail. Their failure mode is to short, more often than not.

The funniest bit of troubleshooting I ever did was to find a shorted SMT tantalum capacitor. There were DOZENS of them all over the power supply rails of the CRT monitor section of an HP analyzer I was working on. After spending hours and not finding the culprit, I finally said SCREW IT and applied my power supply to the problem. The problem was on a 15 volt line so I set my power supply to 15 volts at the voltage limiter, current limiter disabled, and ramped up the voltage on the rail in question. Just north of 12 volts, POW! Shorted cap FOUND, short CLEARED, scorch mark on the PC board marked the spot. A few minutes later with a fresh cap in place the sucker worked like a champ.

My fellow bench tech just looked at me funny for using that method. I said to him, "Wassa matter? Never seen a dynamic short clearing procedure before?"

greg9518lc · Joined: 19 Apr 2016 Posts: 360

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Guys

I have some 2039 neckboards here somewhere, VDC-modded for LUGs, I'll look for them and report back.

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

Just for informational purposes, I have now run-tested four different types of 9" tubes in the 9500LC I have designated as my current test bed.

P19LCP
P19LUG
P19LPB
P19LQF

Aside from the fact that only the LCP assigns G2 to pin 2, they all ran the same and they all focused with no issues,
and greyscale changes, if any, were more likely due to tube age and condition than on any differences between the tubes,
and although I did not try to evaluate their ultimate resolution and focus limits, all four tube types simply worked
fine with no apparent issues in my test chassis.

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

I spoke too soon. I've been working on refurbishing a number of projectors (off and on, not doing soimething every day) and neglected the work on my own personal Ultra hanging in my theatre. So iot was sitting there waiting for me to finish it up and
get it running again. It has new LUGs. All three, including blue.

So I got around to getting it running, began setup, and as soon as I got it through basic setup and convergence I ran some
movies on it as I continued to do adjustments. Initially I could see already that the LUGs are sharper. But I was chasing focus
issues in the green and red tubes. It wasn't getting to the razor sharp grid lines I was expecting to see, and getting out of the blue tube.

I finally decided that I just need to go back and do a baseline setup on the CRT assemblies with the CRTs installed on my test unit,
in my garage, so I can do everything in comfort and not have to reach up over my head.

I also installed freshly recalibrated focus yokes as part of the process. I had VDC recalibrate six sets of them for me. To the same specs they used on the later LUG-equipped simulation variant projectors. (Which, as it turns out, is the standard magnetic calibration for LCP tubes as well.) So I did a magnetic alignment on every aspect of the magnetics, including the 6 pole CPC rings, got nice clear round defocused halos, raster well centered, really set up like it should be. No problem.

I'm STILL having some issues where I can't get the corner focus as sharp as the center area. But only on red and green. Blue
is as perfectly sharp from corner to corner as I have ever seen. It's also a LUG tube, go figure. The only thing different about it is that it's made by Lexel. My green is a Mikado and the red is, I think, a VDC Clinton tube. I've never ever found any issues with
any lack of sharpness or performance out of those brands yet.

The focus issue I'm experiencing is a tendency to bloom in brigher scenes, and I only run my contrast at about 60 to 65 which isn't particularly bright. Blue seems to not be affected.

For a baseline test I'm going to take one of my three brand new complete VDC-made red LCP assemblies and drop that in for comparative purposes. It may not be exactly as sharp but I want to see how it blooms, or doesn't. I won't touch any of its
magnetic adjustments. I won't even take off any covers.

I do know that the new reds are VDC Clinton made tubes.

I have plenty of tubes to evaluate on my test bed. I think I'll run through quite a few over the weekend.

My sharp blue tube does tell me that LUGs can be run with awesome results in a Marquee. But the red and green tubes
are telling me that there may be some undesirable variances that have to be dealt with.

I have not encountered a tube that won't focus, but what I have encountered is tubes that don't retain focus well with
changes in picture brightness when using stock Marquee Thomson yokes, even ones that are calibrated.

More than ever I want to get my G90 yoke project completed. But you would not believe how difficult it has been for
me to find a transformer company who will even agree to wind up a few simple transformers for me to continue my
experiments with. I am no expert in winding transformers. I would rather pay someone to do it right.

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

Just for the fun of it lets try to increase the G2 voltage (that is actually turning down the G2 control in the menu) but increase the brightness to have the same level of black and see if it has any effect on this?

**Curt Palme** · Posted: Sat Dec 17, 2016 8:26 pm Post subject:

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

But oddly enough I just swapped out focus boards and now it's working a lot better.

I've never encountered a WEAK focus board before. I've seen them with outright failures, but this
is my first weak one.

The blooming and focus issues are greatly reduced with a new focus board in the PJ.

gregstv · Joined: 27 Aug 2007 Posts: 628 Location: Australia

What are the caps like on the weak focus board? It may be noise you are seeing.

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

Yeah, the caps are old, so is the board. I didn't have an extra FGM so I used an older regular focus board. I need to get a couple FGMs anyway.

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

The idea that LUGs bloom at higher contrast levels seems to be a characteristic noted only by Marquee users who are using LUGs
in their machines. LUGs in a G90 don't seem to suffer from this problem. I know, I have three running G90s and one has LUGs
in it, the other two have LQFs, and there's really no difference in their blooming characteristic.

Which, AGAIN, points to the inappropriateness and sub-par performance of the Thomson yokes with MEC tubs, when they
were designed for 40KV Thomson tubes which have substantially different focus requirements.

I SO wish that Electrohome had taken Panasonic's engineering advice and invested in proper focus yokes when they switched over to MEC tubes.

greg9518lc · Joined: 19 Apr 2016 Posts: 360

Mine don't bloom since I got new neckboards so go figure :D

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

But how are they regarding current drive and overall brightness?

Blooming is a function of beam profile purity and beam profile current density, Better focus yokes
help keep the beam tight over a broader beam current range.

There is NOTHING on the neck cards, ANY version, that has ANYTHING to do with how the magnetic focusing system works.

That is simple design fact.

The only thing about a neck card that can affect focusing is the beam current setting. If the neck card doesn't allow the beam to go to as high a current level as a different neck card, then yes, you could see a beam sharpness difference but it's also going to be a dimmer picture.

gjaky · Joined: 05 Jun 2010 Posts: 2802 Location: Budapest, Hungary

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

Isee what you're saying. Brightness and G2 are interactive. I've always followed a standard procedure of presetting contrast to 50
and brightness to 30 when setting G2, drive, and sub-brightness. (Or G2 and drive for older firmware) I may get better results
by running brightness and contrast at different base levels and compenate with different drive and G2 settings.

I'll certainly give it a shot.