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Discussion Starter · #1 ·
I've noticed that maxing out the brightness and contrast settings on my GE Imager 601 gives me a superior picture then with the settings lowered.


With the settings lowered I lose the subtle details in the picture especially in dark scenes where I lose noticable detail depending on how low I go.


I have read many posts talking about how bad it is to push a CRT projector like this? What effects will this have? Will I need to lower the settings?
 

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Something is definitely wrong if the picture looks acceptable with both contrast and brightness set to their maximum settings.


Brightness plays with the black level of the image: With it max'ed out, blacks should be almost a bright grey and no where near black. Either something's wrong with your projector's G2 setting or your source is the problem.


Having to run contrast at max means that one or more of the following is true (a) the projector's tubes light output level are very low (low emission) in which case you have no choice but to crank it up while it lasts, (b) your screen size is too large (how large is it? What's the gain?), (c) you're expected direct-view TV contrast levels from your projector and are pushing the tubes are to try to achieve this.


Kal
 

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Discussion Starter · #3 ·
When turning the brightness up blacks don't go bright grey but they do get a brownish color to them.


What is the G2 setting? Would an NEC PG6 have this setting?


My screen size is 80" 4:3 diag. Its on a white wall


I do expect direct-view TV contrast levels. Is this impossible with a projector?
 

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yes it is possible but you will need a 13 gain curved screen

and you will not have to run your contrast up all the way


XANATOS
 

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What you are missing is sub brigtness if your blacks are too black.


On a 6pg there are pots on one of the cards in the back to adjust this, it's under the metal shroud and fan in the back.


Better find out how to adjust it properly as the NEC's aren't a pj to just tweak things randomly on.


Anyway you probably need g2's adjusted properly also, that would explain why you are even able to drive contrast and brightness to max without ruining the picture so check g2 first. DONT TOUCH ANYTHING WITHOUT THE PROPER INFORMATION TO ADJUST IT RIGHT.


g2's are the three white knobs on the top begging you to adjust them.


I'm sure someone here has the info on how to set them properly...


Troy
 

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The only way to set up an NEC's reference mechanical white balance (which is what we're talking about in this thread) properly is to hire a REALLY good tech. Its harder than advanced Calculus done under the influence.

The only thing you have to worry about when you push your contrast and brightness is tubelife. If you don't care how long your tubes last, then push away. Many industrial installations do just that because they intend to replace the tubes every 3000 hours or so. Most HT users would rather light control the room, and have a slightly dimmer image so as to get MUCH more use out of the tubes, like in the 10,000 hour range. But if you don't care about long tube life, push away.

I have a Barco pamphlet detailing the improvements in one of their projectors and they state, as a selling point, that the improvements allow a user to run the projector at full contrast settings without any noticable blooming visible. They know some users NEED to push their pj's like that, but then again, they are selling most of their pj's to simulators and control rooms and other industrial applications which usually buy a service contract too.
 

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Discussion Starter · #7 ·
Quote:
The only way to set up an NEC's reference mechanical white balance (which is what we're talking about in this thread) properly is to hire a REALLY good tech.
I think setting the mechanical white balance could be the key because I've noticed that when using the "White Window" test pattern it is obviously not white but grey with the exception of the far left hand border which is white. I can get it closer to white (but still obviously grey) by setting the white level on the "White Balance" menu for the blue CRT to "81" and for the green CRT to "61". BTW after I changed this I had to lower the contrast or else I would sometimes see blue and green flares of color during the movie.


If anyone has any thread links on setting the NEC's reference mechanical white balance or about G2 setup please post them. No doubt it takes a great tech to properly adjust these settings but I might be able to at least improve on them.


Regardless of all this after ~10 hours of toying with my first CRT it already noticably beats the pants off my X1. Plus I have the new spacers on the way to help focus and Video Essentials and AVIA I bought off amazon.com which I think will be a help.


Thanks,

David
 

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Originally posted by TeKP
I think setting the mechanical white balance could be the key because I've noticed that when using the "White Window" test pattern it is obviously not white but grey with the exception of the far left hand border which is white.


David, what shape are the tubes in (looking onto tho phosophor surface with the tubes off)? I sounds like you may have some uneven wear on some of the tubes - especially since the outside of the image is white while the inside is greyer.

When turning the brightness up blacks don't go bright grey but they do get a brownish color to them.


This also leads me to beleive that the tubes are either unevenly worn or the G2 settings are off. If the image leans towards brown as you increase brightness then the red tube is driving harder then the other two - which is often the case with high-hour tubes as the red wears last.

My screen size is 80" 4:3 diag. Its on a white wall


So just regular paint? I think 'regular' flat paint is around 1.0 gain. Your best bet for CRT is at least 1.3 gain. The purists will say stick to 1.3 to limit hotspotting/colourshifting while others will go higher to get a brighter image.

I do expect direct-view TV contrast levels. Is this impossible with a projector?


Not impossible if the gain's high enough and you keep the screen small enough (80" is definitely not large so that's ok). Most direct view's do around 30 foot-lamberts because they're used with the lights on. A front projection system in a light controlled room will look plenty bright at around 12-15 foot-lamberts. You don't need more then this really.


Are you wanting to watch with the lights on? If that's the case, a digital projector's probably the best idea.


Kal
 

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Quote"No doubt it takes a great tech to properly adjust these settings but I might be able to at least improve on them."

Actually, no you won't.

No offence intended, at all.

I wouldn't trust even a trained tech to attempt that adjustment, UNLESS they were an experienced AND SPECIFICALLY NEC trained tech.

The MECHANICAL reference white balance of an NEC MUST be setup via signal generator, scope and years of training. IF you try it yourself by "twiddling" pots you WILL ruin it. What I'm referring to, was NEVER intended to be in need of any "adjustment" after the CRT left the factory, but may have been affected by any number of unforseen factors.

However, you may be able to set the G2 a little better; BUT this could interact negatively with your reference mechanical white balance.

G2 is specifically, the point at which the tubes turn on. This is the basis for just about everything else, as the tube must turn on to show ANY image.

What you need to do is exactly what you did. Use the "White Balance" settings, they are intended for the user to change as they are not permanent(you can "Save" them and they will be in effect every time you use that input, but you can as easily "Normalize" them or just set them back to null and "Save" that) nor do they affect the reference mechanical white balance.

By getting your "White Balance" closer to D6500, you will be rewarded with better shadow detail and still bright white detail. You should be able to reduce your brightness setting and likely your contrast too and still have as good an image as you have now, with those settings turned all the way up.

It sounds as if maybe some previous user fiddled with the G2 and turned them down, OR perhaps set the mechanical reference white balance with the brightness and contrast controls too low.

Did you do the obvious first, go into "White Balance" and hit "Normal" button, and answer "Yes" to the query about returning the setting to normal ?

Also, did you try turning AKB on, then back off ?

Try these first before you go on to anything else.

.
 

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Discussion Starter · #10 ·
Alright, note to self... do not mess with mechanical reference white balance :)


Sounds like it's better if I just forget I ever heard about it.


Yes I have normalized all the settings. I just deleted all the existing signal entries and started with a new one. If anything I guess I'll try to find some information on the G2 and try your AKB suggestion.


Thanks,

David
 

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DO use the menu item called "White Balance", it is designed to do exactly what you want to do. The "White Balance" menu is NOT the reference mechanical white balance, sorry if I wasn't clear about that.

Kal is likely correct about your tube condition, you should pull the lenses off to confirm the condition of the tubes. If they are worn, then blast away with the bright/contrast controls till you replace the tubes.
 

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Discussion Starter · #12 ·
I have used the White Balance Controls. It did in fact help the picture.


I have taken the lenses off and I am not an expert but the tube condition looks excellent. I don't see any visible wear or burn at all on any of the tubes.


I don't think the bright white border on the "White Window" test is a result of the tube wear because it is a very thin line of bright white on the far left hand side of the white window. I think it is a setting of some sort. I do not see this brightness variation on a plain white background from a different source such as my HTPC.
 

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TeKP, your GE and mine came from the same origination (not just the reseller, but from whom they were owned by). Mine will be installed and calibrated within the next week or so I'll report back on the final results.


I did get a chance to see the unit I bought at the reseller's home and it looked great. My unit had more hours than your unit did, but no visible wear on any of the tubes for the unit I got. Your unit had less hours, IIRC.


Do yourself a BIG favor and have someone to professionally calibrate the unit.
 

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Discussion Starter · #14 ·
It probably is a good idea to have someone professionally calibrate it.


Does anyone know a good NEC technician in South Florida?
 

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Ok so you have perfect tubes, you'll likely want to stop maxing out contrast and brightness.

There is one unfortuneate dimension to NEC projectors, and that is the reference mechanical white balance. If anyone messes with it, you're up the creek, so to speak. Until you can get a pro to fix it, use the "White Balance" adjustments to get the white balance back to a more normal position.

Do you have the service manual ? If not, you can download a good pdf copy for a reasonable amount from www.freebrd.com . I'm pretty sure it will outline the procedure for reference mechanical white balance setup in case you wanted to take a look at it. Do you have a background in electronics ? Maybe you could become an expert ?
 
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